Pediatric Pathology
ISSN: 0277-0938 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/ipdp17
Hepatoblastoma: The Prognostic Significance of Histologic Type Richard M. Conran, Charles L. Hitchcock, Myron A. Waclawiw, J. Thomas Stocker & Kamal G. Ishak To cite this article: Richard M. Conran, Charles L. Hitchcock, Myron A. Waclawiw, J. Thomas Stocker & Kamal G. Ishak (1992) Hepatoblastoma: The Prognostic Significance of Histologic Type, Pediatric Pathology, 12:2, 167-183 To link to this article: http://dx.doi.org/10.3109/15513819209023293
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Date: 31 October 2015, At: 07:09
HEPATOBLASTOMA: The Prognostic Significance of Histologic Type
Richard M. Conran, Maj, MC, USA
0 Department of Pediatric Pathology, Armed Forces Institute of Pathology, Washington, D . C . 20306-6000
Charles L. Hitchcock, Maj, MC, USAF 0 Department of Cellular Pathology, Armed Forces Institute of Pathology, Washington, D . C . 20306-6000 Myron A. Waclawiw, PhD
0
NHLBI, Biostatistic Research Branch,
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Bethesda, Maryland 20892
J. Thomas Stocker, COI, MC, USA
0
Armed Forces Institute of
Pathology, Washington, D . C . 20306-6000
Kamal G. Ishak, MD, PhD 0 Department of Hepatic and Gastrointestinal Pathology, Armed Forces Institute of Pathology, Washington, D.C. 20306-6000
0 The clinicopathologicfeatures of 105 hepatoblastomas accessioned to the Armed Forces Institute of Pathology between 1967 and 1987 were reviewed. D N A content was analyzed by flow cytometty. A multivariate analysis using the Cox proportional hazards model was perfoned to evaluate the effect of stage, histologic type, and D N A content on the prognosis for survival. The relative risks of death for a given stage compared to the other stages combined were 0.1637, 0.5672, 2.8742, and 3.5148 for stages I - I v respectively. The relative risk of death for a given histologic ype adjusted for age, sex, and stage compared to the other types was I . 0739 (p ,8850)for the fetal pattern, I . 7409 (p = ,1662) for the embryonal pattern, 0.5292 (p ,0754) for the mixed pattern, 1.1980 (p ,7729) for the macrotrabecular pattern, and 3.7096 (p ,1061) for the small-cell undigerentiated pattern. Of 19 hepatoblastomas analyzed for D N A content, 5 were D N A diploid and I 1 were D N A aneuploid; 3 could not be class$ed. The stage of disease at presentation proved to be a significant prognostic factor, whereas histologic type and D N A content did not have a significant effect.
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KEY WORDS: hepatoblastoma, liuer tumor, flow cytometry.
The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Departments of the Army, Air Force, or Defense. Presented in part at the Society for Pediatric Pathology Annual Meeting, March 3-4, 1990, Boston. Conran RM, Stocker JT, Ishak KG. Hepatoblastoma: 1967-1987. (Abstract) Mod Pathol 1990;3:2P. Address reprint requests to: Editorial Office, Armed Forces Institute of Pathology, Washington, DC 20306-6000.
Pediatric Pathology, 12:167-183, 1992 Copyright @ 1992 by Hemisphere Publishing Corporation
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Hepatoblastoma (HB) is a unique neoplasm of childhood with an annual incidence of 1 per million children. A review (1) of 35 HBs accessioned to the Armed Forces Institute of Pathology (AFIP) between 1927 and 1967 identified two basic histologic types: an epithelial type, with a fetal or embryonal pattern or combination of both, and a mixed type, which contained primitive mesenchymal cells in addition to the epithelial component. Following this report, Kasai and Watanabe (2) described a third distinctive pattern, the anaplastic pattern, more recently referred to as the small-cell undifferentiated pattern (3). A fourth distinct pattern, macrotrabecular, was subsequently described by Gonzalez-Crussi et al. (4). A variant of the mixed type of hepatoblastoma, first reported by Misugi and Reiner (5), contains elements from all three germ layers and has been named teratoid HB by Manivel et al. (6). Many reviews have attempted to correlate histologic type with prognosis (1, 2, 4, 7-12), a number suggesting that the pure fetal pattern had a better prognosis (2, 7, 9, 12). Weinberg and Finegold (9) in a review of 27 HBs reported that the prognostic effect of histologic type was based on the epithelial and not the mesenchymal component and that the pure fetal pattern had a better prognosis that the other types. Schmidt et al. (10) studied 24 HBs and observed no difference between the fetal and embryonal patterns. A limitation of these studies was that they did not adjust for clinical stage. Haas et al. (12) reviewed 168 HBs classified on the basis of their epithelial component alone and found an excellent prognosis for stage I (complete resection) HB that had a pure fetal pattern. No prognostic effect for histologic type was observed for stage 11-IV (incomplete resection) HBs; however, the presence of osteoid was a positive prognostic feature for this group. Because of our interest in this neoplasm, the controversy outlined above, and our bias of classifying HB on the basis of both the epithelial and mesenchymal components, we reviewed the clinicopathologic features of 105 HBs accessioned to the AFIP between 1967 and 1987. The prognostic significance of stage, histologic type, and DNA content for survival was evaluated.
METHODS The clinical summaries, surgical pathology and autopsy reports and submitted slides for 105 HBs were reviewed. Follow-up information was obtained from the submitting institutions. Ninety-two cases were submitted as surgical specimens and 13 as autopsy specimens. The number of slides submitted per case ranged from 1 to 24. The mean slide to maximum tumor diameter ratio was 0.71 with a standard deviation of 0.69 for all cases reviewed and a mean of 0.72 with a standard deviation of 0.61 for completely resected (stage I) HBs. The maximum tumor
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diameter was recorded for 36 of 45 completely resected and 35 of 60 partially resected or unresected HBs. Hepatoblastomas were initially classified on their epithelial and mesenchymal components into one of six histologic types (Table 1). The same tumors were alternatively classified on their epithelial component alone into one of four histologic types in order to assess the significance of histologic type for prognosis. Ten HBs could not be classified due to limited material or chemotherapy-induced changes and are designated as HB NOS (hepatoblastoma-not otherwise specified). When HBs were classified on their epithelial component alone, 11 were designated HB NOS. For the purpose of this study, the fetal pattern refers to an HB where 100% of the tumor is composed of small, round, uniform cells with abundant cytoplasm and distinct cytoplasmic membranes. The cells are arranged in thin trabeculae, usually two to three cells thick, with alternating light and dark areas (Fig. 1). The embryonal pattern refers to an HB where any part of the tumor has cells arranged in sheets of irregular, angulated cells with a high nucleocytoplasmic ratio, increased nuclear chromatin, and indistinct cytoplasmic membranes, Pseudorosette and acinar formation are common features (Fig. 2). Foci of extramedullary hematopoiesis are seen in both the fetal and embryonal areas. The macrotrabecular pattern refers to an HB in which trabeculae more than 10 cells thick are present as a repetitive pattern. The large trabeculae contain either fetal or embryonal type cells, or a third larger cell type with cytoplasm that is more abundant than in normal hepatocytes or fetal type cells, or a combination of all three cell types (Fig. 3). An HB with embryonal or mesenchymal cells and only an isolated rnacrotrabecular focus was classified on the embryonal or mesenchymal cell component present and not as macrotrabecular. The small cell pattern consists of a diffuse population of small cells with TABLE 1. Histologic Classification of Hepatoblastoma Based on Epithelial and Mesenchymal Components
I.
Epithelial type A. Fetal pattern B. Embryonal pattern C . Macrotrabecular pattern D. Small cell undifferentiated pattern 11. Mixed epithelial and mesenchymal type A. Mixed pattern without teratoid features B. Mixed pattern with teratoid features 111. HB NOS (not otherwise specified)
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FIGURE 1. Hepatoblastoma: fetal pattern. (a) Low-magnification photograph showing alternating light and dark areas. X 75. (b) Uniform population of cells with abundant vacuolated (light area) or granular (dark area) cytoplasm, distinct cytoplasmic membranes, and small round nuclei characterizes the fetal pattern. Extramedullary hematopoiesis (arrow) is present. X 300.
scant cytoplasm and indistinct cytoplasmic membranes, resembling neuroblastoma cells (Fig. 4). Areas of other recognizable HB patterns must be present before a diagnosis of the small cell variant is made. The mixed pattern has a combination of fetal or embryonal patterns intermixed with primitive spindled mesenchymal cells. Osteoid-like material is a common component in the majority of mixed HBs (Fig. 5). The mixed pattern with teratoid features contains the above epithelial and mesenchymal elements, as well as various combination of foci of mature cartilage, skeletal muscle, intestinal-type and keratinized squamous epithelium, and melanin pigment (Fig. 6 ) . For survival analysis, 11 cases that consisted of 4 intraoperative deaths, 3 perioperative deaths secondary to hemorrhage and infection, 3 deaths secondary to liver rupture at presentation, and 1 neonatal death were excluded. The remaining 94 cases were staged as outlined in Table 2 (12). Four cases that were lost to follow-up within 2 years of diagnosis were excluded in the computation of .the 2-year disease-free survival rates for histologic type, stratified by stage.
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The Cox Proportional Hazards model (13) was used to evaluate stage = 94), histologic type (N = 84), and DNA content (N = 19) for their prognostic effect on survival. Hepatoblastomas designated as HB NOS were not included in the study of the relative risk of death for histologic type. Because of limited numbers of incompletely resected HBs, stages 11-IV were combined for the analysis of the relative risk of death for histologic type, stratified by stage. A P value < .05 was considered statistically significant. In order to obviate sampling error in the cases represented by a single slide, the relative risk of death for histologic type was done initially on all cases (N 84) and then repeated on all cases with more than one slide (N 66). Both analyses yielded consistent estimates and conclusions. Henceforth, results based on N = 84 are presented. Initial review of the relative risk of death showed no significant difference (RR = .4419, P = .1667) between the mixed type without teratoid features and the mixed type with teratoid features; they were therefore combined and listed as mixed type and are also listed separately in Tables 6 and 7 . Nineteen HBs were submitted for flow cytometry. Technical aspects have been reported (14). T h e DNA content of the isolated nuclei obtained from areas of tumor and nonneoplastic liver was measured on an EPICS 541 flow cytometer (Coulter Cytometry, Hialeah, Florida) equipped with a 5-W argon laser used at an excitation wavelength of 488 nm. At least 2 X lo4 nuclei
(N
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FIGURE 2. Hepatoblastoma: embryonal pattern. Angulated cells with hyperchromatic nuclei, minimal cytoplasm, and indistinct cytoplasmic membranes form irregular rosettes. X 300.
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FIGURE 3. Hepatoblastoma: macrotrabecularpattern. (a) Large trabeculae more than 10 cells thick (top) are present adjacent to fetal area (bottom). X 75. (b) The cells making up the rnacrotrabeculae are more variable in size than the cells in the fetal pattern (compare with Fig. 1). X300.
per sample were collected at a flow rate of no more than 100 events per second for each DNA histogram. The effects of debris and doublets were minimized by gating on the peak and integrated red signals. Light scatter and red fluorescence signals were collected in list mode. All DNA histograms were analyzed by one of us (C.L.H.) without knowledge of the histologic type, stage, or patients' clinical course. Tumors were classified as DNA diploid (single GO/G1 peak) or DNA aneuploid (distinct second GO/G1 peak). In several cases, definition of the DNA aneuploid cell population required separation of subpopulations of nuclei based on their forward angle light scatter (FALS) and right angle (90') light scatter signals. List mode data were played back and single-parameter DNA histograms were derived from gating on different populations based on their light scatter properties. DNA analysis was calculated using the CytoLogic computer program (version 2.1, Coulter Cytometrics).
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RESULTS Clinical Features The age at diagnosis, sex, anL race of the 105 HB cases reviewed were similar to those previously reported (1). Clinical features and laboratory data were also similar. Most HBs (95%) were not associated with underlying liver disease, and only one HB was associated with a concurrent second malignancy (adrenal carcinoma) at diagnosis.
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Gross Features The gross features of the HBs reviewed were also similar to those previously reported (1). There was no difference in the maximum tumor diameter between completely resected HBs (mean 9 . 8 7 cm, SD 2 . 5 7 ) and partially or nonresected HBs (mean 9 . 3 0 cm, SD 2 . 7 3 ) .
Histologic Features The 105 HBs, when classified on the basis of both their epithelial and mesenchymal components, were distributed into the following histologic types: fetal 2 8 % , embryonal 1 7 % , mixed without teratoid features 3 1 % ,
FIGURE 4. Hepatoblastoma: small cell pattern. This diffuse population of small cells has hyperchromatic nuclei, a high nucleocytoplasmic ratio, and indistinct cytoplasmic membranes.
X
300.
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FIGURE 5. Hepatoblastoma: mixed pattern. (a) Epithelial elements are intermixed with primitive mesenchymal cells (M) and osteoid-like material (arrows). X 75. (b) Spindle-shaped mesenchymal cells separate foci of osteoid-like material. X 300.
mixed with teratoid features 9%, macrotrabecular 3 7% , small cell 3 % , and HB NOS 9 % . The percentage of fetal and embryonal HBs in the current study was similar to that previously reported (1). With the addition of the macrotrabecular and small cell patterns since 1967, the percentage of mixed HBs (which includes those with teratoid features) decreased from 54 to 40%. When the same tumors were classified on the basis of their epithelial component alone, the following distribution was obtained: fetal 2976, embryonal 55 76,macrotrabecular 3 % , small cell 3 % , and HB NOS 10 % . The percentage of fetal, small cell, and macrotrabecular HBs remained constant between the two classifications, whereas the percentage of embryonal HBs increased when the epithelial component alone was considered. Fetal HBs for the most part showed features similar to those previously reported; however, in a number of cases the fetal cells appeared to be similar in size to the surrounding nonneoplastic hepatocytes rather than being smaller. Mitotic figures for the most part were scarce; however, there were isolated tumors with a mitotic rate
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FIGURE 6. Hepatoblastoma: mixed pattern with teratoid features. (a) Keratinized squamous epithelium (arrow) adjacent to osteoid-like material ( X 75), (b) intestinal-type epithelium ( X 150), (c) striated muscle cells ( X 300), and (d) melanin pigment ( X 300) are some of the teratoid elements seen in this pattern.
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TABLE 2. Staging Classification Stage I Stage I1
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Stage 111 Stage IV
Complete resection Microscopic residual, negative nodal involvement, no spilled tumor Gross residual or nodal involvement or spilled tumor Metastatic disease
of up to 24 mitoses per 1.96 mm2 (10 high-power fields). Extramedullary hematopoiesis varied among tumors. In most fetal HBs, trabeculae were two or three cells thick, although trabeculae four to eight cells thick could be seen occasionally, but a repetitive pattern was not identified. All embryonal HBs in our study contained both fetal and embryonal areas. No pure embryonal HB was identified. The three HBs that were classified as macrotrabecular contained both fetal and embryonal cells in the trabeculae. One of the three contained very large cells similar to those seen in hepatocellular carcinoma. All but one mixed HB contained both fetal and embryonal patterns as the epithelial component. The one exception contained only fetal cells in association with the mesenchymal elements; however, only two slides were available for review from that tumor. The nonneoplastic liver was normal in 91 % (63 of 69) of the cases when present on the slides reviewed. Portal fibrosis, fatty change, and cirrhosis were the pathologic processes present in the six cases with abnormal livers.
Flow Cytometry One to two blocks per case from 19 HBs were submitted for DNA analysis by flow cytometry. Of the 19 cases, 3 yielded uninterpretable histograms, 5 were DNA diploid, and 11 had a DNA aneuploid stemline present. No correlation was observed between DNA ploidy and stage or histologic type (Table 3). Prognosis Of the 94 HBs for which survival data were available, the cases were distributed into the following stages: stage I 48%, stage I1 7%, stage I11 27%, and stage IV 18%. Eighty-two percent (56 of 68) of patients reported receiving adjuvant chemotherapy; however, only 56% (19 of 34) of stage I patients reported its use. Eight of the 68 patients had also received chemotherapy, preoperatively, to reduce the size of the tumor prior to excision. Thirty-five percent (24 of 68) of patients also reported use of radiotherapy in conjunction with chemotherapy. Four of the patients were lost to follow-up during the first 2 years after
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TABLE 3. Flow Cytometric Analysis of HBs: Distribution by Stage and Histologic Type
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Stage" Histologic type
I
Fetal Embryonal Mixed Mixed teratoid Macrotrabecular Small cell
3A,2D 2A 2D 1A 1A
I1
I11
IV
1A 1D 1A
1A 1A
'A, DNA aneuploid; D, DNA diploid.
diagnosis. Forty-seven of the remaining 90 patients were alive 2 years after diagnosis; 45 were disease free and 2 were alive with disease. The 2-year disease-free survival was better for stage I tumors (81%) than for the other stages (stage I1 66%, stage 111 21%, stage IV 18%). Survival by histologic type (Table 4) was good for stage I fetal and mixed HBs and stage 11-IV mixed HBs. The 2-year disease-free survival by histologic type for HBs classified on their epithelial component alone showed the following distributions: stage I (fetal 94%, embryonal 67 %, macrotrabecular 0%) and stages 11-IV (fetal 11 % , embryonal 32 % , macrotrabecular 0 % , and small cell undifferentiated 0%). The relative risk of death for stage (Table 5) indicates a good prognosis for stage I HBs and a poor prognosis for stage I11 and IV HBs relative to the other stages combined. No significant effect was observed in the relative risk of death for histologic type when adjusted for age, sex, and stage (Tables 6 and TABLE 4. Percent Survival' for Given Histologic Typeb Stratified by Stage
Histologic type
All stages
Fetal Embryonal Mixedd Mixed teratoid Macrotrabecular Small cell undifferentiated HB NOS
64 (25)' 31 (13) 61 (28) 44 (9) 0 (3) 0 (2) 50 (10)
Complete resection (stage I)
Incomplete resection (stages 11-IV)
93 (16) 57 (7) 91 (11) 50 ( 6 ) 0 (1)
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100 (2)
"Alive without disease for a minimum of 2 years; excludes intraoperative/perioperativedeaths (1 1) and four cases lost to followup during first 2 years after diagnosis. 'Cases classified on their epithelial and mesenchymal components. 'Number in parentheses represents the number of cases in that stage. dRepresents mixed HB without teratoid features.
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TABLE 5. Relative Risk of Death for Given Stage",' Stage
Relative risk
P value
I I1 111 IV
0.1637 0.5672 2.8742 3.5148
< .00001 ,4375 ,0013 ,0002
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'Stage of interest compared to other stages combined. 'Cases adjusted for age and sex.
8), but when cases were adjusted for age and sex, but stratified by stage (Tables 7 and 9), the macrotrabecular and small cell types were associated with a poorer prognosis. The fetal type did not demonstrate a positive prognostic effect, regardless of whether the tumors were classified on their epithelial component alone or on the combination of their epithelial and mesenchymal components. For the mixed HBs (Table 6), the relative risk of death for the mixed HBs without teratoid features compared to all other types was .4685 (P = .0542), demonstrating a borderline significant positive prognostic effect. When the cases were stratified by stage (Table 7), the positive prognostic effect was not seen for completely resected HBs but was present for incompletely resected lesions. The relative risk of death for DNA diploid versus DNA aneuploid tumors adjusted for age, sex, and stage was .0012 but was not significant (P = .7909). DNA content was not a factor in terms of survival.
DISCUSSION
A number of studies have appeared in the literature after our initial report of 35 HBs from this institution (1). Most of them, however, have been case TABLE 6. Relative Risk of Death for Given Histologic Type" for Cases Classified on Both Epithelial and Mesenchymal Components' Histologic type
Relative risk
Fetal Embryonal Mixed' Without teratoid features With teratoid features Macrotrabecular Small cell
1.0739 1.7409 0.5292 0.4685 1.1274 1.1980 3.7096
P value ,8850 ,1662
,0754 .0542 .8128 .7729 .lo61
"Histologic type of interest compared to other histologic types. 'Cases adjusted for age, sex, and stage. 'Includes all mixed HBs with and without teratoid features.
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TABLE 7. Relative Risk of Death for Given Histologic Type" for Cases Classified on Their Epithelial and Mesenchymal Components and Stratified by Stageb
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Complete resection (stage I)
Incomplete resection (stages 11-IV)
Histologic type
Relative risk
P value
Relative risk
P value
Fetal Embryonal Mixed' Without teratoid features With teratoid features Macrotrabecular Small cell
0.0000002 2.8376 1.4532 0.2970 5.1847 38.8375
,5292 ,1670 .6177 ,2645 ,0263 ,0292
1.6645 1.5956 0.3862 0.4011 0.7503 1.2869 5.4366
.3216 ,3334 ,0242 ,0429 ,7037 ,7320 ,0346
"Histologic type of interest compared to other histologic types. *Cases adjusted for age and sex, stratified by stage. 'Includes all mixed HBs with and without teratoid features.
reports or small series of less than 30 cases, precluding accurate survival analysis. Submission of cases to study groups (Pediatric Oncology Group, POG; Childrens Cancer Study Group, CCSG; Armed Forces Institute of Pathology, AFIP) has resulted in larger numbers of cases being available for review. These studies, however, are limited by the gross description and number of slides submitted for review. In order to investigate the prognostic significance of histologic type, we reviewed 105 HBs submitted to the AFIP over the last 20 years. Stage at presentation, histologic type, and relative DNA content were analyzed for their effect on prognosis. Stage at presentation was the most important factor. The relative risk of death for stage I HBs compared to the other stages combined demonstrated a good prognosis. The lack of significance for stage I1 HBs (P = .4375) is probably related to the small number of cases). The effect of adjuvant chemotherapy on survival was not addressed in this study because of the variation in treatment protocols employed over the 20TABLE 8. Relative Risk of Death for Given Histologic Type' for Cases Classified on Their Epithelial Component Only* Histologic type
Relative risk
P value
Fetal Embryonal Macrotrabecular Small cell
1.0188 0.7446 1.2223 3.6878
,9702 ,4468 ,7488 ,1085
"Histologic type of interest compared to other histologic types. *Cases adjusted for age, sex, and stage.
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TABLE 9. Relative Risk of Death for Given Histologic Type' Classified on Epithelial Component Alone and Stratified by Stageb
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Complete resection (stage I)
Incomplete resection (stages 11-IV)
Histologic type
Relative risk
P value
Relative risk
P value
Fetal Embryonal Macrotrabecular Small cell
0.0000001 7.9260 38.8375
,5010 .0986 ,0292
1.7058 0.4313 1.3004 5.3602
,3045 ,0642 .7218 ,0367
-
-
"Histologic type of interest compared to other histologic types. k a s e s adjusted for age and sex, stratified by stage.
year period when the cases were collected. Twenty percent (8 of 40) of longterm survivors in this study, however, did not receive any chemotherapy. Utilizing a P value of less than .05 as a level of significance, we did not identify one histologic type as being superior to any other in terms of survival. The pure fetal pattern stage I and the mixed pattern both demonstrated good survival when the 2-year disease-free interval stratified by stage was considered. However, when a multivariate analysis is performed adjusting for variables such as stage and cases lost to follow-up, no significant difference in survival for histologic type was observed, regardless of whether the tumors were classified on their epithelial component alone or on their mesenchymal and epithelial components combined. The mixed histologic pattern (cases with and without teratoid features) had a borderline significantly positive prognostic effect on survival. We addressed the question of whether we should separate the mixed HBs without teratoid features from the mixed HBs with teratoid features. The percentage of cases with 2-year survival differs between the two groups, suggesting a better prognosis for the mixed HBs without teratoid features. We found, however, no significant difference in the relative risk of death between these two groups. We feel that analysis of a larger number of mixed HBs with teratoid features is needed to determine whether they behave differently from the mixed type without teratoid features and whether they should be considered as two separate groups. None of the mixed HBs with teratoid features were associated with preoperative chemotherapy in this study. When the mixed HBs as a group were stratified, but not adjusted for stage, the mixed HBs for incompletely resected lesions had a good prognosis. This is consistent with the CCSG observation (12) of the positive prognostic effect of osteoid for incompletely resected HBs. The macrotrabecular and small cell patterns appear to have a poor prognosis; the number of small cell and macrotrabecular HBs in our study is too small to draw a meaningful conclusion, but this is consistent with the reports of others.
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O u r observations are similar to those of Schmidt et al. (lo), who noted no difference between the fetal and embryonal patterns. Also, we agree with the original impression of Ishak and Glunz (1) and that of Dehner (8) about the good effect of the mixed pattern. In contrast to the view of Weinberg and Finegold (9), we favor continuing to classify HBs on both their epithelial and mesenchymal components because of the prognostic significance of the osteoid-like material and mesenchymal elements. O u r data do not support the view of Haas et al. (1 2) that the pure fetal pattern for completely resected HBs by itself has a positive prognostic value. Although the HBs in their study were classified on the epithelial component alone and a P value < .1 was considered significant, we did not find a positive prognostic value for our cases when classified on the epithelial component alone at a significance level of < .1. This discrepancy may be due in part to inaccurate classification. Adequate sampling, as recommended by Gonzalez-Crussi et al. (4), was a weakness of both studies. This presents a problem in classifying the fetal pattern as pure fetal. In order to diminish inadequate sampling as a reason for the discrepancy, we performed the same analysis excluding all cases for which only one slide was available for review. Similar results were obtained. Also, as in the study of Lack et al. (7), we found that we could not classify 10% of our HBs because of the type of specimen (needle biopsy) or chemotherapy effect. The CCSG (12) did not report this as a problem in their study. Variations in interpretation of histologic criteria could be another problem. We interpret a number of observations in the literature about the positive prognostic effect of the fetal pattern to be related to stage and not histology. The prognostic significance of DNA ploidy, oncogenes, and tumor cytogenetics is an area of recent interest. DNA content has been shown to be of prognostic value in a number of malignancies (15); however, its prognostic role in pediatric solid tumors is still being defined. Two exceptions are neuroblastoma and Wilms’ tumor (16-18). Flow cytometric analyses of pediatric liver tumors are limited. The only HB flow cytometric analysis that we are aware of is the report by Orozco-Florian et al. (19) on a DNA aneuploid congenital HB in a patient with Beckwith-Wiedemann syndrome who died at 2 weeks of age. Leuschner et al. (20) reported that four of five cases of undifferentiated sarcoma of the liver were DNA diploid and the other DNA aneuploid; the DNA aneuploid tumor had a poorer prognosis. We submitted approximately 20% of our cases for flow cytometry and found that DNA content was not a significant prognostic factor. Further study using larger numbers of cases is needed, but our preliminary data indicate that DNA content is not a prognostic factor and does not correlate with histologic type. Amplification of c-myc and. N-myc oncogenes, associated with a poor prognosis in neuroblastoma, was not observed in 10 HBs examined by Tsuda et al. (21). Tumor cytogenetic analysis has been reported in four HBs with a mixed pattern (22).
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Abnormalities of chromosomes 2 and 20 were identified. The prognostic significance of the observed karyotypes was not addressed. In summary, stage at presentation and the ability to resect the tumor completely appear to be the most important prognostic factors at this time. Hepatoblastoma is a tumor with a spectrum of histologic patterns. We favor continuing to classify the tumor on the basis of both the epithelial and mesenchymal components. We did not document that one histologic type was superior to the others, although the mixed HB appears to have the best overall survival. DNA content was not a prognostic factor.
REFERENCES 1 . Ishak KG, Glunz PR. Hepatoblastoma and hepatocarcinoma in infancy and childhood. Report of 47 cases. Cancer 1967;20:396-422. 2. Kasai M , Watanabe I. Histologic classification of liver-cell carcinoma in infancy and childhood and its clinical evaluation. A study of 70 cases collected in Japan. Cancer 1970;25:551-63. 3. Haas J, Musczynski K, Kraillo M et al. Relationship of cytohistopathology to outcome in malignant epithelial hepatic tumors of childhood. (Abstract) Lab Invest 1988;58:4P. 4. Gonzalez-Crussi F, Upton MP, Maurer HS. Hepatoblastoma. Attempt at characterization of histologic subtypes. Am J Surg Pathol 1982;6:599-612. 5 . Misugi K, Reiner CB. A malignant true teratoma of liver in childhood. Arch Pathol 1965;80:409-12. 6. Manivel C, Wick MR, Abenoza P, Dehner LP. Teratoid hepatoblastoma. The nosologic dilemma of solid embryonic neoplasms of childhood. Cancer 1986;57:2168-74. 7. Lack EE, Neave C , Vawter GF. Hepatoblastoma. A clinical and pathologic study of 54 cases. Am J Surg Pathol 1982;6:693-705. 8. Dehner LP. Hepatic tumors in the pediatric age group: A distinctive clinicopathologic spectrum. Perspect Pediatr Pathol 1978;4:217-68. 9. Weinberg AG, Finegold MJ. Primary hepatic tumors of childhood, Hum Pathol 1983;14:512-37. 10. Schmidt D, Harms D, Lang W. Primary malignant hepatic tumors in childhood. Virchows Arch (A) 1985;407:387-405. 1 1 . Dehner LP, Manivel JC: Hepatoblastoma: An analysis of the relationship between morphologic subtypes and prognosis. Am J Pediatr Hematol Oncol 1988;10:301-7. 12. Haas JE, Muczynski KA, Krailo M, et al. Histopathology and prognosis in childhood hepatoblastoma and hepatocarcinoma. Cancer 1989;64:1082-95. 13. SAS Institute. SUGI Supplemental Users Guide. Version 5 edition. North Carolina: SAS Institute, 1986. 14. Hitchcock CL, Norris HJ, Khalifa MA, Wargotz ES. Flow cytometric analysis of granulosa tumors. Cancer 1989;64:2 127-32. 15. Koss LG, Czerniak B, Herz F, Wersto RP. Flow cytometric measurements of DNA and other cell components in human tumors: A critical appraisal. Hum Pathol 1989;20:528-48. 16. Cohn SL, Rademaker AW, Salwen HR, et al. Analysis of DNA ploidy and proliferative activity in relation to histology and N-myc amplification in neuroblastoma. Am J Pathol 1990; 136:1043-52. 17. Look AT, Hayes FA, Nitschke R, McWilliams NB, Green AA. Cellular DNA content as a predictor of response to chemotherapy in infants with unresectable neuroblastoma. N Engl J Med 1984;311:231-5. 18. Douglass EC, Look AT, Webber B, et al. Hyperdiploidy and chromosomal rearrangements define the anaplastic variant of Wilms’ tumor. J Clin Oncol 1986;4:975-81. 19. Orozco-Florian R,McBride JA, Favara BE, Steele A, Brown SJ, Steele P. Congenital hepatoblastoma and Beckwith-Wiedemann syndrome: A case study including DNA ploidy profiles of tumor and adrenal cytomegaly. Pediatr Pathol 1991;11:131-42. 20. Leuschner I , Schmidt D, Harms D. Undifferentiated sarcoma of the liver in childhood: Morphology, flow cytometry, and literature review. Hum Pathol 1990;21:68-76.
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21. Tsuda H , Shimosato Y, Upton MP, et al. Retrospective study on amplification of N-myc and c-myc
genes in pediatric solid tumors and its association with prognosis and tumor differentiation. Lab Invest 1988;59:321-7. 22. Fletcher JA, Kozakewich HP, Pavelka K, et al. Consistent cytogenetic aberrations in hepatoblastoma: A common pathway of genetic alterations in embryonal liver and skeletal muscle malignancies? Genes Chromosomes Cancer 1991 ;3:37-43.
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ReceivedJune 17, 1991 Revition Accepted Aufust 22, 1991
ISSN: 0277-0938 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/ipdp17
Hepatoblastoma: The Prognostic Significance of Histologic Type Richard M. Conran, Charles L. Hitchcock, Myron A. Waclawiw, J. Thomas Stocker & Kamal G. Ishak To cite this article: Richard M. Conran, Charles L. Hitchcock, Myron A. Waclawiw, J. Thomas Stocker & Kamal G. Ishak (1992) Hepatoblastoma: The Prognostic Significance of Histologic Type, Pediatric Pathology, 12:2, 167-183 To link to this article: http://dx.doi.org/10.3109/15513819209023293
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Date: 31 October 2015, At: 07:09
HEPATOBLASTOMA: The Prognostic Significance of Histologic Type
Richard M. Conran, Maj, MC, USA
0 Department of Pediatric Pathology, Armed Forces Institute of Pathology, Washington, D . C . 20306-6000
Charles L. Hitchcock, Maj, MC, USAF 0 Department of Cellular Pathology, Armed Forces Institute of Pathology, Washington, D . C . 20306-6000 Myron A. Waclawiw, PhD
0
NHLBI, Biostatistic Research Branch,
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Bethesda, Maryland 20892
J. Thomas Stocker, COI, MC, USA
0
Armed Forces Institute of
Pathology, Washington, D . C . 20306-6000
Kamal G. Ishak, MD, PhD 0 Department of Hepatic and Gastrointestinal Pathology, Armed Forces Institute of Pathology, Washington, D.C. 20306-6000
0 The clinicopathologicfeatures of 105 hepatoblastomas accessioned to the Armed Forces Institute of Pathology between 1967 and 1987 were reviewed. D N A content was analyzed by flow cytometty. A multivariate analysis using the Cox proportional hazards model was perfoned to evaluate the effect of stage, histologic type, and D N A content on the prognosis for survival. The relative risks of death for a given stage compared to the other stages combined were 0.1637, 0.5672, 2.8742, and 3.5148 for stages I - I v respectively. The relative risk of death for a given histologic ype adjusted for age, sex, and stage compared to the other types was I . 0739 (p ,8850)for the fetal pattern, I . 7409 (p = ,1662) for the embryonal pattern, 0.5292 (p ,0754) for the mixed pattern, 1.1980 (p ,7729) for the macrotrabecular pattern, and 3.7096 (p ,1061) for the small-cell undigerentiated pattern. Of 19 hepatoblastomas analyzed for D N A content, 5 were D N A diploid and I 1 were D N A aneuploid; 3 could not be class$ed. The stage of disease at presentation proved to be a significant prognostic factor, whereas histologic type and D N A content did not have a significant effect.
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KEY WORDS: hepatoblastoma, liuer tumor, flow cytometry.
The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Departments of the Army, Air Force, or Defense. Presented in part at the Society for Pediatric Pathology Annual Meeting, March 3-4, 1990, Boston. Conran RM, Stocker JT, Ishak KG. Hepatoblastoma: 1967-1987. (Abstract) Mod Pathol 1990;3:2P. Address reprint requests to: Editorial Office, Armed Forces Institute of Pathology, Washington, DC 20306-6000.
Pediatric Pathology, 12:167-183, 1992 Copyright @ 1992 by Hemisphere Publishing Corporation
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Hepatoblastoma (HB) is a unique neoplasm of childhood with an annual incidence of 1 per million children. A review (1) of 35 HBs accessioned to the Armed Forces Institute of Pathology (AFIP) between 1927 and 1967 identified two basic histologic types: an epithelial type, with a fetal or embryonal pattern or combination of both, and a mixed type, which contained primitive mesenchymal cells in addition to the epithelial component. Following this report, Kasai and Watanabe (2) described a third distinctive pattern, the anaplastic pattern, more recently referred to as the small-cell undifferentiated pattern (3). A fourth distinct pattern, macrotrabecular, was subsequently described by Gonzalez-Crussi et al. (4). A variant of the mixed type of hepatoblastoma, first reported by Misugi and Reiner (5), contains elements from all three germ layers and has been named teratoid HB by Manivel et al. (6). Many reviews have attempted to correlate histologic type with prognosis (1, 2, 4, 7-12), a number suggesting that the pure fetal pattern had a better prognosis (2, 7, 9, 12). Weinberg and Finegold (9) in a review of 27 HBs reported that the prognostic effect of histologic type was based on the epithelial and not the mesenchymal component and that the pure fetal pattern had a better prognosis that the other types. Schmidt et al. (10) studied 24 HBs and observed no difference between the fetal and embryonal patterns. A limitation of these studies was that they did not adjust for clinical stage. Haas et al. (12) reviewed 168 HBs classified on the basis of their epithelial component alone and found an excellent prognosis for stage I (complete resection) HB that had a pure fetal pattern. No prognostic effect for histologic type was observed for stage 11-IV (incomplete resection) HBs; however, the presence of osteoid was a positive prognostic feature for this group. Because of our interest in this neoplasm, the controversy outlined above, and our bias of classifying HB on the basis of both the epithelial and mesenchymal components, we reviewed the clinicopathologic features of 105 HBs accessioned to the AFIP between 1967 and 1987. The prognostic significance of stage, histologic type, and DNA content for survival was evaluated.
METHODS The clinical summaries, surgical pathology and autopsy reports and submitted slides for 105 HBs were reviewed. Follow-up information was obtained from the submitting institutions. Ninety-two cases were submitted as surgical specimens and 13 as autopsy specimens. The number of slides submitted per case ranged from 1 to 24. The mean slide to maximum tumor diameter ratio was 0.71 with a standard deviation of 0.69 for all cases reviewed and a mean of 0.72 with a standard deviation of 0.61 for completely resected (stage I) HBs. The maximum tumor
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diameter was recorded for 36 of 45 completely resected and 35 of 60 partially resected or unresected HBs. Hepatoblastomas were initially classified on their epithelial and mesenchymal components into one of six histologic types (Table 1). The same tumors were alternatively classified on their epithelial component alone into one of four histologic types in order to assess the significance of histologic type for prognosis. Ten HBs could not be classified due to limited material or chemotherapy-induced changes and are designated as HB NOS (hepatoblastoma-not otherwise specified). When HBs were classified on their epithelial component alone, 11 were designated HB NOS. For the purpose of this study, the fetal pattern refers to an HB where 100% of the tumor is composed of small, round, uniform cells with abundant cytoplasm and distinct cytoplasmic membranes. The cells are arranged in thin trabeculae, usually two to three cells thick, with alternating light and dark areas (Fig. 1). The embryonal pattern refers to an HB where any part of the tumor has cells arranged in sheets of irregular, angulated cells with a high nucleocytoplasmic ratio, increased nuclear chromatin, and indistinct cytoplasmic membranes, Pseudorosette and acinar formation are common features (Fig. 2). Foci of extramedullary hematopoiesis are seen in both the fetal and embryonal areas. The macrotrabecular pattern refers to an HB in which trabeculae more than 10 cells thick are present as a repetitive pattern. The large trabeculae contain either fetal or embryonal type cells, or a third larger cell type with cytoplasm that is more abundant than in normal hepatocytes or fetal type cells, or a combination of all three cell types (Fig. 3). An HB with embryonal or mesenchymal cells and only an isolated rnacrotrabecular focus was classified on the embryonal or mesenchymal cell component present and not as macrotrabecular. The small cell pattern consists of a diffuse population of small cells with TABLE 1. Histologic Classification of Hepatoblastoma Based on Epithelial and Mesenchymal Components
I.
Epithelial type A. Fetal pattern B. Embryonal pattern C . Macrotrabecular pattern D. Small cell undifferentiated pattern 11. Mixed epithelial and mesenchymal type A. Mixed pattern without teratoid features B. Mixed pattern with teratoid features 111. HB NOS (not otherwise specified)
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FIGURE 1. Hepatoblastoma: fetal pattern. (a) Low-magnification photograph showing alternating light and dark areas. X 75. (b) Uniform population of cells with abundant vacuolated (light area) or granular (dark area) cytoplasm, distinct cytoplasmic membranes, and small round nuclei characterizes the fetal pattern. Extramedullary hematopoiesis (arrow) is present. X 300.
scant cytoplasm and indistinct cytoplasmic membranes, resembling neuroblastoma cells (Fig. 4). Areas of other recognizable HB patterns must be present before a diagnosis of the small cell variant is made. The mixed pattern has a combination of fetal or embryonal patterns intermixed with primitive spindled mesenchymal cells. Osteoid-like material is a common component in the majority of mixed HBs (Fig. 5). The mixed pattern with teratoid features contains the above epithelial and mesenchymal elements, as well as various combination of foci of mature cartilage, skeletal muscle, intestinal-type and keratinized squamous epithelium, and melanin pigment (Fig. 6 ) . For survival analysis, 11 cases that consisted of 4 intraoperative deaths, 3 perioperative deaths secondary to hemorrhage and infection, 3 deaths secondary to liver rupture at presentation, and 1 neonatal death were excluded. The remaining 94 cases were staged as outlined in Table 2 (12). Four cases that were lost to follow-up within 2 years of diagnosis were excluded in the computation of .the 2-year disease-free survival rates for histologic type, stratified by stage.
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The Cox Proportional Hazards model (13) was used to evaluate stage = 94), histologic type (N = 84), and DNA content (N = 19) for their prognostic effect on survival. Hepatoblastomas designated as HB NOS were not included in the study of the relative risk of death for histologic type. Because of limited numbers of incompletely resected HBs, stages 11-IV were combined for the analysis of the relative risk of death for histologic type, stratified by stage. A P value < .05 was considered statistically significant. In order to obviate sampling error in the cases represented by a single slide, the relative risk of death for histologic type was done initially on all cases (N 84) and then repeated on all cases with more than one slide (N 66). Both analyses yielded consistent estimates and conclusions. Henceforth, results based on N = 84 are presented. Initial review of the relative risk of death showed no significant difference (RR = .4419, P = .1667) between the mixed type without teratoid features and the mixed type with teratoid features; they were therefore combined and listed as mixed type and are also listed separately in Tables 6 and 7 . Nineteen HBs were submitted for flow cytometry. Technical aspects have been reported (14). T h e DNA content of the isolated nuclei obtained from areas of tumor and nonneoplastic liver was measured on an EPICS 541 flow cytometer (Coulter Cytometry, Hialeah, Florida) equipped with a 5-W argon laser used at an excitation wavelength of 488 nm. At least 2 X lo4 nuclei
(N
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FIGURE 2. Hepatoblastoma: embryonal pattern. Angulated cells with hyperchromatic nuclei, minimal cytoplasm, and indistinct cytoplasmic membranes form irregular rosettes. X 300.
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FIGURE 3. Hepatoblastoma: macrotrabecularpattern. (a) Large trabeculae more than 10 cells thick (top) are present adjacent to fetal area (bottom). X 75. (b) The cells making up the rnacrotrabeculae are more variable in size than the cells in the fetal pattern (compare with Fig. 1). X300.
per sample were collected at a flow rate of no more than 100 events per second for each DNA histogram. The effects of debris and doublets were minimized by gating on the peak and integrated red signals. Light scatter and red fluorescence signals were collected in list mode. All DNA histograms were analyzed by one of us (C.L.H.) without knowledge of the histologic type, stage, or patients' clinical course. Tumors were classified as DNA diploid (single GO/G1 peak) or DNA aneuploid (distinct second GO/G1 peak). In several cases, definition of the DNA aneuploid cell population required separation of subpopulations of nuclei based on their forward angle light scatter (FALS) and right angle (90') light scatter signals. List mode data were played back and single-parameter DNA histograms were derived from gating on different populations based on their light scatter properties. DNA analysis was calculated using the CytoLogic computer program (version 2.1, Coulter Cytometrics).
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RESULTS Clinical Features The age at diagnosis, sex, anL race of the 105 HB cases reviewed were similar to those previously reported (1). Clinical features and laboratory data were also similar. Most HBs (95%) were not associated with underlying liver disease, and only one HB was associated with a concurrent second malignancy (adrenal carcinoma) at diagnosis.
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Gross Features The gross features of the HBs reviewed were also similar to those previously reported (1). There was no difference in the maximum tumor diameter between completely resected HBs (mean 9 . 8 7 cm, SD 2 . 5 7 ) and partially or nonresected HBs (mean 9 . 3 0 cm, SD 2 . 7 3 ) .
Histologic Features The 105 HBs, when classified on the basis of both their epithelial and mesenchymal components, were distributed into the following histologic types: fetal 2 8 % , embryonal 1 7 % , mixed without teratoid features 3 1 % ,
FIGURE 4. Hepatoblastoma: small cell pattern. This diffuse population of small cells has hyperchromatic nuclei, a high nucleocytoplasmic ratio, and indistinct cytoplasmic membranes.
X
300.
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FIGURE 5. Hepatoblastoma: mixed pattern. (a) Epithelial elements are intermixed with primitive mesenchymal cells (M) and osteoid-like material (arrows). X 75. (b) Spindle-shaped mesenchymal cells separate foci of osteoid-like material. X 300.
mixed with teratoid features 9%, macrotrabecular 3 7% , small cell 3 % , and HB NOS 9 % . The percentage of fetal and embryonal HBs in the current study was similar to that previously reported (1). With the addition of the macrotrabecular and small cell patterns since 1967, the percentage of mixed HBs (which includes those with teratoid features) decreased from 54 to 40%. When the same tumors were classified on the basis of their epithelial component alone, the following distribution was obtained: fetal 2976, embryonal 55 76,macrotrabecular 3 % , small cell 3 % , and HB NOS 10 % . The percentage of fetal, small cell, and macrotrabecular HBs remained constant between the two classifications, whereas the percentage of embryonal HBs increased when the epithelial component alone was considered. Fetal HBs for the most part showed features similar to those previously reported; however, in a number of cases the fetal cells appeared to be similar in size to the surrounding nonneoplastic hepatocytes rather than being smaller. Mitotic figures for the most part were scarce; however, there were isolated tumors with a mitotic rate
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FIGURE 6. Hepatoblastoma: mixed pattern with teratoid features. (a) Keratinized squamous epithelium (arrow) adjacent to osteoid-like material ( X 75), (b) intestinal-type epithelium ( X 150), (c) striated muscle cells ( X 300), and (d) melanin pigment ( X 300) are some of the teratoid elements seen in this pattern.
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TABLE 2. Staging Classification Stage I Stage I1
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Stage 111 Stage IV
Complete resection Microscopic residual, negative nodal involvement, no spilled tumor Gross residual or nodal involvement or spilled tumor Metastatic disease
of up to 24 mitoses per 1.96 mm2 (10 high-power fields). Extramedullary hematopoiesis varied among tumors. In most fetal HBs, trabeculae were two or three cells thick, although trabeculae four to eight cells thick could be seen occasionally, but a repetitive pattern was not identified. All embryonal HBs in our study contained both fetal and embryonal areas. No pure embryonal HB was identified. The three HBs that were classified as macrotrabecular contained both fetal and embryonal cells in the trabeculae. One of the three contained very large cells similar to those seen in hepatocellular carcinoma. All but one mixed HB contained both fetal and embryonal patterns as the epithelial component. The one exception contained only fetal cells in association with the mesenchymal elements; however, only two slides were available for review from that tumor. The nonneoplastic liver was normal in 91 % (63 of 69) of the cases when present on the slides reviewed. Portal fibrosis, fatty change, and cirrhosis were the pathologic processes present in the six cases with abnormal livers.
Flow Cytometry One to two blocks per case from 19 HBs were submitted for DNA analysis by flow cytometry. Of the 19 cases, 3 yielded uninterpretable histograms, 5 were DNA diploid, and 11 had a DNA aneuploid stemline present. No correlation was observed between DNA ploidy and stage or histologic type (Table 3). Prognosis Of the 94 HBs for which survival data were available, the cases were distributed into the following stages: stage I 48%, stage I1 7%, stage I11 27%, and stage IV 18%. Eighty-two percent (56 of 68) of patients reported receiving adjuvant chemotherapy; however, only 56% (19 of 34) of stage I patients reported its use. Eight of the 68 patients had also received chemotherapy, preoperatively, to reduce the size of the tumor prior to excision. Thirty-five percent (24 of 68) of patients also reported use of radiotherapy in conjunction with chemotherapy. Four of the patients were lost to follow-up during the first 2 years after
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TABLE 3. Flow Cytometric Analysis of HBs: Distribution by Stage and Histologic Type
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Stage" Histologic type
I
Fetal Embryonal Mixed Mixed teratoid Macrotrabecular Small cell
3A,2D 2A 2D 1A 1A
I1
I11
IV
1A 1D 1A
1A 1A
'A, DNA aneuploid; D, DNA diploid.
diagnosis. Forty-seven of the remaining 90 patients were alive 2 years after diagnosis; 45 were disease free and 2 were alive with disease. The 2-year disease-free survival was better for stage I tumors (81%) than for the other stages (stage I1 66%, stage 111 21%, stage IV 18%). Survival by histologic type (Table 4) was good for stage I fetal and mixed HBs and stage 11-IV mixed HBs. The 2-year disease-free survival by histologic type for HBs classified on their epithelial component alone showed the following distributions: stage I (fetal 94%, embryonal 67 %, macrotrabecular 0%) and stages 11-IV (fetal 11 % , embryonal 32 % , macrotrabecular 0 % , and small cell undifferentiated 0%). The relative risk of death for stage (Table 5) indicates a good prognosis for stage I HBs and a poor prognosis for stage I11 and IV HBs relative to the other stages combined. No significant effect was observed in the relative risk of death for histologic type when adjusted for age, sex, and stage (Tables 6 and TABLE 4. Percent Survival' for Given Histologic Typeb Stratified by Stage
Histologic type
All stages
Fetal Embryonal Mixedd Mixed teratoid Macrotrabecular Small cell undifferentiated HB NOS
64 (25)' 31 (13) 61 (28) 44 (9) 0 (3) 0 (2) 50 (10)
Complete resection (stage I)
Incomplete resection (stages 11-IV)
93 (16) 57 (7) 91 (11) 50 ( 6 ) 0 (1)
-
100 (2)
"Alive without disease for a minimum of 2 years; excludes intraoperative/perioperativedeaths (1 1) and four cases lost to followup during first 2 years after diagnosis. 'Cases classified on their epithelial and mesenchymal components. 'Number in parentheses represents the number of cases in that stage. dRepresents mixed HB without teratoid features.
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TABLE 5. Relative Risk of Death for Given Stage",' Stage
Relative risk
P value
I I1 111 IV
0.1637 0.5672 2.8742 3.5148
< .00001 ,4375 ,0013 ,0002
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'Stage of interest compared to other stages combined. 'Cases adjusted for age and sex.
8), but when cases were adjusted for age and sex, but stratified by stage (Tables 7 and 9), the macrotrabecular and small cell types were associated with a poorer prognosis. The fetal type did not demonstrate a positive prognostic effect, regardless of whether the tumors were classified on their epithelial component alone or on the combination of their epithelial and mesenchymal components. For the mixed HBs (Table 6), the relative risk of death for the mixed HBs without teratoid features compared to all other types was .4685 (P = .0542), demonstrating a borderline significant positive prognostic effect. When the cases were stratified by stage (Table 7), the positive prognostic effect was not seen for completely resected HBs but was present for incompletely resected lesions. The relative risk of death for DNA diploid versus DNA aneuploid tumors adjusted for age, sex, and stage was .0012 but was not significant (P = .7909). DNA content was not a factor in terms of survival.
DISCUSSION
A number of studies have appeared in the literature after our initial report of 35 HBs from this institution (1). Most of them, however, have been case TABLE 6. Relative Risk of Death for Given Histologic Type" for Cases Classified on Both Epithelial and Mesenchymal Components' Histologic type
Relative risk
Fetal Embryonal Mixed' Without teratoid features With teratoid features Macrotrabecular Small cell
1.0739 1.7409 0.5292 0.4685 1.1274 1.1980 3.7096
P value ,8850 ,1662
,0754 .0542 .8128 .7729 .lo61
"Histologic type of interest compared to other histologic types. 'Cases adjusted for age, sex, and stage. 'Includes all mixed HBs with and without teratoid features.
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TABLE 7. Relative Risk of Death for Given Histologic Type" for Cases Classified on Their Epithelial and Mesenchymal Components and Stratified by Stageb
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Complete resection (stage I)
Incomplete resection (stages 11-IV)
Histologic type
Relative risk
P value
Relative risk
P value
Fetal Embryonal Mixed' Without teratoid features With teratoid features Macrotrabecular Small cell
0.0000002 2.8376 1.4532 0.2970 5.1847 38.8375
,5292 ,1670 .6177 ,2645 ,0263 ,0292
1.6645 1.5956 0.3862 0.4011 0.7503 1.2869 5.4366
.3216 ,3334 ,0242 ,0429 ,7037 ,7320 ,0346
"Histologic type of interest compared to other histologic types. *Cases adjusted for age and sex, stratified by stage. 'Includes all mixed HBs with and without teratoid features.
reports or small series of less than 30 cases, precluding accurate survival analysis. Submission of cases to study groups (Pediatric Oncology Group, POG; Childrens Cancer Study Group, CCSG; Armed Forces Institute of Pathology, AFIP) has resulted in larger numbers of cases being available for review. These studies, however, are limited by the gross description and number of slides submitted for review. In order to investigate the prognostic significance of histologic type, we reviewed 105 HBs submitted to the AFIP over the last 20 years. Stage at presentation, histologic type, and relative DNA content were analyzed for their effect on prognosis. Stage at presentation was the most important factor. The relative risk of death for stage I HBs compared to the other stages combined demonstrated a good prognosis. The lack of significance for stage I1 HBs (P = .4375) is probably related to the small number of cases). The effect of adjuvant chemotherapy on survival was not addressed in this study because of the variation in treatment protocols employed over the 20TABLE 8. Relative Risk of Death for Given Histologic Type' for Cases Classified on Their Epithelial Component Only* Histologic type
Relative risk
P value
Fetal Embryonal Macrotrabecular Small cell
1.0188 0.7446 1.2223 3.6878
,9702 ,4468 ,7488 ,1085
"Histologic type of interest compared to other histologic types. *Cases adjusted for age, sex, and stage.
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TABLE 9. Relative Risk of Death for Given Histologic Type' Classified on Epithelial Component Alone and Stratified by Stageb
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Complete resection (stage I)
Incomplete resection (stages 11-IV)
Histologic type
Relative risk
P value
Relative risk
P value
Fetal Embryonal Macrotrabecular Small cell
0.0000001 7.9260 38.8375
,5010 .0986 ,0292
1.7058 0.4313 1.3004 5.3602
,3045 ,0642 .7218 ,0367
-
-
"Histologic type of interest compared to other histologic types. k a s e s adjusted for age and sex, stratified by stage.
year period when the cases were collected. Twenty percent (8 of 40) of longterm survivors in this study, however, did not receive any chemotherapy. Utilizing a P value of less than .05 as a level of significance, we did not identify one histologic type as being superior to any other in terms of survival. The pure fetal pattern stage I and the mixed pattern both demonstrated good survival when the 2-year disease-free interval stratified by stage was considered. However, when a multivariate analysis is performed adjusting for variables such as stage and cases lost to follow-up, no significant difference in survival for histologic type was observed, regardless of whether the tumors were classified on their epithelial component alone or on their mesenchymal and epithelial components combined. The mixed histologic pattern (cases with and without teratoid features) had a borderline significantly positive prognostic effect on survival. We addressed the question of whether we should separate the mixed HBs without teratoid features from the mixed HBs with teratoid features. The percentage of cases with 2-year survival differs between the two groups, suggesting a better prognosis for the mixed HBs without teratoid features. We found, however, no significant difference in the relative risk of death between these two groups. We feel that analysis of a larger number of mixed HBs with teratoid features is needed to determine whether they behave differently from the mixed type without teratoid features and whether they should be considered as two separate groups. None of the mixed HBs with teratoid features were associated with preoperative chemotherapy in this study. When the mixed HBs as a group were stratified, but not adjusted for stage, the mixed HBs for incompletely resected lesions had a good prognosis. This is consistent with the CCSG observation (12) of the positive prognostic effect of osteoid for incompletely resected HBs. The macrotrabecular and small cell patterns appear to have a poor prognosis; the number of small cell and macrotrabecular HBs in our study is too small to draw a meaningful conclusion, but this is consistent with the reports of others.
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O u r observations are similar to those of Schmidt et al. (lo), who noted no difference between the fetal and embryonal patterns. Also, we agree with the original impression of Ishak and Glunz (1) and that of Dehner (8) about the good effect of the mixed pattern. In contrast to the view of Weinberg and Finegold (9), we favor continuing to classify HBs on both their epithelial and mesenchymal components because of the prognostic significance of the osteoid-like material and mesenchymal elements. O u r data do not support the view of Haas et al. (1 2) that the pure fetal pattern for completely resected HBs by itself has a positive prognostic value. Although the HBs in their study were classified on the epithelial component alone and a P value < .1 was considered significant, we did not find a positive prognostic value for our cases when classified on the epithelial component alone at a significance level of < .1. This discrepancy may be due in part to inaccurate classification. Adequate sampling, as recommended by Gonzalez-Crussi et al. (4), was a weakness of both studies. This presents a problem in classifying the fetal pattern as pure fetal. In order to diminish inadequate sampling as a reason for the discrepancy, we performed the same analysis excluding all cases for which only one slide was available for review. Similar results were obtained. Also, as in the study of Lack et al. (7), we found that we could not classify 10% of our HBs because of the type of specimen (needle biopsy) or chemotherapy effect. The CCSG (12) did not report this as a problem in their study. Variations in interpretation of histologic criteria could be another problem. We interpret a number of observations in the literature about the positive prognostic effect of the fetal pattern to be related to stage and not histology. The prognostic significance of DNA ploidy, oncogenes, and tumor cytogenetics is an area of recent interest. DNA content has been shown to be of prognostic value in a number of malignancies (15); however, its prognostic role in pediatric solid tumors is still being defined. Two exceptions are neuroblastoma and Wilms’ tumor (16-18). Flow cytometric analyses of pediatric liver tumors are limited. The only HB flow cytometric analysis that we are aware of is the report by Orozco-Florian et al. (19) on a DNA aneuploid congenital HB in a patient with Beckwith-Wiedemann syndrome who died at 2 weeks of age. Leuschner et al. (20) reported that four of five cases of undifferentiated sarcoma of the liver were DNA diploid and the other DNA aneuploid; the DNA aneuploid tumor had a poorer prognosis. We submitted approximately 20% of our cases for flow cytometry and found that DNA content was not a significant prognostic factor. Further study using larger numbers of cases is needed, but our preliminary data indicate that DNA content is not a prognostic factor and does not correlate with histologic type. Amplification of c-myc and. N-myc oncogenes, associated with a poor prognosis in neuroblastoma, was not observed in 10 HBs examined by Tsuda et al. (21). Tumor cytogenetic analysis has been reported in four HBs with a mixed pattern (22).
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Abnormalities of chromosomes 2 and 20 were identified. The prognostic significance of the observed karyotypes was not addressed. In summary, stage at presentation and the ability to resect the tumor completely appear to be the most important prognostic factors at this time. Hepatoblastoma is a tumor with a spectrum of histologic patterns. We favor continuing to classify the tumor on the basis of both the epithelial and mesenchymal components. We did not document that one histologic type was superior to the others, although the mixed HB appears to have the best overall survival. DNA content was not a prognostic factor.
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ReceivedJune 17, 1991 Revition Accepted Aufust 22, 1991
