460
0 1992 The Japanese Society of
Pathology
Cytogenetic Characteristics of a Malignant Rhabdoid Tumor Arising from the Paravertebral Region A Case Report
Hiroshi Horie’, Takao Etoh’, and Masahiko Maie’
The pathological and cytogenetic features of an extrarenal malignant rhabdoid tumor (MRT) arising from the paravertebral region in an infant were investigated. The patient died 4 months after diagnosis, due to aggressive tumor progression. The tumor was composed of medium-sized round cells with cytoplasm containing eosinophilic inclusions, which ultrastructurally were composed of densely packed whorled intermediate filaments. Flow-cytometric analysis of the tumor cells revealed a diploid pattern. Amplification of the N -myc oncogene was not identified. lmmunohistologically, the inclusion bodies showed a positive reaction with antiserum against vimentin. The tumor cells were not reactive with antiserum against epithelial membrane antigen, anti-keratin (polyclonal) or cytokeratin (monoclonal, CKI), but did react with 5H10,an antiserum established from human sarcomatous Wilms’ tumor. This case is discussed with reference to the literature on extrarenal MRT, placing stress on the histogenesis of this tumor. Acta Pathol Jpn 42 : 460-465, 1992. Key words : Malignant rhabdoid tumor, Paravertebral, Extrarenal, Case report
Malignant rhabdoid tumor (MRT) is a rare malignancy of the kidney, usually seen in childhood, which was initially described as a variant of Wilms’ tumor with unfavorable prognosis (1, 2). The neoplastic cells have a large cytoplasm with eosinophilic inclusion bodies, resembling rhabdomyoblasts in rhabdomyosarcoma, although MRT is now regarded as an entity separate from ordinary Wilms’ tumor. Ultrastructurally, the inclusions are composed of whorls of intermediate ~ _ _ _
Received August 28, 1991. Accepted for publication January 28, 1992 Divisions of ’Pathology and LPediatric Surgery, Chiba Children’s Hospital, Chiba Mailing address: Hiroshi Horie, M.D., Division of Pathology, Chiba Children’s Hospital, 579 1 Heta-matt, Midori-ku, Chiba 266, Japan
filaments (2). Recently, identical tumors arising from various extrarenal locations have been described, e.g., the liver, chest wall, paravertebral region, inguinal area, pelvic cavity, prostate and heart (3-8). The histogenesis of MRT of the kidney is still unclear, as is that of the extrarenal varieties, but it is proposed that the latter is a heterogenous entity (9, 10). In this paper, we report an extrarenal MRT, with details of ultrastructural, immunohistochemical, flow-cytometric and southern blot DNA analysis.
CLINICAL SUMMARY A 4-month-old girl was admitted to our hospital because of a dorsal soft-tissue mass. Her parents had noticed paralysis of her lower legs one month earlier. Radiographic examination and magnetic resonance imaging revealed a tumor arising from the lower thoracic vertebrae with infiltration into the subcutaneous tissue of the left paravertebral area. The tumor also extended through the intervertebral foramina into the intraspinal canal, forming a dumbbell-shaped mass, resulting in compression of the spinal cord (Fig. 1). Aspiration cytologic examination revealed atypical neoplastic cells, suggestive of sarcoma. Semiemergency laminectomy and removal of the extradural tumor were performed. The subcutaneous neoplastic mass was also excised, but complete elimination of the neoplastic tissue was not accomplished. Postoperatively the patient received chemotherapeutic agents, but metastatic manifestations developed, including the appearance of pleural effusion containing the neoplastic cells, and hydrocephalus due to meningeal involvement. Four months after surgery, the neoplastic tissue invaded the left thoracic cavity, and the patient died of respiratory fa iIure. Autopsy revealed a huge tumor mass occupying the left thoracic cavity, with metastases in the left lung,
Acta Pathologica Japonica 42 (6) : 1992
461
cerebellar hemisphere, and liver. There was, however, no evidence of neoplastic change in either kidney.
PATHOLOGICAL FINDINGS
Figure 1. T1-weighted image of intraspinal invasion by the tumor.
coronal
section
reveaIIS
Neoplastic tissue excised from the dorsal region of the patient consisted of relatively uniform medium-sized cells, with eccentric round or polygonal nuclei, each containing a single large prominent nucleolus. Characteristically, the neoplastic cells had eosinophilic hyaline inclusions in the cytoplasm (Figs. 2, 3). The inclusion bodies were either PAS-negative or weakly positive, and were stained pale blue with Masson's trichrome. Neoplastic multinucleated giant cells were observed occasionally. Most of the tumor cells removed from the intraspinal canal showed necrotic change. Electron microscopic examination disclosed that the inclusions were composed of closely packed intermediate
Figure 2. Tumor cells invading the subcutaneous tissue of the dorsum and muscular tissue in the paravertebral region (HE).
Figure 3. Tumor cells with eosinophilic hyaline inclusions in the cytoplasm and prominent nucleoli (HE).
4 62
Extrarenal Malignant Rhabdoid Tumor (Hot,ie et a/.)
Figure 4. lntracytoplasmic inclusion, composed of closely packed intermediate filaments, arranged in a whorled pattern (electron microscopy, 11,400 x ) .
Figure 5. lntracytoplasmic inclusion bodies showing positive staining with antiserum against vimentin (PAP).
Figure 6. Tumor cells showing positive reactivity with antibody 5H10 against sarcomatous Wilms’ tumor (PAP).
463
Acta Pathologica Japonica 4 2 (6) : 1992
)
0
I
I
I
I& I
~
200
I
I
l 1
1
1
"
400
I I b ik l " l I I 600 800 1000
DNA Figure 7. Frozen tumor tissue was obtained during surgery. The tumor cell DNA histogram shows only a single Gl/GO peak in the diploid range.
A
6
staining with anti-vimentin (monoclonal antibody, DAKO) (Fig. 5), but negative staining with antineurofilament (monoclonal, DAKO), anti-N-myc product (polyclonal, MBL), anti-S100 (polyclonal, DAKO), antimyoglobin (polyclonal, DAKO), anti-desmin (monoclonal, DAKO), anti-leukocyte common antigen (LCA) (monoclonal, DAKO), anti-lysozyme (polyclonal, DAKO), antikeratin (polyclonal, DAKO), ant i-cyto kerat in (monoclonal, CK1, DAKO) and anti-epithelial membrane antigen (EMA) (monoclonal, DAKO). Strong positive reactivity was observed on the cell surface with 5H10, as antibody against a sarcomatous Wilms' tumor (11) (Fig. 6). Ant i-neuron-specif ic eno la se (N SE) (pol yclona I, DAKO) gave a weakly positive reaction, and anti-alpha1-anti-chymotrypsin (ACT) (polyclonal, DAKO) reacted with a few tumor cells. Flow-cytometric analysis of the frozen tumor tissue obtained during surgery demonstrated a diploid DNA content (Fig. 7). Southern blot analysis of the tumor cell DNA showed no amplification of the N-myc oncogene (Fig. 8).
C
DISCUSSION
UDh (3.2Kb)
N-myc (2.OKb)
Figure8. Southern blot analysis of the tumor cells. For comparison, DNA from neuroblastoma cell line IMR-32, with known N-myc amplification (25-fold), and normal placenta were analyzed. UDh probe: expresses part of non-functional human DNA. A : normal placenta, B : this tumor, C : IMR-32.
filaments 8-10 nm in diameter, arranged in a fascicular or whorled pattern (Fig. 4). No myofibrillar structure or cross-striation was identified. No epithelial or neuronal differentia tion was evident. lmmunohistochemically, the inclusions showed positive
Recently, a relatively large number of extrarenal MRTs have been reported (9, 12, 13), although in Japan, not more than 20 cases have been described (12,14, 15). The tumor cells are characterized by the presence of eosinophilic cytoplasm closely resembling that of rhab domyoblasts, although the cytoplasmic inclusions never show myogenic differentiation, either immunohistochemically or ultrastructurally. PAS reaction is also consistently either negative o r weakly positive, in contrast to the findings observed in rhabdomyosarcoma. While MRT was originally described in the kidney, there have been some reports of MRT arising from various other sites, as first described by Gonzalez-Crussi et a/. (3). Over 70 cases have been described in the literature, and most of the patients were either infants or adolescents, apparently forming two main age groups. Paravertebral occurrence of MRT has been reported by Lynch et a/. (4). Handgretinger et a/. (16) also described a case in a 17-month-old boy, who showed a clinical course quite similar t o that of our patient. In that case, the tumor showed intraspinal extension, resulting in paralysis of the left lower extremity. Following subtotal resection of the tumor, local recurrence and pleural metastases developed, and the patient died 4 months after diagnosis. Recently, a similar case arising from the paravertebral region was reported in Japan (15). For histopathological distinction of MRT from rhab domyosarcoma, PAS staining is practically useful. The
4 64
Extrarenal Malignant Rhabdoid Tumor (Horie et a/.)
present tumor showed a negative or faintly positive PAS reaction, as reported previously, in contrast to rhabdomyosarcoma, which usually exhibits unequivocal positive PAS staining. Although non-specific, the presence of intracytoplasmic eosinophilic inclusions, which stain blue with Masson's trichrome, is one of the most characteristic features, and these were present in this case. lmmmunohistochemical staining for vimentin is also helpful for diagnosis of MRT. The histogenesis of MRT is still unknown, partly because of its rare occurrence. In almost all of the reported cases, the intracytoplasmic inclusions of MRT showed staining for vimentin, suggesting a possible mesenchymal origin. However, positive staining for cytokeratin and EMA has also been described in many cases(12, 13). These results might be interpreted to indicate that the tumor has potential to differentiate into both epithelial and mesenchymal directions. Our histochemical examination, which included a digestive procedure and electron microscopy, did not support the tumor's epithelial differentiation. In the literature, several cases did not show divergent differentiation, as was the case here(9, 13). However, it can not be denied that staining reactivity is influenced by formalin fixation (17). Some investigators have documented the appearance of such filament-laden tumor cells in various neoplasms including those of epithelial, histiocytic or neuroendocrine origin (3, 18, 19). In our present case, a neural origin of the neoplasm was suspected initially because of its paravertebral location and positive NSE staining, but further convincing evidence for a neural origin was not obtained by either immunohistochemistry or electron microscopy. Epithelioid sarcoma is usually difficult to differentiate, but can be excluded on the basis of histological features, the age of the patient, and the location of tumor(l3). Lymphoid malignancy can be ruled out by the negative reaction to anti-LCA. Clinically and morphologically, there is no obvious difference between renal and extrarenal MRT, except that the former variety is more frequently associated with brain tumor(9). lshii et a/. (11) reported that renal MRT and tubules in the kidney in an early developmental stage had a common antigenicity, using monoclonal antibody 5H10, which was established from a sarcomatous variant of Wilms' tumor. The neoplastic cells in the present case reacted positively with 5H10. In addition, it has been reported that monoclonal antibody against Tamm-Horsfall protein, a glycoprotein elaborated by cells of the loop of Henle and distal convoluted tubule, showed a positive reaction in both renal and extrarenal MRT (20). These findings suggest a common origin of the two tumors. However, 5H10 also reacts with some rhabdomyosarcomas and Ewing's sar-
comas (11). This evidence suggests that 5H10 antigen is related to cell proliferation rather than cell differentiation. As the intracytoplasmic inclusions with a filamentous ultrastructural appearance seen in MRT have been reported in various other types of neoplasm, it has been stated that this structure is characteristic of MRT, but not specific for any single type of tumor (14). Weeks et a/. (21) considered extrarenal MRT to be a phenotypic manifestation that may or may not be related to MRT of the kidney. Flow-cytometric analysis of DNA from various type of neoplasm can provide information useful for prognostic evaluation. Flow cytometry in this case showed a d i p loid pattern. Schmidt et a/. (22) reported that none of 11 cases of MRT examined by flow cytometry revealed aneuploid DNA stem lines. Handgretinger et a/. (16) also demonstrated a diploid pattern in an extrarenal MRT, and this was associated with a reciprocal translocation between chromosomes 18 and 22. Similar results of DNA ploidy analysis have been reported for neuroblastomas with a poor clinical out look (23), which might suggest a somewhat limited role of DNA ploidy analysis in predicting the prognosis of some childhood neoplasms. Our present case was initially suspected to be neuroblastoma, and therefore southern blot analysis of N-myc oncogene amplification was done. However, no N-myc amplification was detected. Handgretinger et a/. (16) reported similar findings. This suggests a genetic difference between MRT and neuroblastoma. The histogenetic relationship between renal and extrarenal MRT still remains obscure, and elucidation of this aspect requires further investigation. Since the prognosis of MRT whether renal or extrarenal, is usually grave, and both tumors behave aggressively, MRT should be considered an important clinicopathological entity. '
Acknowledgements : The authors thank Prof. Jun-ichi Hata, Department of Pathology, Keio University School of Medicine, and Dr. Jun-ichiro Fujimoto, Department of Pathology, National Children's Medical Research Center, for their valuable suggestions regarding immunohistological examinations. We are also grateful to Dr. Masanori Matsunaga, Department of Pediatric Surgery, Chiba University School of Medicine, for assistance with Southern blot analysis of genomic DNA.
REFERENCES 1. Beckwith JB and Palmer NF. Histopathology and prognosis of Wilms' tumor. Results from the First
National Wilms' Tumor Study. Cancer 41: 19371948,1978. 2. Haas JE, Palmer NF, Weinberg AG, and Beckwith JB. Ultrastructure of malignant rhabdoid tumor of the kidney. A distinctive renal tumor of children. Hum
Acta Pathologica Japonica 42 (6) : 1992
3.
4. 5.
6.
7.
8. 9.
10.
11.
12. 13.
Pathol 1 2 : 646-657, 1981. Gonzalez-Crussi F, Goldshmidt RA, Hsueh W, et a/. Infantile sarcoma with intracytoplasmic filamentous inclusions. Distinctive tumor of possible histiocytic origin. Cancer 49 : 2365-2375, 1982. Lynch HT, Shurin BB, Dahms BB, et a/. Paravertebral malignant rhabdoid tumor in infancy. In vitro studies of a familial tumor. Cancer 52: 290-296, 1983. Tsujimura T, Wada A, Kawano K, lwasa A, and Mizutani S. A case of malignant rhabdoid tumor arising from soft parts in the prepubic region. Acta Pathol Jpn 39: 677-682, 1989. Frierson HF, Mills SE, and lnnes DJ. Malignant rhab doid tumor of the pelvis. Cancer 55: 1963-1967, 1985. Ekfors TO, Aho HJ, and Kekomaeki M. Malignant rhabdoid tumor of the prostatic region. Immunohistolog ica I and ultrastructura I evidence for epitheliaI origin. Virchows Arch [Pathol Anat] 406: 381-388, 1985. Small EJ, Gordon GJ, and Dahms BB. Malignant rhabdoid tumor of the heart in an infant. Cancer 55: 2850-2853, 1985. Sotelo-Avila C, Gonzalez-Crussi F, deMello D, et a/. Renal and extrarenal rhabdoid tumor in children. Clinicopathologic study of 14 patients. Semin Diagn Pathol 3 : 151-163, 1986. Tsokos M, Kouraklis G, Chandra RS, Bhagavan S, and Triche TJ. Malignant rhabdoid tumor of the kidney and soft tissues. Arch Pathol Lab Med 113: 115120, 1989. lshii E, Fujimoto J, Hara S, Tanaka S, and Hata J. Human sarcomatous Wilms' tumor. Characterization with 5H10, a newly established monoclonal antibody. Acta Pathol Jpn 39 : 656-663, 1989. Tuneyoshi M, Daimaru Y, Hashimoto H, and Enjoji M. The existence of rhabdoid cells in specified soft tissue sarcomas. Virchows Arch [A] 411 : 509-514, 1987. Kodet R, Newton WA, Sachs N, et a/. Rhabdoid tumors of soft tissues: A clinjcopathologic study of 26
14.
15. 16.
17.
18. 19. 2 0.
21.
2 2.
2 3.
4 65
cases enrolled on the intergroup rhabdomyosarcoma study. Hum Pathol 22: 674-684, 1991. Tsuneyoshi M, Daimaru Y, Hashimoto H, and Enjoji M. Malignant soft tissue neoplasm with the histologic features of renal rhabdoid tumors. An ultrastructural and immunohistochemical study. Hum Pathol 16: 1235-1 242, 1985. Kai B, Sakata N, ikuno K, et a/. A case of rhabdoid tumor. Shouni Gann 27 : 562, 1991 (in Japanese). Handgretinger R, Kimmig A, Koscielnak E, et a/. Establishment and characterization of a cell line (Wa2) derived from an extrarenal rhabdoid tumor. Cancer Res 50: 2177-2182, 1990. Battifora H and Kopinski M. The influence of protease digestion and duration of fixation on the immunostaining of keratins. J Histochem Cytochem 34: 1095-1 100, 1986. Carstens PBH and Broghamer WL. Duodenal carcinoid with cytoplasmic whorls of microfilaments. J Pathol 124 : 235-238, 1978. Weeks DA, Beckwith JB, and Mierau GW. Rhabdoid tumor. An entity or a phenotype? Arch Pathol Lab Med 113: 113-114, 1989. Kumar S, Jakate SM, Marsden HB, Kumar P, and Jasani B. Tamm-Horsfall protein is a marker of renal and extra-renal rhabdoid tumours. Int J Cancer 41 : 386-389, 1988. Weeks DA, Beckwith JB, Mierau GW, and Luckey DW. Rhabdoid tumor of kidney. A report of 111 cases from the National Wilms' Tumor Study Pathology Center, Am J Surg Pathol 1 3 : 439-458, 1989. Schmidt 0, Leuschner I, Harms D, Sprenger E, and Schafer H-J. Malignant rhabdoid tumor. A morphological and flow cytometric study. Pathol Res Pract 184: 202-210, 1989. Gansler T, Chatten J, Varello M, et a/. Flow cytometric DNA analysis of neuroblastoma. Correlation with histology and clinical outcome. Cancer 58 : 24532458, 1986.
0 1992 The Japanese Society of
Pathology
Cytogenetic Characteristics of a Malignant Rhabdoid Tumor Arising from the Paravertebral Region A Case Report
Hiroshi Horie’, Takao Etoh’, and Masahiko Maie’
The pathological and cytogenetic features of an extrarenal malignant rhabdoid tumor (MRT) arising from the paravertebral region in an infant were investigated. The patient died 4 months after diagnosis, due to aggressive tumor progression. The tumor was composed of medium-sized round cells with cytoplasm containing eosinophilic inclusions, which ultrastructurally were composed of densely packed whorled intermediate filaments. Flow-cytometric analysis of the tumor cells revealed a diploid pattern. Amplification of the N -myc oncogene was not identified. lmmunohistologically, the inclusion bodies showed a positive reaction with antiserum against vimentin. The tumor cells were not reactive with antiserum against epithelial membrane antigen, anti-keratin (polyclonal) or cytokeratin (monoclonal, CKI), but did react with 5H10,an antiserum established from human sarcomatous Wilms’ tumor. This case is discussed with reference to the literature on extrarenal MRT, placing stress on the histogenesis of this tumor. Acta Pathol Jpn 42 : 460-465, 1992. Key words : Malignant rhabdoid tumor, Paravertebral, Extrarenal, Case report
Malignant rhabdoid tumor (MRT) is a rare malignancy of the kidney, usually seen in childhood, which was initially described as a variant of Wilms’ tumor with unfavorable prognosis (1, 2). The neoplastic cells have a large cytoplasm with eosinophilic inclusion bodies, resembling rhabdomyoblasts in rhabdomyosarcoma, although MRT is now regarded as an entity separate from ordinary Wilms’ tumor. Ultrastructurally, the inclusions are composed of whorls of intermediate ~ _ _ _
Received August 28, 1991. Accepted for publication January 28, 1992 Divisions of ’Pathology and LPediatric Surgery, Chiba Children’s Hospital, Chiba Mailing address: Hiroshi Horie, M.D., Division of Pathology, Chiba Children’s Hospital, 579 1 Heta-matt, Midori-ku, Chiba 266, Japan
filaments (2). Recently, identical tumors arising from various extrarenal locations have been described, e.g., the liver, chest wall, paravertebral region, inguinal area, pelvic cavity, prostate and heart (3-8). The histogenesis of MRT of the kidney is still unclear, as is that of the extrarenal varieties, but it is proposed that the latter is a heterogenous entity (9, 10). In this paper, we report an extrarenal MRT, with details of ultrastructural, immunohistochemical, flow-cytometric and southern blot DNA analysis.
CLINICAL SUMMARY A 4-month-old girl was admitted to our hospital because of a dorsal soft-tissue mass. Her parents had noticed paralysis of her lower legs one month earlier. Radiographic examination and magnetic resonance imaging revealed a tumor arising from the lower thoracic vertebrae with infiltration into the subcutaneous tissue of the left paravertebral area. The tumor also extended through the intervertebral foramina into the intraspinal canal, forming a dumbbell-shaped mass, resulting in compression of the spinal cord (Fig. 1). Aspiration cytologic examination revealed atypical neoplastic cells, suggestive of sarcoma. Semiemergency laminectomy and removal of the extradural tumor were performed. The subcutaneous neoplastic mass was also excised, but complete elimination of the neoplastic tissue was not accomplished. Postoperatively the patient received chemotherapeutic agents, but metastatic manifestations developed, including the appearance of pleural effusion containing the neoplastic cells, and hydrocephalus due to meningeal involvement. Four months after surgery, the neoplastic tissue invaded the left thoracic cavity, and the patient died of respiratory fa iIure. Autopsy revealed a huge tumor mass occupying the left thoracic cavity, with metastases in the left lung,
Acta Pathologica Japonica 42 (6) : 1992
461
cerebellar hemisphere, and liver. There was, however, no evidence of neoplastic change in either kidney.
PATHOLOGICAL FINDINGS
Figure 1. T1-weighted image of intraspinal invasion by the tumor.
coronal
section
reveaIIS
Neoplastic tissue excised from the dorsal region of the patient consisted of relatively uniform medium-sized cells, with eccentric round or polygonal nuclei, each containing a single large prominent nucleolus. Characteristically, the neoplastic cells had eosinophilic hyaline inclusions in the cytoplasm (Figs. 2, 3). The inclusion bodies were either PAS-negative or weakly positive, and were stained pale blue with Masson's trichrome. Neoplastic multinucleated giant cells were observed occasionally. Most of the tumor cells removed from the intraspinal canal showed necrotic change. Electron microscopic examination disclosed that the inclusions were composed of closely packed intermediate
Figure 2. Tumor cells invading the subcutaneous tissue of the dorsum and muscular tissue in the paravertebral region (HE).
Figure 3. Tumor cells with eosinophilic hyaline inclusions in the cytoplasm and prominent nucleoli (HE).
4 62
Extrarenal Malignant Rhabdoid Tumor (Hot,ie et a/.)
Figure 4. lntracytoplasmic inclusion, composed of closely packed intermediate filaments, arranged in a whorled pattern (electron microscopy, 11,400 x ) .
Figure 5. lntracytoplasmic inclusion bodies showing positive staining with antiserum against vimentin (PAP).
Figure 6. Tumor cells showing positive reactivity with antibody 5H10 against sarcomatous Wilms’ tumor (PAP).
463
Acta Pathologica Japonica 4 2 (6) : 1992
)
0
I
I
I
I& I
~
200
I
I
l 1
1
1
"
400
I I b ik l " l I I 600 800 1000
DNA Figure 7. Frozen tumor tissue was obtained during surgery. The tumor cell DNA histogram shows only a single Gl/GO peak in the diploid range.
A
6
staining with anti-vimentin (monoclonal antibody, DAKO) (Fig. 5), but negative staining with antineurofilament (monoclonal, DAKO), anti-N-myc product (polyclonal, MBL), anti-S100 (polyclonal, DAKO), antimyoglobin (polyclonal, DAKO), anti-desmin (monoclonal, DAKO), anti-leukocyte common antigen (LCA) (monoclonal, DAKO), anti-lysozyme (polyclonal, DAKO), antikeratin (polyclonal, DAKO), ant i-cyto kerat in (monoclonal, CK1, DAKO) and anti-epithelial membrane antigen (EMA) (monoclonal, DAKO). Strong positive reactivity was observed on the cell surface with 5H10, as antibody against a sarcomatous Wilms' tumor (11) (Fig. 6). Ant i-neuron-specif ic eno la se (N SE) (pol yclona I, DAKO) gave a weakly positive reaction, and anti-alpha1-anti-chymotrypsin (ACT) (polyclonal, DAKO) reacted with a few tumor cells. Flow-cytometric analysis of the frozen tumor tissue obtained during surgery demonstrated a diploid DNA content (Fig. 7). Southern blot analysis of the tumor cell DNA showed no amplification of the N-myc oncogene (Fig. 8).
C
DISCUSSION
UDh (3.2Kb)
N-myc (2.OKb)
Figure8. Southern blot analysis of the tumor cells. For comparison, DNA from neuroblastoma cell line IMR-32, with known N-myc amplification (25-fold), and normal placenta were analyzed. UDh probe: expresses part of non-functional human DNA. A : normal placenta, B : this tumor, C : IMR-32.
filaments 8-10 nm in diameter, arranged in a fascicular or whorled pattern (Fig. 4). No myofibrillar structure or cross-striation was identified. No epithelial or neuronal differentia tion was evident. lmmunohistochemically, the inclusions showed positive
Recently, a relatively large number of extrarenal MRTs have been reported (9, 12, 13), although in Japan, not more than 20 cases have been described (12,14, 15). The tumor cells are characterized by the presence of eosinophilic cytoplasm closely resembling that of rhab domyoblasts, although the cytoplasmic inclusions never show myogenic differentiation, either immunohistochemically or ultrastructurally. PAS reaction is also consistently either negative o r weakly positive, in contrast to the findings observed in rhabdomyosarcoma. While MRT was originally described in the kidney, there have been some reports of MRT arising from various other sites, as first described by Gonzalez-Crussi et a/. (3). Over 70 cases have been described in the literature, and most of the patients were either infants or adolescents, apparently forming two main age groups. Paravertebral occurrence of MRT has been reported by Lynch et a/. (4). Handgretinger et a/. (16) also described a case in a 17-month-old boy, who showed a clinical course quite similar t o that of our patient. In that case, the tumor showed intraspinal extension, resulting in paralysis of the left lower extremity. Following subtotal resection of the tumor, local recurrence and pleural metastases developed, and the patient died 4 months after diagnosis. Recently, a similar case arising from the paravertebral region was reported in Japan (15). For histopathological distinction of MRT from rhab domyosarcoma, PAS staining is practically useful. The
4 64
Extrarenal Malignant Rhabdoid Tumor (Horie et a/.)
present tumor showed a negative or faintly positive PAS reaction, as reported previously, in contrast to rhabdomyosarcoma, which usually exhibits unequivocal positive PAS staining. Although non-specific, the presence of intracytoplasmic eosinophilic inclusions, which stain blue with Masson's trichrome, is one of the most characteristic features, and these were present in this case. lmmmunohistochemical staining for vimentin is also helpful for diagnosis of MRT. The histogenesis of MRT is still unknown, partly because of its rare occurrence. In almost all of the reported cases, the intracytoplasmic inclusions of MRT showed staining for vimentin, suggesting a possible mesenchymal origin. However, positive staining for cytokeratin and EMA has also been described in many cases(12, 13). These results might be interpreted to indicate that the tumor has potential to differentiate into both epithelial and mesenchymal directions. Our histochemical examination, which included a digestive procedure and electron microscopy, did not support the tumor's epithelial differentiation. In the literature, several cases did not show divergent differentiation, as was the case here(9, 13). However, it can not be denied that staining reactivity is influenced by formalin fixation (17). Some investigators have documented the appearance of such filament-laden tumor cells in various neoplasms including those of epithelial, histiocytic or neuroendocrine origin (3, 18, 19). In our present case, a neural origin of the neoplasm was suspected initially because of its paravertebral location and positive NSE staining, but further convincing evidence for a neural origin was not obtained by either immunohistochemistry or electron microscopy. Epithelioid sarcoma is usually difficult to differentiate, but can be excluded on the basis of histological features, the age of the patient, and the location of tumor(l3). Lymphoid malignancy can be ruled out by the negative reaction to anti-LCA. Clinically and morphologically, there is no obvious difference between renal and extrarenal MRT, except that the former variety is more frequently associated with brain tumor(9). lshii et a/. (11) reported that renal MRT and tubules in the kidney in an early developmental stage had a common antigenicity, using monoclonal antibody 5H10, which was established from a sarcomatous variant of Wilms' tumor. The neoplastic cells in the present case reacted positively with 5H10. In addition, it has been reported that monoclonal antibody against Tamm-Horsfall protein, a glycoprotein elaborated by cells of the loop of Henle and distal convoluted tubule, showed a positive reaction in both renal and extrarenal MRT (20). These findings suggest a common origin of the two tumors. However, 5H10 also reacts with some rhabdomyosarcomas and Ewing's sar-
comas (11). This evidence suggests that 5H10 antigen is related to cell proliferation rather than cell differentiation. As the intracytoplasmic inclusions with a filamentous ultrastructural appearance seen in MRT have been reported in various other types of neoplasm, it has been stated that this structure is characteristic of MRT, but not specific for any single type of tumor (14). Weeks et a/. (21) considered extrarenal MRT to be a phenotypic manifestation that may or may not be related to MRT of the kidney. Flow-cytometric analysis of DNA from various type of neoplasm can provide information useful for prognostic evaluation. Flow cytometry in this case showed a d i p loid pattern. Schmidt et a/. (22) reported that none of 11 cases of MRT examined by flow cytometry revealed aneuploid DNA stem lines. Handgretinger et a/. (16) also demonstrated a diploid pattern in an extrarenal MRT, and this was associated with a reciprocal translocation between chromosomes 18 and 22. Similar results of DNA ploidy analysis have been reported for neuroblastomas with a poor clinical out look (23), which might suggest a somewhat limited role of DNA ploidy analysis in predicting the prognosis of some childhood neoplasms. Our present case was initially suspected to be neuroblastoma, and therefore southern blot analysis of N-myc oncogene amplification was done. However, no N-myc amplification was detected. Handgretinger et a/. (16) reported similar findings. This suggests a genetic difference between MRT and neuroblastoma. The histogenetic relationship between renal and extrarenal MRT still remains obscure, and elucidation of this aspect requires further investigation. Since the prognosis of MRT whether renal or extrarenal, is usually grave, and both tumors behave aggressively, MRT should be considered an important clinicopathological entity. '
Acknowledgements : The authors thank Prof. Jun-ichi Hata, Department of Pathology, Keio University School of Medicine, and Dr. Jun-ichiro Fujimoto, Department of Pathology, National Children's Medical Research Center, for their valuable suggestions regarding immunohistological examinations. We are also grateful to Dr. Masanori Matsunaga, Department of Pediatric Surgery, Chiba University School of Medicine, for assistance with Southern blot analysis of genomic DNA.
REFERENCES 1. Beckwith JB and Palmer NF. Histopathology and prognosis of Wilms' tumor. Results from the First
National Wilms' Tumor Study. Cancer 41: 19371948,1978. 2. Haas JE, Palmer NF, Weinberg AG, and Beckwith JB. Ultrastructure of malignant rhabdoid tumor of the kidney. A distinctive renal tumor of children. Hum
Acta Pathologica Japonica 42 (6) : 1992
3.
4. 5.
6.
7.
8. 9.
10.
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