0022-5347 /90/1434-0183$02.00/0 THE JOURNAL OF UROLOGY
Copyright© 1990 by
Vol. 143) Printed in
AMERICAN lJRCLOGiCAL ASSOCIATION, !NC.
EXTRARENAL WILMS TUMOR OCCURRING IN THE INGUINAL CANAL WILLIAM R STRAND,* PAULINE CHOU, JAMES E. PERO
AND
WILLIAM E. KAPLAN
From the Departments of Urology and Pathology, Children's Memorial Hospital, Chicago, Illinois
ABSTRACT
We report an unusual case of extrarenal Wilms tumor discovered incidentally during routine inguinal orchiopexy. The world literature and embryological implications of Wilms tumor in the inguinal canal are reviewed. (J. Ural., 143: 783-785, 1990) Extrarenal Wilms tumor is a rare entity that occurs most commonly in the retroperitoneum of young children.' Discovery of an extrarenal Wilms tumor in the inguinal canal is more unusual and poses some intriguing questions regarding the embryogenesis of these tumors. We report case 10 in the literature of extrarenal Wilms tumor in the inguinal canal, and review the treatment and prognosis. CASE REPORT
An 11-month-old white boy had a nonpalable undescended right testicle since birth. During right inguinal exploration a firm 2 cm. nodular density contiguous with the right inguinal hernia sac was dissected from the pubic tubercle. Small blood vessels supplying the density passed medially through the internal inguinal ring with the hernia sac. The testis was at the internal inguinal ring. The mass was resected completely and the inguinal orchiopexy was completed without further incident. Pathological correlation indicated that the nodular density contained epithelial, stromal and blastematous elements characteristic of Wilms tumor with favorable histological findings. Microscopic surgical margins were negative for tumor. A chest x-ray, and computerized tomography of the chest, abdomen and pelvis revealed no other abnormalities. Specifically, 2 normal kidneys were identified. Family history was negative for renal or neoplastic disorders. The patient was registered with the National Wilms Tumor Study-4, and began 6 months of treatment with actinomycin D and vincristine. Pathological findings. The specimen had a roughly spherical configuration with a pinkish-tan, variegated appearance on cut section. Microscopically, the multilobulated tumor demonstrated a triphasic pattern composed of compact nests of small hyperchromatic blastemal cells with scant cytoplasm associated with areas of tubular differentiation (part A of figure) separated broad, dense fibrous bands. Cystic formation as well as numerous glomeruloid structures were identified. In some areas the tumor assumed a papillary intracystic growth pattern with scattered psamrnoma bodies (part B of figure). Neither cellular anaplasia nor teratomatous differentiation was identified. DISCUSSION
Incidental discovery of an extrarenal Wilms tumor in the inguinal canal has not been reported previously. However, an inguinal location has been reported in 9 prior cases (see table ), 2- 10 each presenting as a palpable mass and demonstrating favorable histological findings. Also, a minute focus of Wilms tumor was detected in the scrotal ovotestis of a true hermaphrodite. 11 Optimal postoperative treatment included resection followed by vincristine and actinomycin D-based chemotherapy. 3 • 6 • 8 Disease recurred in all 3 patients treated initially with only local resection of tumor. 2 • 7 • 10 Subsequent Accepted for publication October 13, 1989. * Requests for reprints: Department of Urology, Naval Hospital Oakland, Oakland, California 94627. 783
radiotherapy 2 or chemotherapy 7 • 10 provided effective tumor control with no evidence of disease progression 8 to 24 months after therapy. The only death occurred in a 3-year-old boy who had refractory recurrent tumor 6 months after incomplete local resection of tumor, inguinal radiotherapy and a course of actinomycin D chemotherapy. Despite further chemotherapy with vincristine and cyclophosphamide, tumor persisted infiltrating the spermatic cord at the site of the original tumor and massive metastases were present in the right lung at postmortem examination. 2 The etiology of extrarenal Wilms tumor not associated with teratoma remains unclear. 3 • 4 The majority occur within the retroperitoneum adjacent to the kidney.' However, other locations have been reported, including the inguinal canal (9 cases), 2 - 10 chest wall 4 or mediastinum (2), 12 uterus (2), 13 testis (2) 11 · 14 and ovary (1). 15 These tumors are histologically indistinguishable from Wilms tumor in the kidney. 2 - 15 Therefore, a similar mechanism of origin is expected. Early theories of histogenesis of Wilms tumor sought to explain the presence of heterotopic tissues not normally found in the metanephros, 1 and suggested origin from primitive mesoderm, mesonephric tissue, totipotential blastomeres and neuroepithelial cells. Recognition that the nephrogenic tissues of the developing kidney could produce muscle, fat and other varieties of cells by metaplasia obviated the need to include aberrant embryonic tissues in the proposed theories of development. 16 Bennington and Beckwith noted that although an origin for Wilms tumor from metanephric cells possessing embryonal potentialities has achieved virtually unamimous acceptance, this explanation does not account for extrarenal Wilms tumors arising outside of the retroperitoneum. 1 Glomerular and tubular differentiation in and around extrarenal Wilms tumors indicates that they develop from nephrogenic tissue.rn To account for the diversity of reported locations, Thompson and associates ascribed their origin to primitive undifferentiated mesoderm. 2 McCauley and associates observed that these tumors could result equally from more differentiated mesonephric remnants, 17 which are capable of glomerular and tubular differentiation, 16 and may extend from the lower thoracic to the inguinal regions. 18 Although origin of extrarenal Wilms tumor from mesonephric tissue had long been suspected, 1 this theory had received little attention, since these tumors bear a greater histological resemblance to primitive metanephric blastema. 16 Orlowski and associates proposed that Wilms tumors may develop from either the mesonephros or metanephros. 7 They noted that although the product of the intermediate (mesonephric) and caudal (metanephric) segments of the nephrogenic cord is unique in normal development, the distinction between these segments may not be embryologically clear-cut. The relative frequency with which extrarenal Wilms tumors are discovered in the inguinal canal2- 10 as well as the characteristic presence of differentiated tubular elements adjacent to
784
STRAND AND ASSOCIATES
A, classical histological findings of Wilms tumor with blastema as well as epithelial (tubular) components present at inguinal location. H & E, reduced from X40. B, stromal fibrosis surrounding papillary or microcystic structures with occasional psammoma bodies. Inset shows laminated psammoma body. H & E, reduced from XlOO.
these tumors 2 • 3 · 5 · 7 • 8 • 10 implicates an origin from mesonephric tissue. Embryologically, the mesonephros is associated intimately with the processus vaginalis, gubernaculum and developing gonad. 18 The mesonephric duct becomes the vas deferens, the seminal vesicle and epididymis in the male subject, and Gartner's duct in the female subject. Although the mesonephric glomerular structures regress as the definitive kidney develops from the metanephros, 16• 18 remnants of a number of the caudal mesonephric tubules persist. 18 In the male subject they form the paradidymis and the efferent ductules of the epididymis,
whereas in the female subject they form the tubules of the paroophoron and epoophron. Aberrant mesonephric tubules, termed ductuli aberrantes superior and the ductulus aberrans inferior, also may be demonstrated histologically proximate to the gonad. 18 Extrarenal Wilms tumors encasing the testis 14 or ovary, 15 or adherent to the spermatic cord3 • 5 - 7 presumably develop from these mesonephric remnants. Tumors caudal to the testis and adherent to the pubic tubercle as in our case most probably derive from mesonephric remnants trapped in the developing gubernaculum as the urogenital ridge joins the inguinal fold. 18 This mechanism is supported further by the incidence of extrarenal Wilms tumor adherent to either the processus vaginalis 8- 10 or round ligament 2 in female patients. Polypoid Wilms tumor arising from the uterus or endocervix may be ascribed to remnant mesonephric tubules contiguous with Gartner's duct. 13 Extrarenal Wilms tumor in the inguinal canal presumably originates from cells possessing persistent embryonal potentialities (Connheim's cell rest theory), which undergo transformation to malignancy. 1 Orlowski and associates cited the 2mutational theory of Knudson and Strong, and proposed that the initial event occurs during embryonal development (when the mesonephros ordinarily progresses to full form and function) and results in an embryonic rest of renal blastema. 7 A second mutation leads to the development of Wilms tumor. de Chadarevian and associates reported histological evidence of such direct transformation of nodular renal blastema to Wilms tumor. 19 More recently, Saito and associates incidentally discovered a 1. 7 cm. nodule of benign immature renal tissue in the right inguinal canal of a 3-year-old boy undergoing routine orchiopexy. 20 Extrarenal Wilms tumor is a rare entity that must be considered when a solid mass is encountered in the inguinal canal. After complete local resection and appropriate combination chemotherapy, a good prognosis is expected. Wilms tumors arising at an inguinal location are indistinguishable histologically from Wilms tumors in the kidney. Adjacent tubular differentiation and the relative frequency with which these tumors are discovered in the inguinal canal support the theory that they originate from ectopic rests of mesonephric tissue. REFERENCES 1. Bennington, J. L. and Beckwith, J.B.: Tumors of the kidney, renal
pelvis and ureter. In: Atlas of Tumor Pathology. Washington, D. C.: Armed Forces Institute of Pathology, 2nd series, fasc. 12, pp. 31-59, 1975. 2. Thompson, M. R., Emmanuel, I. G., Campbell, M. S. and Zachary, R. B.: Extrarenal Wilms' tumors. J. Ped. Surg., 8: 37, 1973.
Extrarenal Wilms tumor in the inguinal canal
Reference Thompson and associates
2
Akhtar (1977) 3 and Madanat (1978) 4 and their associates (same pt.) Harms and L6hr 5 Taylor and associates 6 Orlowski and associates 7 Luchtrath and associates8 Okamura and associates 9 Lai and associates 10 Present case
Age-Sex
Side
3yrs.-M 4 yrs.-F 2mos.-M
Rt. Rt.
3yrs.-M 6mos.-M
Lt.
3yrs.-M 14 mos.-F 3 yrs.-F 5 yrs.-F 11 mos.-M
Initial Therapy
Results (mos.)
Actinomycin D/radiotherapy None Vincristine/actinomycin D
Recurrence* Recurrencet No evidence of recurrent disease (22) No evidence of recurrent disease (6)
Lt. Lt.
Vincristine/actinomycin D/radiotherapy None Vincristine/actinomycin D
Rt. Rt. Rt.
None Vincristine/actinomycin D
Lt.
Lt. Recurrencet No evidence of recurrent disease (34) Recurrence§
* Patient died. Local recurrence and metastatic spread to lungs and left renal hilus were noted at autopsy. t Local recurrence to right labia majora with no evidence of recurrent disease 24 months after local radiotherapy. t Pulmonary metastasis to left lower lobe (12 months later) with no evidence of recurrent disease 18 months after pulmonary radiotherapy and vincristine/actinomycin D. § Local recurrence to right inguinal region (11 months later) with no evidence of recurrent disease 8 months after actinomycin D.
EXTRARENAL WILMS TUMOR OCCURRING IN INGUINAL CANAL 3. Akhtar, M., Kott, E. and Brooks, B.: Extrarena! Wilms' tumor: report of a case and review of the literature. Cancer, 40: 3087, 1977. 4. Madanat, F., Osborne, B., Cangir, A. and Sutow, W.W.: Extrarenal Wilms' tumor. J. Ped., 93: 439, 1978. 5. Harms, D. and Lohr, J.: Inguinaler Wilms Tumor. Klin. Paed., 190: 54, 1978. 6. Taylor, W. F., Myers, M. and Taylor, W. R.: Extrarenal Wilms' tumour in an infant exposed to intrauterine phenytoin. Lancet, 2: 481, 1980. 7. Orlowski, J.P., Levin, H. S. and Dyment, P. G.: Intrascrotal Wilms' tumor developing in a heterotopic renal anlage of probable mesonephric origin. J. Ped. Surg., 15: 679, 1980. 8. Luchtrath, H., de Leon, F., Giesen, H. and Gok, Y.: Inguinal nephroblastoma. Virchows Arch. A, 405: 113, 1984. 9. Okamura, R., Tanaka, T. and Hagamaki, H.: A case of Wilms' tumor in the right inguinal region. Jap. J. Clin. Surg., 39: 419, 1984. 10. Lai, H. S., Hung, W. T. and How, S. W.: Extrarenal Wilms' tumor: a case report. J. Ped. Surg., 23: 454, 1988. 11. Heyns, C. F., Van Niekerk, D. J. T., Rossouw, D. J., Burger, E. C. and De Klerk, D. P.: Nephroblastoma in an ovotestis of a true hermaphrodite: a case report. J. Urol., 137: 1003, 1987.
785
12. tv'Ioyson, F. R., Maurus-Desmarez, R. and Gompel, C.: Tumeur de Wilms' mediastinale? Acta Chir. Belg., suppl. 2, p. 118, 1961. 13. Bell, D. A., Shimm, D. S. and Gang, D. L.: Wilms' tumor of the endocervix. Arch. Path. Lab. Med., 109: 371, 1985. 14. Ho, J., Ma, L. and Wong, K. C.: An extrarenal Wilms' tumour arising from an undescended testis. Pathology, 13: 619, 1981. 15. Sahin, A. and Benda, J. A.: Primary ovarian Wilms' tumor. Cancer, 61: 1460, 1988. 16. Potter, E. L.: Normal and Abnormal Development of the Kidney. Chicago: Year Book Medical Publishers, Inc., 1972. 17. McCauley, R. G. K., Safaii, H., Crowley, C. A. and Pinn, V. W.: Extrarenal Wilms' tumor. Amer. J. Dis. Child., 133: 1174, 1979. 18. Hamilton, W. J. and Mossman, H. W.: The urogenital system. In: Human Embryology: Prenatal Development of Form and Function, 4th ed. London: The MacMillan Press, Ltd., chapt. 12, pp. 377-436, 1978. 19. de Chadarevian, J. P., Fletcher, B. D., Chatten, J. and Rabinovitch, H. H.: Massive infantile nephroblastomatosis: a clinical, radiological, and pathological analysis of four cases. Cancer, 39: 2294, 1977. 20. Saito, S., Higa, I., Koyama, Y., Hatano, T., Hayakawa, M., Osawa, A. and Toda, T.: Immature renal tissue in inguinal canal. J. Urol., 142: 106, 1989.
Copyright© 1990 by
Vol. 143) Printed in
AMERICAN lJRCLOGiCAL ASSOCIATION, !NC.
EXTRARENAL WILMS TUMOR OCCURRING IN THE INGUINAL CANAL WILLIAM R STRAND,* PAULINE CHOU, JAMES E. PERO
AND
WILLIAM E. KAPLAN
From the Departments of Urology and Pathology, Children's Memorial Hospital, Chicago, Illinois
ABSTRACT
We report an unusual case of extrarenal Wilms tumor discovered incidentally during routine inguinal orchiopexy. The world literature and embryological implications of Wilms tumor in the inguinal canal are reviewed. (J. Ural., 143: 783-785, 1990) Extrarenal Wilms tumor is a rare entity that occurs most commonly in the retroperitoneum of young children.' Discovery of an extrarenal Wilms tumor in the inguinal canal is more unusual and poses some intriguing questions regarding the embryogenesis of these tumors. We report case 10 in the literature of extrarenal Wilms tumor in the inguinal canal, and review the treatment and prognosis. CASE REPORT
An 11-month-old white boy had a nonpalable undescended right testicle since birth. During right inguinal exploration a firm 2 cm. nodular density contiguous with the right inguinal hernia sac was dissected from the pubic tubercle. Small blood vessels supplying the density passed medially through the internal inguinal ring with the hernia sac. The testis was at the internal inguinal ring. The mass was resected completely and the inguinal orchiopexy was completed without further incident. Pathological correlation indicated that the nodular density contained epithelial, stromal and blastematous elements characteristic of Wilms tumor with favorable histological findings. Microscopic surgical margins were negative for tumor. A chest x-ray, and computerized tomography of the chest, abdomen and pelvis revealed no other abnormalities. Specifically, 2 normal kidneys were identified. Family history was negative for renal or neoplastic disorders. The patient was registered with the National Wilms Tumor Study-4, and began 6 months of treatment with actinomycin D and vincristine. Pathological findings. The specimen had a roughly spherical configuration with a pinkish-tan, variegated appearance on cut section. Microscopically, the multilobulated tumor demonstrated a triphasic pattern composed of compact nests of small hyperchromatic blastemal cells with scant cytoplasm associated with areas of tubular differentiation (part A of figure) separated broad, dense fibrous bands. Cystic formation as well as numerous glomeruloid structures were identified. In some areas the tumor assumed a papillary intracystic growth pattern with scattered psamrnoma bodies (part B of figure). Neither cellular anaplasia nor teratomatous differentiation was identified. DISCUSSION
Incidental discovery of an extrarenal Wilms tumor in the inguinal canal has not been reported previously. However, an inguinal location has been reported in 9 prior cases (see table ), 2- 10 each presenting as a palpable mass and demonstrating favorable histological findings. Also, a minute focus of Wilms tumor was detected in the scrotal ovotestis of a true hermaphrodite. 11 Optimal postoperative treatment included resection followed by vincristine and actinomycin D-based chemotherapy. 3 • 6 • 8 Disease recurred in all 3 patients treated initially with only local resection of tumor. 2 • 7 • 10 Subsequent Accepted for publication October 13, 1989. * Requests for reprints: Department of Urology, Naval Hospital Oakland, Oakland, California 94627. 783
radiotherapy 2 or chemotherapy 7 • 10 provided effective tumor control with no evidence of disease progression 8 to 24 months after therapy. The only death occurred in a 3-year-old boy who had refractory recurrent tumor 6 months after incomplete local resection of tumor, inguinal radiotherapy and a course of actinomycin D chemotherapy. Despite further chemotherapy with vincristine and cyclophosphamide, tumor persisted infiltrating the spermatic cord at the site of the original tumor and massive metastases were present in the right lung at postmortem examination. 2 The etiology of extrarenal Wilms tumor not associated with teratoma remains unclear. 3 • 4 The majority occur within the retroperitoneum adjacent to the kidney.' However, other locations have been reported, including the inguinal canal (9 cases), 2 - 10 chest wall 4 or mediastinum (2), 12 uterus (2), 13 testis (2) 11 · 14 and ovary (1). 15 These tumors are histologically indistinguishable from Wilms tumor in the kidney. 2 - 15 Therefore, a similar mechanism of origin is expected. Early theories of histogenesis of Wilms tumor sought to explain the presence of heterotopic tissues not normally found in the metanephros, 1 and suggested origin from primitive mesoderm, mesonephric tissue, totipotential blastomeres and neuroepithelial cells. Recognition that the nephrogenic tissues of the developing kidney could produce muscle, fat and other varieties of cells by metaplasia obviated the need to include aberrant embryonic tissues in the proposed theories of development. 16 Bennington and Beckwith noted that although an origin for Wilms tumor from metanephric cells possessing embryonal potentialities has achieved virtually unamimous acceptance, this explanation does not account for extrarenal Wilms tumors arising outside of the retroperitoneum. 1 Glomerular and tubular differentiation in and around extrarenal Wilms tumors indicates that they develop from nephrogenic tissue.rn To account for the diversity of reported locations, Thompson and associates ascribed their origin to primitive undifferentiated mesoderm. 2 McCauley and associates observed that these tumors could result equally from more differentiated mesonephric remnants, 17 which are capable of glomerular and tubular differentiation, 16 and may extend from the lower thoracic to the inguinal regions. 18 Although origin of extrarenal Wilms tumor from mesonephric tissue had long been suspected, 1 this theory had received little attention, since these tumors bear a greater histological resemblance to primitive metanephric blastema. 16 Orlowski and associates proposed that Wilms tumors may develop from either the mesonephros or metanephros. 7 They noted that although the product of the intermediate (mesonephric) and caudal (metanephric) segments of the nephrogenic cord is unique in normal development, the distinction between these segments may not be embryologically clear-cut. The relative frequency with which extrarenal Wilms tumors are discovered in the inguinal canal2- 10 as well as the characteristic presence of differentiated tubular elements adjacent to
784
STRAND AND ASSOCIATES
A, classical histological findings of Wilms tumor with blastema as well as epithelial (tubular) components present at inguinal location. H & E, reduced from X40. B, stromal fibrosis surrounding papillary or microcystic structures with occasional psammoma bodies. Inset shows laminated psammoma body. H & E, reduced from XlOO.
these tumors 2 • 3 · 5 · 7 • 8 • 10 implicates an origin from mesonephric tissue. Embryologically, the mesonephros is associated intimately with the processus vaginalis, gubernaculum and developing gonad. 18 The mesonephric duct becomes the vas deferens, the seminal vesicle and epididymis in the male subject, and Gartner's duct in the female subject. Although the mesonephric glomerular structures regress as the definitive kidney develops from the metanephros, 16• 18 remnants of a number of the caudal mesonephric tubules persist. 18 In the male subject they form the paradidymis and the efferent ductules of the epididymis,
whereas in the female subject they form the tubules of the paroophoron and epoophron. Aberrant mesonephric tubules, termed ductuli aberrantes superior and the ductulus aberrans inferior, also may be demonstrated histologically proximate to the gonad. 18 Extrarenal Wilms tumors encasing the testis 14 or ovary, 15 or adherent to the spermatic cord3 • 5 - 7 presumably develop from these mesonephric remnants. Tumors caudal to the testis and adherent to the pubic tubercle as in our case most probably derive from mesonephric remnants trapped in the developing gubernaculum as the urogenital ridge joins the inguinal fold. 18 This mechanism is supported further by the incidence of extrarenal Wilms tumor adherent to either the processus vaginalis 8- 10 or round ligament 2 in female patients. Polypoid Wilms tumor arising from the uterus or endocervix may be ascribed to remnant mesonephric tubules contiguous with Gartner's duct. 13 Extrarenal Wilms tumor in the inguinal canal presumably originates from cells possessing persistent embryonal potentialities (Connheim's cell rest theory), which undergo transformation to malignancy. 1 Orlowski and associates cited the 2mutational theory of Knudson and Strong, and proposed that the initial event occurs during embryonal development (when the mesonephros ordinarily progresses to full form and function) and results in an embryonic rest of renal blastema. 7 A second mutation leads to the development of Wilms tumor. de Chadarevian and associates reported histological evidence of such direct transformation of nodular renal blastema to Wilms tumor. 19 More recently, Saito and associates incidentally discovered a 1. 7 cm. nodule of benign immature renal tissue in the right inguinal canal of a 3-year-old boy undergoing routine orchiopexy. 20 Extrarenal Wilms tumor is a rare entity that must be considered when a solid mass is encountered in the inguinal canal. After complete local resection and appropriate combination chemotherapy, a good prognosis is expected. Wilms tumors arising at an inguinal location are indistinguishable histologically from Wilms tumors in the kidney. Adjacent tubular differentiation and the relative frequency with which these tumors are discovered in the inguinal canal support the theory that they originate from ectopic rests of mesonephric tissue. REFERENCES 1. Bennington, J. L. and Beckwith, J.B.: Tumors of the kidney, renal
pelvis and ureter. In: Atlas of Tumor Pathology. Washington, D. C.: Armed Forces Institute of Pathology, 2nd series, fasc. 12, pp. 31-59, 1975. 2. Thompson, M. R., Emmanuel, I. G., Campbell, M. S. and Zachary, R. B.: Extrarenal Wilms' tumors. J. Ped. Surg., 8: 37, 1973.
Extrarenal Wilms tumor in the inguinal canal
Reference Thompson and associates
2
Akhtar (1977) 3 and Madanat (1978) 4 and their associates (same pt.) Harms and L6hr 5 Taylor and associates 6 Orlowski and associates 7 Luchtrath and associates8 Okamura and associates 9 Lai and associates 10 Present case
Age-Sex
Side
3yrs.-M 4 yrs.-F 2mos.-M
Rt. Rt.
3yrs.-M 6mos.-M
Lt.
3yrs.-M 14 mos.-F 3 yrs.-F 5 yrs.-F 11 mos.-M
Initial Therapy
Results (mos.)
Actinomycin D/radiotherapy None Vincristine/actinomycin D
Recurrence* Recurrencet No evidence of recurrent disease (22) No evidence of recurrent disease (6)
Lt. Lt.
Vincristine/actinomycin D/radiotherapy None Vincristine/actinomycin D
Rt. Rt. Rt.
None Vincristine/actinomycin D
Lt.
Lt. Recurrencet No evidence of recurrent disease (34) Recurrence§
* Patient died. Local recurrence and metastatic spread to lungs and left renal hilus were noted at autopsy. t Local recurrence to right labia majora with no evidence of recurrent disease 24 months after local radiotherapy. t Pulmonary metastasis to left lower lobe (12 months later) with no evidence of recurrent disease 18 months after pulmonary radiotherapy and vincristine/actinomycin D. § Local recurrence to right inguinal region (11 months later) with no evidence of recurrent disease 8 months after actinomycin D.
EXTRARENAL WILMS TUMOR OCCURRING IN INGUINAL CANAL 3. Akhtar, M., Kott, E. and Brooks, B.: Extrarena! Wilms' tumor: report of a case and review of the literature. Cancer, 40: 3087, 1977. 4. Madanat, F., Osborne, B., Cangir, A. and Sutow, W.W.: Extrarenal Wilms' tumor. J. Ped., 93: 439, 1978. 5. Harms, D. and Lohr, J.: Inguinaler Wilms Tumor. Klin. Paed., 190: 54, 1978. 6. Taylor, W. F., Myers, M. and Taylor, W. R.: Extrarenal Wilms' tumour in an infant exposed to intrauterine phenytoin. Lancet, 2: 481, 1980. 7. Orlowski, J.P., Levin, H. S. and Dyment, P. G.: Intrascrotal Wilms' tumor developing in a heterotopic renal anlage of probable mesonephric origin. J. Ped. Surg., 15: 679, 1980. 8. Luchtrath, H., de Leon, F., Giesen, H. and Gok, Y.: Inguinal nephroblastoma. Virchows Arch. A, 405: 113, 1984. 9. Okamura, R., Tanaka, T. and Hagamaki, H.: A case of Wilms' tumor in the right inguinal region. Jap. J. Clin. Surg., 39: 419, 1984. 10. Lai, H. S., Hung, W. T. and How, S. W.: Extrarenal Wilms' tumor: a case report. J. Ped. Surg., 23: 454, 1988. 11. Heyns, C. F., Van Niekerk, D. J. T., Rossouw, D. J., Burger, E. C. and De Klerk, D. P.: Nephroblastoma in an ovotestis of a true hermaphrodite: a case report. J. Urol., 137: 1003, 1987.
785
12. tv'Ioyson, F. R., Maurus-Desmarez, R. and Gompel, C.: Tumeur de Wilms' mediastinale? Acta Chir. Belg., suppl. 2, p. 118, 1961. 13. Bell, D. A., Shimm, D. S. and Gang, D. L.: Wilms' tumor of the endocervix. Arch. Path. Lab. Med., 109: 371, 1985. 14. Ho, J., Ma, L. and Wong, K. C.: An extrarenal Wilms' tumour arising from an undescended testis. Pathology, 13: 619, 1981. 15. Sahin, A. and Benda, J. A.: Primary ovarian Wilms' tumor. Cancer, 61: 1460, 1988. 16. Potter, E. L.: Normal and Abnormal Development of the Kidney. Chicago: Year Book Medical Publishers, Inc., 1972. 17. McCauley, R. G. K., Safaii, H., Crowley, C. A. and Pinn, V. W.: Extrarenal Wilms' tumor. Amer. J. Dis. Child., 133: 1174, 1979. 18. Hamilton, W. J. and Mossman, H. W.: The urogenital system. In: Human Embryology: Prenatal Development of Form and Function, 4th ed. London: The MacMillan Press, Ltd., chapt. 12, pp. 377-436, 1978. 19. de Chadarevian, J. P., Fletcher, B. D., Chatten, J. and Rabinovitch, H. H.: Massive infantile nephroblastomatosis: a clinical, radiological, and pathological analysis of four cases. Cancer, 39: 2294, 1977. 20. Saito, S., Higa, I., Koyama, Y., Hatano, T., Hayakawa, M., Osawa, A. and Toda, T.: Immature renal tissue in inguinal canal. J. Urol., 142: 106, 1989.
