Juxtarenal Wilms Tumor in an Adolescent

Pediatric Case Report Juxtarenal Wilms Tumor in an Adolescent Jennifer Gordetsky, Philip Katzman, and Hani Rashid A 17-year-old boy presented for evaluation of an abdominal mass. Imaging revealed a 12.5-cm left upper pole renal mass. Biopsy demonstrated a malignant neoplasm consistent with blastemal-type Wilms tumor. The patient received neoadjuvant chemotherapy followed by laparoscopic radical nephrectomy. Examination revealed an unremarkable kidney uninvolved by tumor abutted by a 7.3 cm encapsulated mass. Histology revealed a triphasic Wilms tumor (nephroblastoma) with favorable histology. This tumor was classified as a juxtarenal Wilms tumor, a rare form of extrarenal Wilms tumor, with only 7 cases described in the literature. We present the first case of a juxtarenal Wilms tumor described in an adolescent. UROLOGY 80: 922–924, 2012. © 2012 Elsevier Inc. CASE REPORT A 17-year-old boy presented to his primary care physician for evaluation of an abdominal mass. He felt a painless mass over his left upper abdomen with no history of trauma, and no significant change in size over a 2-month period. The patient denied any constitutional symptoms or hematuria. A computed tomography scan showed a 12 ⫻ 11.6 ⫻ 12-cm heterogeneous mass, originating either from the left kidney or from the left adrenal gland. The left renal vasculature was patent and the mass appeared to infiltrate the left psoas muscle. Urine and serum metanephrines and serum aldosterone were within the normal limits. Abdominal magnetic resonance imaging confirmed a 12.5 ⫻ 11.6-cm heterogeneous mass emanating from the left upper renal pole abutting the pancreas, spleen and adrenal gland (Figure 1). No lymphadenopathy was appreciated. A percutaneous needle core biopsy of the mass showed a small round blue cell tumor, and immunohistochemical stains supported a blastemaltype Wilms tumor (nephroblastoma). After completing debulking neoadjuvant chemotherapy with vincristine, dactinomycin, and doxorubicin, the patient underwent da Vinci-assisted laparoscopic radical nephrectomy with periaortic retroperitoneal lymph node dissection. Pathology revealed an intact radical nephrectomy specimen, with kidney and adrenal gland uninvolved by tumor. Immediately adjacent to the kidney, but not involving the renal parenchyma, was a 7.3 ⫻ 7 ⫻ 4 cm wellcircumscribed, gray-white, heterogeneous mass surrounded by a thick intact capsule that merged with the capsule of the kidney (Figure 2). Approximately 50% of the mass appeared necrotic. All lymph nodes were neg- Financial Disclosure: The authors declare that they have no relevant financial interests. From the Department and Pathology and Laboratory Medicine, and the Department of Urology, University of Rochester, Rochester, NY Reprint requests: Jennifer Gordetsky, M.D., Department of Pathology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 626, Rochester, NY 146428656. E-mail: [email protected] Submitted: April 16, 2012, accepted (with revisions): June 12, 2012 922 © 2012 Elsevier Inc. All Rights Reserved ative for carcinoma. Histology revealed a triphasic Wilms tumor with favorable histology (Figure 3). Given the location, this tumor was classified as an extrarenal Wilms tumor and, more specifically, a juxtarenal Wilms tumor. COMMENT Wilms tumor is the most common primary renal neoplasm of childhood, with an estimated incidence of 400 cases per year in the United States.1 Wilms tumor occurs in approximately 1 in every 10 000 children, making it the fourth most common pediatric malignancy in the United States.1 The peak incidence is between 2 and 5 years of age, and 90% are diagnosed by 6 years.1 The incidence of extrarenal Wilms tumor is rare, with a little over 50 cases reported in the literature, and only 16 documented in adults.2-4 Extrarenal Wilms tumor has been described in the retroperitoneum, inguinal region, mediastinum, chest wall, lumbosacral area, sacrococcygeal area, uterus, endocervix, vagina, ovary, round ligament, scrotum, and testis.5 Previous authors have created a separate diagnostic category for extrarenal Wilms tumor called “juxtarenal Wilms tumor,” in which the capsule of the tumor abuts the capsule of the kidney.4,5 Juxtarenal Wilms tumor is an exceptionally rare entity with only 7 cases being described in the literature. All the previously reported cases have presented in children age 72 months or less.4 We present the first case of a juxtarenal Wilms tumor in an adolescent. Thorough sectioning is important in the diagnosis of extrarenal Wilms tumor to rule out teratoma with a component of Wilms and other primitive mesenchymal tumors. Mimickers of extrarenal Wilms tumor include Wilms tumor arising from a supernumerary kidney and metastasis from an intrarenal Wilms tumor. Our tumor was treated with neoadjuvant chemotherapy causing a significant reduction in tumor size. The effects of chemotherapy included tumor necrosis and fibrosis. On both gross and histologic examination, the renal parenchyma was uninvolved by tumor, fibrosis, or necrosis, supporting 0090-4295/12/$36.00 http://dx.doi.org/10.1016/j.urology.2012.06.018 Figure 3. Histology of the tumor demonstrating a classic triphasic Wilms pattern. (Color version available online.) Figure 1. Magnetic resonance imaging showing a 12.5-cm heterogenous mass emanating from the left upper renal pole. (Color version available online.) Figure 2. Gross photograph of the radical nephrectomy specimen showing a large juxtarenal mass with sparing of the renal parenchyma and adrenal gland (arrow). (Color version available online.) the diagnosis of a juxtarenal Wilms tumor. The tumor was classified as stage 2 due to the presence of perirenal soft tissue involvement. UROLOGY 80 (4), 2012 Intrarenal Wilms tumors are thought to arise from precursor foci of nephroblastomatosis; however, there is no consensus on the origin of extrarenal Wilms tumors. Extrarenal Wilms tumors possibly arise from heterotopic metanephric blastemal rests or mesonephric duct remnants.5 Juxtarenal Wilms tumor is thought to arise from extrusion of subcapsular metanephric blastema.4 Despite extensive sampling of the pericapsular renal parenchyma, we were unable to identify any blastemal rests to support this theory. On initial imaging, it was unclear whether the tumor was arising from the kidney or the adrenal gland. The differential diagnosis included lymphoma, sarcoma, neuroblastoma, renal tumors, and adrenal tumors. Biopsy was used to help direct treatment, and showed a small round blue cell tumor, which included a differential diagnosis of lymphoma, Ewing’s sarcoma/primitive neuroectodermal tumor, rhabdomyosarcoma, and desmoplastic small round cell tumor. Immunohistochemical studies have shown CD56, CD57, CK22, CK18, CK8, epithelial membrane antigen, and smooth muscle actin to be useful in the accurate diagnosis of Wilms tumor in small biopsy specimens.2 Our tumor was positive for CD56 and Wilms tumor 1 (WT-1) protein, supporting the diagnosis of Wilms tumor.6 CD99 showed focal weak staining, which would be strongly diffusely positive in cases of Ewing sarcoma/primitive neuroectodermal tumor.6 Myogenin and desmin were negative, eliminating rhabdomyosarcoma and desmoplastic small round cell tumor.6 Although our case showed strong blastemal staining for the WT-1, this marker has been shown to have variable expression in both conventional and extrarenal Wilms tumors.2 Our tumor also had an abnormal composite karyotype with deletion of 5p, deletion of 20q, and an abnormal 17q. The tumor did not have a WT-1 mutation, which occurs 10% of the time in sporadic (nonsyndromic) Wilms tumors.1 Percutaneous needle core biopsy, along with immunohistochemical stains, was useful in correctly diagnosing a Wilms tumor. Neoadjuvant chemotherapy was chosen 923 due to concern based on imaging that the tumor had involved other retroperitoneal organs or might result in removal of adjacent organs due to tumor size. Neoadjuvant chemotherapy allowed for successful debulking before nephrectomy, decreased the chance of tumor spillage because of the fibrosed capsule, and prevented the potential removal of adjacent organs. Robotic-assisted laparoscopic radical nephrectomy with periaortic retroperitoneal lymph node dissection was performed without rupture to the tumor capsule. After successful debulking neoadjuvant chemotherapy, partial nephrectomy was considered as an option and was discussed at a multidisciplinary conference that included pediatric urologists, medical oncologists, and radiation oncologists. There was concern that a partial nephrectomy might increase the chance of intraoperative tumor spillage and, therefore, a radical nephrectomy was recommended as the safest treatment modality. At our institution, robotic/laparoscopic surgery is the “gold standard” for most renal surgeries in adults. With the increased wealth of experience in laparoscopic surgery, our urologists are now applying these minimally invasive techniques to renal surgeries in select children and adolescents. This trend toward minimally invasive urologic surgeries in the pediatric population has been well reported in the literature.7-9 The prognosis for conventional Wilms tumors is excellent with a greater than 90% overall survival.1 The data on extrarenal Wilms tumor suggests a similar prognosis. A retrospective review by Coppes et al5 of 34 patients with extrarenal Wilms tumor showed a 2-year survival of 82%. Most cases were treated with chemotherapy with or without radiation therapy. Unfortunately, reported cases of juxtarenal Wilms tumor were 924 considered a separate entity and excluded from the analysis. In all 7 previously reported juxtarenal Wilms tumors, there was no evidence of disease with follow-up ranging from 7 to 72 months.4 In our case, the patient responded well to neoadjuvant chemotherapy, with a decrease in the size of the renal mass from 12 to 7 cm. The patient is currently being managed with adjuvant chemotherapy and radiation. The prognosis of juxtarenal Wilms tumor in an adolescent remains unknown. References 1. Robbins SL, Cotran RS, Perkins JA, et al. Robbins and Cotran Pathologic Basis of Disease, 8th ed. Philadelphia: Saunders/Elsevier; 2010. 2. Kadota K, Haba R, Kushida Y, et al. Adult extrarenal Wilms’ tumor mimicking mixed epithelial and stromal tumor in the retroperitoneum: a case report with immunohistochemical study and review of the literature. Pathol Oncol Res. 2009;15:665-669. 3. Ratnam GV, Abu-Eshy S, Morad N, et al. Adult extrarenal Wilms’ tumour: a case report and review of literature. West Afr J Med. 2006;25:75-78. 4. Ngan KW, Shaari S, Subramaniam T. Juxtarenal/pararenal Wilms’ tumour in a six-year-old Malay girl. Singapore Med J. 2009;50:e329e331. 5. Coppes MJ, Wilson PC, Weitzman S. Extrarenal Wilms’ tumor: staging, treatment, and prognosis. J Clin Oncol. 1991;9:167-174. 6. Sebire NJ, Gibson S, Rampling D, et al. Immunohistochemical findings in embryonal small round cell tumors with molecular diagnostic confirmation. Appl Immunohistochem Mol Morphol. 2005;13: 1-5. 7. Javid PJ, Lendvay TS, Acierno S, et al. Laparoscopic nephroureterectomy for Wilms’ tumor: oncologic considerations. J Pediatr Surg. 2011;46:978-982. 8. Orvieto MA, Large M, Gundeti MS. Robotic paediatric urology. BJU Int. 2012;110:2-13. 9. Casale P, Kojima Y. Robotic-assisted laparoscopic surgery in pediatric urology: an update. Scand J Surg. 2009;98:110-119. UROLOGY 80 (4), 2012