Results
Extrarenal Wilms’ Tumor: of the National Wilms’ Tumor Study
By Paul E. Andrews,
Panayotis
P. Kelalis, and Gerald M. Haase
Rochester, Minnesota and Denver, Colorado 0 Extrarenal Wilms’ tumor is extremely rare and occurs predominantly in children. Eight cases of extrarenal Wilms’ tumor were reported to the National Wilms’ Tumor Study from 1980 to 1986. Patients were followed in the study and not randomized to a particular treatment protocol. Seven patients had a favorable histology. One tumor located in the sacrococcygeal region showed immature teratoma with nephroblastic tissue. The embryogenesis of extrarenal Wilms’ tumor is controversial; however, tumor containing teratomatous elements most likely represents a different embryologic origin and, therefore, should be classified separately. All eight patients were treated with operative excision and chemotherapy. Seven of the eight patients were disease-free with a mean follow-up of 34.3 months. It can be inferred from this small group of patients that the prognosis is comparable to intrarenal Wilms’ tumor in the National Wilms’ Tumor Study. Copyright cj 1992 by W.B. Saunders Company INDEX WORDS: Wilms’tumor,
extrarenal.
LMS’ TUMOR is the most common malignancy of the genitourinary tract in children.’ VV The development of Wilms’ tumor outside the renal parenchymia is uncommon.2 A diagnosis of extrarenal Wilms’ by definition excludes a primary tumor in the kidney. Isolated cases of extrarenal Wilms’ tumor have been reported.3-44 There are less than 50 welldocumented cases of extrarenal Wilms’ tumor in the literature. This report will examine eight cases of extrarenal Wilms’ tumor reported to the National Wilms’ Tumor Study (NWTS) from 1980 to 1986. MATERIALS
AND METHODS
From 1980 to 1986, eight patients with extrarenal nephroblastoma were reported to the NWTS. These cases were reported independently by various institutions and do not necessarily represent all cases encountered. None of the cases had been previously reported. These patients were followed in the study and not randomized to a particular treatment protocol. Surgical and pathological check lists, along with records of follow-up, were completed on all patients except one. The check sheets were reviewed obtaining information regarding age of patient, sex, presenting symptoms, location of tumor. status of each kidney, operative procedure, adjuvant therapy, histology, presence of teratomatous elements, and follow-up. The treatment of these cases was not uniform because they were not randomized to a particular treatment protocol.
RESULTS
There were three boys and five girls. The ages at diagnosis ranged from 1 week to 4.3 years of age. The clinical presentation was nonspecific and depended JournalofPediatric Surgery, Vol 27, No 9 (September), 1992: pp 1181-l 184
on the location of the tumor. As reported in the literature, extrarenal Wilms’ tumor can occur in a variety of locations. Of the eight cases, two occurred in the sacrococcygeal region, two adjacent to the left kidney, one adjacent to the right kidney, one in a lumbar lipoma, one in the pelvis, and one the location was not well documented (Table 1). Three of these tumors were adjacent to a normal kidney separated by a capsule. In all the cases reviewed, except one, it was well documented that both kidneys were normal radiographically and at the time of surgery. All eight patients were treated with operative excision and chemotherapy (Table 2). One patient with juxtarenal Wilms’ tumor underwent nephrectomy and another underwent partial nephrectomy, both of the renal specimens were thoroughly examined and only showed normal renal parechyma with no evidence of nephroblastomatoses. Chemotherapy consisted of actinomytin and vincristine for 3 to 6 months for six of the eight patients. Two patients received adriamycin for metastatic disease, and one of these also received methotrexate. Two patients were treated with radiation therapy because of regionally advanced disease. Seven of the tumors had a favorable histology and in one case the histology was not well documented. In addition, seven of the cases were thoroughly examined for teratomatous elements. One of the tumors located in the sacrococcygeal region showed immature teratoma with elements of nephroblastoma. Seven of the eight patients were disease-free with a mean follow-up of 34.3 months. Follow-up ranged from 7 months to 74 months. One patient developed pulmonary metastasis at 6 months. However, with salvage chemotherapy, the patient was disease free at 48 months. Another patient who presented initially with regionally advanced disease, died at 24 months secondary to pulmonary metastasis. Currently, there is no accepted staging for extra-
From the Department of Urology Mayo Clinic and Mayo Foundation, Rochester. MN, and the Depattment of Pediattic SuQetyerv. Children i Hospital, Denver, CO. Date accepted: August 15, 1991. Supported in part by US Public Health Service Grant CA 42326 and the Mayo Foundation. Address reprint requests to P.P. Kelalis. MD, Department of Urology, Mayo Clinic, Rochester, MN 55905 Copyright o 1992 by W B. Saunders Company 0022-346819212709-0003$03.00l0 1181
ANDREWS,
1182
Table 1. tocation of Extrarenal Wilms’ Tumor
KELALIS, AND HAASE
Table 3. Pathological Staging
Sacrococcyeal
Stage
I
Adjacent to left kidney
Tumor contained within capsule; complete excision
Adjacent to right kidney
Tumor capsular surface intact; no residual tumor apparent beyond margins of resection
Lumbar lipoma
Stage II
Pelvis
Tumor extends beyond capsule but is completely excised
Unknown
Regional extension of tumor; tumor biopsied or local spillage of tumor, no residual tumor apparent at or beyond margin of exci-
renal Wilms’ tumor. However, the staging of the NWTS has been applied to these cases (Table 3). Staging of regional disease was based on an intact capsular surface of the tumor, just as is done with the capsular surface of the kidney with intrarenal Wilms’ tumor. Lymph node involvement, operative spillage, and distant metastasis was staged as for intrarenal Wilms’ tumor. One patient presented with stage I disease, four with stage II disease, one patient with stage III disease, and one with stage IV disease. DISCUSSION
Wilms’ tumor originating outside the kidney is extremely rare. This entity is poorly known and has generally only been reported as isolated cases. A diagnosis of extrarenal Wilms’ tumor must exclude a primary tumor in the kidney. It is important to rule out a primary intrarenal tumor with a secondary extrarenal metastases. In addition, in the case of a “juxtarenal” Wilms’ tumor, a supernumerary kidney must be ruled out. In the eight cases reviewed, a primary intrarenal tumor or a supernumerary kidney was excluded both radiographically and at the time of surgery. Extrarenal Wilms’ tumor has been reported to occur in a variety of locations. Clinical presentation is nonspecific and dependent on location of the tumor. Reported locations include inguinal region, endocervix, uterus, epididymis, ovotestis, and any place along the retroperitoneum.2-44 The location of the tumors presented in these eight patients is similar to other reported cases in the literature. The location of these tumors and others is impartant in understanding the controversy regarding histogenesis. It is generally accepted that intrarenal Wilms’ tumor arises
sion Stage Ill Residual tumor; lymph node involvement, peritoneal contamination by tumor spillage or peritoneal implants; tumor not completely removable because of local infiltration into vital structures
from metanephric blastema.2 The origin of extrarenal Wilms’ tumor is much more controversial. Location and pathology of reported cases in the literature have been used to support various theories of embryogenesis. Many believe that the origin of extrarenal Wilms’ parallels that of intrarenal Wilms’ tumor and arises from heterotopic metanephric blastema.2,4,8J7,2**24,32 Currently there is no report in the literature that documents the presence of extrarenal metanephric blastema in the retroperitneum of the fetus. There are others who believe that the presence of persistent mesonephric duct remnants in the walls of the cervix, vagina, and inguinal region in conjunction with reports of extrarenal Wilms’ tumor in these locations supports the theory of the mesonephros as the origin.5,8J5,22,25.30,32,45 However, it has been pointed out that the embryologic features of the mesonephros and metanephros overlap and that extrarenal Wilms’ tumor may arise from either the mesonephros or metanephros (intermediate and caudal segments of the nephrogenic cord). 22,45Another possible mechanism involves Connheims’ cell rest theory in which cells with persistent embryonal potential undergo malignant transformation.4s Debate exists as to whether a Wilms’ tumor surrounding a normal kidney separated by a capsule is truly an extrarenal nephroblastoma or an extrusion of metanephric blast-
Table 2. Clinical Data, Histology, Staging, Treatment,
and Follow-up
NW-E
Case Site
Histology
Teratomatous
stage
Follow-Up
Therapy
NO.
Sex
1
F
Sacrococcygeal
Favorable
No
II
Excision and chemotherapy
2
M
Adjacent to right kidney
Favorable
No
II
Excision (nephrectomy) and chemotherapy
3
F
Lumbar lipoma
Favorable
No
II
Excision and chemotherapy
4
M
Adjacent to left kidney
Favorable
No
IV
Excision, chemotherapy,
radiation
24 mo
5
F
Sacrococcygeal
Favorable
Yes
Ill
Excision, chemotherapy,
radiation
46 mo NED
6
F
Adjacent to right kidney
Favorable
No
I
Excision and chemotherapy
33 mo NED
7
M
Unknown
Excision and chemotherapy
26 mo NED
8
F
Pelvis
Favorable
No
Abbreviations: NED, no evidence of disease; pulm, pulmonary metastasis.
II
Excision and chemotherapy
16 mo NED 7 mo NED 74 mo NED
7 mo pulm
EXTRARENAL
1183
WILMS’ TUMOR
ema.45-48 Many authors argue that this group of tumors is not a true extrarenal Wilms’ tumor and should be listed separately as juxtarenal. In addition, when presented with juxtarenal Wilms’ tumor, a supernumerary kidney must be ruled out.1°J3 The cases of juxtarenal or pararenal Wilms’ tumor support the theory of an extrusion of subcapsular metanephric blastema.2,49 However, data regarding the presence or absence of residual foci in the adjacent kidney have not been documented in the past. In three of the cases in this series, the tumor surrounded the normal kidney separated by a capsule. In two of these three cases, a partial nephrectomy or a nephrectomy was performed. An examination of the pathological specimen showed no evidence of nephroblastomatosis in the removed renal unit. If elements of nephroblastomatosis had been found in the normal renal parechyma, this would have supported the theory of an extrusion of subcapsular metanephric blastema in the case of juxtarenal Wilms’ tumor. In the past, many of the reported cases arose within teratomas. In many of the other cases reported, it was not well documented as to whether teratomatous elements were present. In this series of eight patients, seven of the cases were thoroughly examined for teratomatous elements and one of the tumors located in the sacrococcygeal region showed immature teratoma with nephroblastic tissue. Teratomas containing nephroblastic tissue most likely represent a different embryologic origin and, therefore, should be classified separately. When extrarenal nephroblastic tissue is encountered, the pathologic specimen should be thoroughly examined for teratomatous elements with
thorough histologic examination mor 8.13.15
of the whole tu-
The treatment of these tumors was heterogeneous because they were not randomized to particular treatment protocol and were treated at various institutions. All eight patients were treated with operative excision and chemotherapy similar to the NWTS. Currently, there is no accepted staging for these tumors. However, the staging of the NWTS can easily be applied. Two patients presented with metastatic disease and the remainder presented with regionally localized disease. Seven of eight patients were disease free with a mean follow-up of 34.3 months. Caution must be exercised in interpreting survival data because of the small number of patients. However, it can be inferred that the prognosis with extrarenal Wilms’ tumor is comparable to the prognosis of intrarenal Wilms’ tumor in the NWTS. In summary, the diagnosis of extrarenal Wilms’ tumor by definition excluded the presence of a primary tumor in the kidney. A supernumerary kidney must be ruled out in the case of a juxtarenal Wilms’ tumor. The specimen must be thoroughly sectioned and examined for presence of teratomatous elements. Prognosis is similar to intrarenal Wilms’ tumor in the few cases presented as well as in the literature. Embryogenesis is controversal; however, the development to extrarenal Wilms’ tumor is most likely similar to that of intrarenal Wilms’ tumor and arises from heterotopic metanephric blastema. Future cases should be centralized with staging and treatment protocol similar to patients treated in the NWTS.
REFERENCES 1. Young JL, Miller RW: Incidence children J Pediatr 86:254-258, 1975
of malignant
tumours
in US
9. Willis RA: Pathology of Tumours Butterworths, 1967, pp 944-951
(ed 4). London,
2. Bennington JL. Beckwith JB: Tumors of the kidney, renal pelvis and ureter, In Atlas of Tumor Pathology. Washington, DC, Armed Forces Institute of Pathology, 2nd series, 1975, Fast. 12, pp 31-59
10. Wu JP, Garcia J: Supernumerary Wiscon Med J 70:211-216,197l
kidney with Wilms’ tumor.
3. Moyson FR, Maurus-Desmore ZR, Gape1 C: Tumour de Wilms’ mediastinale? Acta Chir Be1 60:118-128, 1961 (suppl 1)
12. Tebbi K, Ragub AH. Ternberg JL, et al: An extrarenal Wilms’ tumor arising from a sacrococcygeal teratoma. Clin Pediatr 13:1019-1021,1974
4. Fruhhng L, Blum E. Le Gal Y: A propos de trois cas de tumeurs ovarienn es dysgenttiques primitives a caracteres metanephrogenes. J Ural (Paris) 60:201-207, 1954 5. Tourdoire A, Weveux YJ: Deux cas de nephroblastomaedela loge rorale chez nadilte. J Urol (Paris) 66:448-450, 1960 6. Bhajekar AB. Joseph toma. Br J Urol36:187-190,
M. Bhat HS: Unattached 1964
7. Edelstein G, Webb RS. Ramsdahl Wilms’ tumor. Am J Surg 109:509-512,1965
MM,
nephroblas-
et al: Extrarenal
8. Malik TK. Malik GB, Biesch G: Retroperitoneal teratoma with nephroblastic tissue as the main component. Int Surg 47:246249.1967
England,
11. Thompson MR, Emmanuel IG, Campbell MS. et al: Extrarenal Wilms’ tumors. J Pediatr Surg 837-41, 1973
13. Ward SP, Dehner LP: Sacrococcygeal teratoma with nephroblastoma: A variant of extragonadal teratoma in childhood. Cancer 33:1355-1313.1974 14. Carmcy retroperitoneal
JA: Wilms’ tumor and renal teratoma. Cancer 35:1179-1183.
15. Akhtar M, Kott E, Brook Cancer 40:3087-3091.1977
B: Extrarenal
cell carcinoma 1975 Wilms’
in
tumor.
16. Gaikwad KD, Patil PS, Bhavthavkar AC. et al: Extrarenal Wilms’ tumor. Indian Pediatr 14:657-659, 1977 17. Atermon K, Grantmye E, Gillis DA: Extrarenal Wilms’ tumor: A review and case report. Invest Cell Pathol2:309-318, 1979
1184
18. Posalaky 2, Drake RM, Mowk JR, et al: Ectopic immature renal tissue over the dorsum of lumbar and sacral area in two infants. Pediatrics 69:336-339,1982 19. Harm D, Lohr J: Inguinaler Wilms tumor. Khn Paediatr 19054-56, 1978 20. McCauley RGK, Safaii H, Crowley CA, et al: Extrarenal Wilms’ tumor. Am J Dis Child 133: 1174-l 177, 1979 21. Kovnitsky MA, Zinovoy VE: Extrarenal variant of embryonal nephroma. Arch Pathol42:58-60,198O 22. Orlowski JP, Levin HS, Dyment PG: Intrascrotal Wilms’ tumor developing in a hetrotopic renal anlase of probable mesonephric origin. J Pediatr Surg 15:679-682, 1980 23. Taylor WF, Myers M, Taylor WR: Extrarenal Wilms’ tumor in an infant exposed to intrauterine phenytoin. Lancet 2:481-482. 1980 24. Bittercourt AL, Britto JF. Tonseca LE: Wilms’ tumor of the uterus: The first report of the literature. Cancer 47:2496-2499,198l 25. Ho J, Ma L, Wong RC: An extrarenal Wilms tumor arising from an undescended testis. Pathology 13:619-624.1981 26. Tang CK, Toker C, Wybel RG, et al: An unusual pelvic tumor with benign glandular sarcomatous and Wilms’ tumor in the compents. Hum Path01 12:940-944, 1981 27. Kawano N, Morii S, Yuda K, et al: Contiguous malignant astrocytoma and Wilms’like tumor in the brain. Cancer 49:25052512,1982 28. Tamaro P, Ford E, Valente M, et al: Un nuovo coso d’tumour di Wilms’ extrarenale. Pediatr Med Chir 4:143-148, 1982 29. Luchtrath H, DeLeon F, Giesen H, et al: Inguinal nephroblastoma. Virchause Arch (A) 405:113-118, 1984 30. Shimao S, Suzuki Y, Okada T: A case of bilateral Wilms’ tumor of the kidneys and retrourethral region. Eur J Pediatr 143:158-160, 1984 31. Todd DW, Roskos R, Baldwin J: Extrarenal Wilms’ tumor. Minn Med 67:635-638,1984 32. Bell DA, Shimm DS, Gung DL: Wilms’ tumor of the endocervix. Arch Pathol Lab Med 109:371-373,1985 33. Heyrs CF. Von Niekenk DST, Rossouw DJ, et al: Nephroblastoma in an ovotestis of a true hermaphrodite: A case report. J Urol 137:1003-1005.1987
ANDREWS, KELALIS, AND HAASE
34. Narasimhanao KL, Marwgha RK, Kaushik S, et al: Extrarenal Wilms’ tumor. J Pediatr Surg 24:212-214, 1989 35. Wakely PE, Sprague RI, Kornstein MY: Extrarenal Wilms’ tumor: An analysis of four cases. Hum Pathol20:691-695,1989 36. Lai H-S, Huns WT, How S-W Extrarenal Wilms’ tumor: A case report. J Pediatr Surg 23:454-456,1988 37. Adam YG, Rosin A, Oland J: Extrarenal Wilms’ tumor. J Surg Oncol22:56-58, 1983 38. Madanat F, Osbourne B, Cangir A: Extrarenal Wilms tumor. J Pediatr 93:439-443,1978 39. Kovetz MJ, Wong S, Klein FA: Extrarenal adult Wilms’ tumor. Cancer 60:2484-2488,1987 40. Sahin A, Berda JA: Primary ovarian Wilms’ tumor. Cancer 61:1460-1463,1988 41. Fu Ku, Tomi Y, Shibuya C, et al: Extrarenal Wilms’ tumor in the adult patient. A case report and review of the world literature. Am J Clin Pathol90:618-622, 1988 42. Johnson F, Lutten C, Limbert D: Extrarenal and urothelial Wilms’ tumor. Urology 15:370-373,198O 43. Wakely PE, Sprague RI, Kounstern MJ: Extrarenal Wilms’ tumor: An analysis of four cases. Hum Pathology 20:691-695, 1989 44. Strand WR, Chou P, Pero JE, et al: Extrarenal Wilms’ tumor occurring in the inguinal canal. J Urol 143:783-785, 1990 45. Aterman K: Extrarenal nephroblastomas. J Cancer Res Clin Oncol 115:409-417, 1989 46. Bodion M, Rigby CC: The pathology of nephroblastoma, In Riches E (ed): Tumors of the Kidney and Ureter, Monographs on Neoplastic Disease, vol 5. Edinburgh, Scotland. Livingstone, 1964. pp 219-233 47. Beckwith JB: Wilms’ tumor and other renal tumors of childhood: A selective review from the National Wilms’ Tumor Study Pathology Center. Hum Pathol14:481-492,1983 48. Beckwith JB: Wilms’ tumor and other renal tumors of childhood: An update. J Ural 136:320-324, 1986 49. Bove KE, McAdams AJ: The nephroblastomatosis complex and its relationships to Wilms’ tumor: A clinicopathologic treatise. Perspect Pediatr Pathol3:185-223,1976
Extrarenal Wilms’ Tumor: of the National Wilms’ Tumor Study
By Paul E. Andrews,
Panayotis
P. Kelalis, and Gerald M. Haase
Rochester, Minnesota and Denver, Colorado 0 Extrarenal Wilms’ tumor is extremely rare and occurs predominantly in children. Eight cases of extrarenal Wilms’ tumor were reported to the National Wilms’ Tumor Study from 1980 to 1986. Patients were followed in the study and not randomized to a particular treatment protocol. Seven patients had a favorable histology. One tumor located in the sacrococcygeal region showed immature teratoma with nephroblastic tissue. The embryogenesis of extrarenal Wilms’ tumor is controversial; however, tumor containing teratomatous elements most likely represents a different embryologic origin and, therefore, should be classified separately. All eight patients were treated with operative excision and chemotherapy. Seven of the eight patients were disease-free with a mean follow-up of 34.3 months. It can be inferred from this small group of patients that the prognosis is comparable to intrarenal Wilms’ tumor in the National Wilms’ Tumor Study. Copyright cj 1992 by W.B. Saunders Company INDEX WORDS: Wilms’tumor,
extrarenal.
LMS’ TUMOR is the most common malignancy of the genitourinary tract in children.’ VV The development of Wilms’ tumor outside the renal parenchymia is uncommon.2 A diagnosis of extrarenal Wilms’ by definition excludes a primary tumor in the kidney. Isolated cases of extrarenal Wilms’ tumor have been reported.3-44 There are less than 50 welldocumented cases of extrarenal Wilms’ tumor in the literature. This report will examine eight cases of extrarenal Wilms’ tumor reported to the National Wilms’ Tumor Study (NWTS) from 1980 to 1986. MATERIALS
AND METHODS
From 1980 to 1986, eight patients with extrarenal nephroblastoma were reported to the NWTS. These cases were reported independently by various institutions and do not necessarily represent all cases encountered. None of the cases had been previously reported. These patients were followed in the study and not randomized to a particular treatment protocol. Surgical and pathological check lists, along with records of follow-up, were completed on all patients except one. The check sheets were reviewed obtaining information regarding age of patient, sex, presenting symptoms, location of tumor. status of each kidney, operative procedure, adjuvant therapy, histology, presence of teratomatous elements, and follow-up. The treatment of these cases was not uniform because they were not randomized to a particular treatment protocol.
RESULTS
There were three boys and five girls. The ages at diagnosis ranged from 1 week to 4.3 years of age. The clinical presentation was nonspecific and depended JournalofPediatric Surgery, Vol 27, No 9 (September), 1992: pp 1181-l 184
on the location of the tumor. As reported in the literature, extrarenal Wilms’ tumor can occur in a variety of locations. Of the eight cases, two occurred in the sacrococcygeal region, two adjacent to the left kidney, one adjacent to the right kidney, one in a lumbar lipoma, one in the pelvis, and one the location was not well documented (Table 1). Three of these tumors were adjacent to a normal kidney separated by a capsule. In all the cases reviewed, except one, it was well documented that both kidneys were normal radiographically and at the time of surgery. All eight patients were treated with operative excision and chemotherapy (Table 2). One patient with juxtarenal Wilms’ tumor underwent nephrectomy and another underwent partial nephrectomy, both of the renal specimens were thoroughly examined and only showed normal renal parechyma with no evidence of nephroblastomatoses. Chemotherapy consisted of actinomytin and vincristine for 3 to 6 months for six of the eight patients. Two patients received adriamycin for metastatic disease, and one of these also received methotrexate. Two patients were treated with radiation therapy because of regionally advanced disease. Seven of the tumors had a favorable histology and in one case the histology was not well documented. In addition, seven of the cases were thoroughly examined for teratomatous elements. One of the tumors located in the sacrococcygeal region showed immature teratoma with elements of nephroblastoma. Seven of the eight patients were disease-free with a mean follow-up of 34.3 months. Follow-up ranged from 7 months to 74 months. One patient developed pulmonary metastasis at 6 months. However, with salvage chemotherapy, the patient was disease free at 48 months. Another patient who presented initially with regionally advanced disease, died at 24 months secondary to pulmonary metastasis. Currently, there is no accepted staging for extra-
From the Department of Urology Mayo Clinic and Mayo Foundation, Rochester. MN, and the Depattment of Pediattic SuQetyerv. Children i Hospital, Denver, CO. Date accepted: August 15, 1991. Supported in part by US Public Health Service Grant CA 42326 and the Mayo Foundation. Address reprint requests to P.P. Kelalis. MD, Department of Urology, Mayo Clinic, Rochester, MN 55905 Copyright o 1992 by W B. Saunders Company 0022-346819212709-0003$03.00l0 1181
ANDREWS,
1182
Table 1. tocation of Extrarenal Wilms’ Tumor
KELALIS, AND HAASE
Table 3. Pathological Staging
Sacrococcyeal
Stage
I
Adjacent to left kidney
Tumor contained within capsule; complete excision
Adjacent to right kidney
Tumor capsular surface intact; no residual tumor apparent beyond margins of resection
Lumbar lipoma
Stage II
Pelvis
Tumor extends beyond capsule but is completely excised
Unknown
Regional extension of tumor; tumor biopsied or local spillage of tumor, no residual tumor apparent at or beyond margin of exci-
renal Wilms’ tumor. However, the staging of the NWTS has been applied to these cases (Table 3). Staging of regional disease was based on an intact capsular surface of the tumor, just as is done with the capsular surface of the kidney with intrarenal Wilms’ tumor. Lymph node involvement, operative spillage, and distant metastasis was staged as for intrarenal Wilms’ tumor. One patient presented with stage I disease, four with stage II disease, one patient with stage III disease, and one with stage IV disease. DISCUSSION
Wilms’ tumor originating outside the kidney is extremely rare. This entity is poorly known and has generally only been reported as isolated cases. A diagnosis of extrarenal Wilms’ tumor must exclude a primary tumor in the kidney. It is important to rule out a primary intrarenal tumor with a secondary extrarenal metastases. In addition, in the case of a “juxtarenal” Wilms’ tumor, a supernumerary kidney must be ruled out. In the eight cases reviewed, a primary intrarenal tumor or a supernumerary kidney was excluded both radiographically and at the time of surgery. Extrarenal Wilms’ tumor has been reported to occur in a variety of locations. Clinical presentation is nonspecific and dependent on location of the tumor. Reported locations include inguinal region, endocervix, uterus, epididymis, ovotestis, and any place along the retroperitoneum.2-44 The location of the tumors presented in these eight patients is similar to other reported cases in the literature. The location of these tumors and others is impartant in understanding the controversy regarding histogenesis. It is generally accepted that intrarenal Wilms’ tumor arises
sion Stage Ill Residual tumor; lymph node involvement, peritoneal contamination by tumor spillage or peritoneal implants; tumor not completely removable because of local infiltration into vital structures
from metanephric blastema.2 The origin of extrarenal Wilms’ tumor is much more controversial. Location and pathology of reported cases in the literature have been used to support various theories of embryogenesis. Many believe that the origin of extrarenal Wilms’ parallels that of intrarenal Wilms’ tumor and arises from heterotopic metanephric blastema.2,4,8J7,2**24,32 Currently there is no report in the literature that documents the presence of extrarenal metanephric blastema in the retroperitneum of the fetus. There are others who believe that the presence of persistent mesonephric duct remnants in the walls of the cervix, vagina, and inguinal region in conjunction with reports of extrarenal Wilms’ tumor in these locations supports the theory of the mesonephros as the origin.5,8J5,22,25.30,32,45 However, it has been pointed out that the embryologic features of the mesonephros and metanephros overlap and that extrarenal Wilms’ tumor may arise from either the mesonephros or metanephros (intermediate and caudal segments of the nephrogenic cord). 22,45Another possible mechanism involves Connheims’ cell rest theory in which cells with persistent embryonal potential undergo malignant transformation.4s Debate exists as to whether a Wilms’ tumor surrounding a normal kidney separated by a capsule is truly an extrarenal nephroblastoma or an extrusion of metanephric blast-
Table 2. Clinical Data, Histology, Staging, Treatment,
and Follow-up
NW-E
Case Site
Histology
Teratomatous
stage
Follow-Up
Therapy
NO.
Sex
1
F
Sacrococcygeal
Favorable
No
II
Excision and chemotherapy
2
M
Adjacent to right kidney
Favorable
No
II
Excision (nephrectomy) and chemotherapy
3
F
Lumbar lipoma
Favorable
No
II
Excision and chemotherapy
4
M
Adjacent to left kidney
Favorable
No
IV
Excision, chemotherapy,
radiation
24 mo
5
F
Sacrococcygeal
Favorable
Yes
Ill
Excision, chemotherapy,
radiation
46 mo NED
6
F
Adjacent to right kidney
Favorable
No
I
Excision and chemotherapy
33 mo NED
7
M
Unknown
Excision and chemotherapy
26 mo NED
8
F
Pelvis
Favorable
No
Abbreviations: NED, no evidence of disease; pulm, pulmonary metastasis.
II
Excision and chemotherapy
16 mo NED 7 mo NED 74 mo NED
7 mo pulm
EXTRARENAL
1183
WILMS’ TUMOR
ema.45-48 Many authors argue that this group of tumors is not a true extrarenal Wilms’ tumor and should be listed separately as juxtarenal. In addition, when presented with juxtarenal Wilms’ tumor, a supernumerary kidney must be ruled out.1°J3 The cases of juxtarenal or pararenal Wilms’ tumor support the theory of an extrusion of subcapsular metanephric blastema.2,49 However, data regarding the presence or absence of residual foci in the adjacent kidney have not been documented in the past. In three of the cases in this series, the tumor surrounded the normal kidney separated by a capsule. In two of these three cases, a partial nephrectomy or a nephrectomy was performed. An examination of the pathological specimen showed no evidence of nephroblastomatosis in the removed renal unit. If elements of nephroblastomatosis had been found in the normal renal parechyma, this would have supported the theory of an extrusion of subcapsular metanephric blastema in the case of juxtarenal Wilms’ tumor. In the past, many of the reported cases arose within teratomas. In many of the other cases reported, it was not well documented as to whether teratomatous elements were present. In this series of eight patients, seven of the cases were thoroughly examined for teratomatous elements and one of the tumors located in the sacrococcygeal region showed immature teratoma with nephroblastic tissue. Teratomas containing nephroblastic tissue most likely represent a different embryologic origin and, therefore, should be classified separately. When extrarenal nephroblastic tissue is encountered, the pathologic specimen should be thoroughly examined for teratomatous elements with
thorough histologic examination mor 8.13.15
of the whole tu-
The treatment of these tumors was heterogeneous because they were not randomized to particular treatment protocol and were treated at various institutions. All eight patients were treated with operative excision and chemotherapy similar to the NWTS. Currently, there is no accepted staging for these tumors. However, the staging of the NWTS can easily be applied. Two patients presented with metastatic disease and the remainder presented with regionally localized disease. Seven of eight patients were disease free with a mean follow-up of 34.3 months. Caution must be exercised in interpreting survival data because of the small number of patients. However, it can be inferred that the prognosis with extrarenal Wilms’ tumor is comparable to the prognosis of intrarenal Wilms’ tumor in the NWTS. In summary, the diagnosis of extrarenal Wilms’ tumor by definition excluded the presence of a primary tumor in the kidney. A supernumerary kidney must be ruled out in the case of a juxtarenal Wilms’ tumor. The specimen must be thoroughly sectioned and examined for presence of teratomatous elements. Prognosis is similar to intrarenal Wilms’ tumor in the few cases presented as well as in the literature. Embryogenesis is controversal; however, the development to extrarenal Wilms’ tumor is most likely similar to that of intrarenal Wilms’ tumor and arises from heterotopic metanephric blastema. Future cases should be centralized with staging and treatment protocol similar to patients treated in the NWTS.
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