|Year : 2015 | Volume
| Issue : 4 | Page : 934-936
Adult Wilms' tumor: A case report with review of literature
Amit V Varma, Kamal Malukani, Preeti Rihal, Shirish S Nandedkar
Department of Pathology, Sri Aurobindo Medical College and Post Graduate Institute, Indore, Madhya Pradesh, India
|Date of Web Publication||15-Feb-2016|
Department of Pathology, Sri Aurobindo Medical College and Post Graduate Institute, Indore Ujjain Highway, Indore - 453 111, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
Wilms' tumor presents a diagnostic problem due to its rare occurrence in adults. Most of the cases of adult Wilms' tumor are diagnosed unexpectedly following nephrectomy for renal cell carcinoma. We are reporting herein a rare case of Adult Wilms' tumor of kidney with triphasic histology and distant metastasis to lung.
Keywords: Adult, kidney, Wilms′ tumor
|How to cite this article:|
Varma AV, Malukani K, Rihal P, Nandedkar SS. Adult Wilms' tumor: A case report with review of literature. J Can Res Ther 2015;11:934-6
| > Introduction|| |
Wilms' tumor is the most common primary malignant renal tumor of childhood. It accounts for approximately 5-6% of the neoplasm in children, but it is extremely rare in adults, representing only 0.5% of all renal neoplasms.  Only 3% of Wilms' tumors are reported in adults  and most are diagnosed unexpectedly following nephrectomy for presumed renal cell carcinoma. 
| > Case report|| |
A 48-year-old male presented with fever and left flank pain for 2 months. On examination, a huge tender mass was palpable in the left upper abdomen. The hematological and biochemical parameters were within normal limits. Ultrasonography of abdomen showed a large heterogeneous mass in the upper pole of left kidney. Contrast-enhanced computed tomography of chest and kidneys, ureters, and bladder revealed an extremely large (15 × 20 × 17 cm) lobulated heterogeneously enhancing irregular mass within the left hypochondrium, arising from the upper pole of left kidney. The mass showed large irregular hypodense area of necrosis [Figure 1]a]. It was elevating the left dome of the diaphragm and was displacing the spleen anteriorly beneath the abdominal wall [Figure 1]b]. There was suspicion of adherence of mass to the superior aspect of splenic capsule. Mass was also displacing the stomach and pancreas anterolaterally to the right and the adjacent bowel loops medially and inferiorly [Figure 1]b and c]. Left renal artery and vein were unremarkable. Left adrenal gland was not separately visualized. Mass was closely abutting the aorta. There was evidence of few mesenteric and retroperitoneal lymph nodes of subcentimeter size. Minimal left pleural effusion and pelvic free fluid was seen. Also small nodular fibroatelectatic opacities were noted in the apical segment of upper lobe of left lung. Right kidney, renal artery, renal vein, and adrenal were unremarkable.
|Figure 1: (a) Multidetector computed tomography (MD-CT) post-contrast sagittal image showing large mass with necrotic areas arising from upper pole of left kidney displacing diaphragm and spleen. (b and c) MD-CT post contrast axial image showing normal right kidney. Left kidney mass displacing spleen and pancreas|
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A radical surgery was performed. The specimens received in surgical pathology department were: (1) Left kidney with a large mass at the upper pole and adhered spleen; kidney with mass measured 25.5 × 22 × 14 cm and spleen measured 16 × 9× 4 cm. External surface of the kidney was bosselated, renal capsule was torn and tumor was grossly invading perirenal fat. Cut-section showed a large ill-defined tumor replacing the upper half of kidney. Lower half of the kidney was normal with clear corticomedullary distinction [Figure 2]. The tumor was solid, partially lobulated, variegated appearance, soft-to-firm in consistency, with areas of cystic degeneration, necrosis, and hemorrhages.(2) A piece of left lung measured 7 × 6× 2.3 cm. Cut-section showed a grayish, firm, solid mass measuring 5 × 4.2 × 2 cm. (3) Piece of distal pancreas measured 7 × 4.5 × 2 cm. Cut-section showed a small rim of tumor tissue at the periphery, not invading the pancreas.(4) A piece of intercostal muscle and soft tissue, measured 3.5 × 2.2 × 0.6 cm. Cut-surface was grayish white in color and soft in consistency.
|Figure 2: Photograph of bosselated mass (blue arrow) arising from upper half of kidney with adhered spleen (red arrow). Lower half of kidney is grossly unremarkable (yellow arrow)|
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Microscopy revealed Wilms' tumor with triphasic histology; sheets of round cells having hyperchromatic nuclei and scanty cytoplasm representing blastemal component with primitive tubule and glomeruli formation [Figure 3]a], admixed with mesenchymal component showing focal chondroid differentiation [Figure 3]b] and epithelial component showing cuboidal to columnar cells [Figure 3]c]. Large areas of necrosis and hemorrhages were evident. Tumor was invading renal capsule, splenic capsule, and peripancreatic tissue. Lung tissue, intercostal muscle, and fibrocollagenous tissue also showed tumor of similar morphology [Figure 3]d].
|Figure 3: Photomicrograph showing (a) Wilms' tumor with well-defined borders pushing renal parenchyma (h and e, ×40). (b) Blastemal and mesenchymal component with chondroid differentiation (h and e, ×400). (c) Epithelial component showing cells having more abundant cytoplasm and forming tubules (h and e, ×400). (d) Metastasis of Wilms' tumor in lung tissue (h and e, ×40). h and e = Hematoxylin and eosin|
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Diagnosis of adult Wilms' tumor of left kidney with distant metastasis to left lung was made.
Postoperative adjuvant chemotherapy was given followed by radiotherapy as on lines of Wilms' tumor management protocol. The patient has been well without recurrence for 8 months after surgery.
| > Discussion|| |
Wilm's tumor is named after the German surgeon Dr Carl Max Wilhelm Wilms. It is also called nephroblastoma as it originates from the totipotent cells of the metanephrogenic blastemal remnants. Kilton et al.,  have given six strict diagnostic criteria for adult Wilm's tumor: (i) It should be a primary renal tumor; (ii) primitive blastemal spindle or round cell component should be present; (iii) formation of abortive or embryonal tubules or glomerular structures; (iv) tumor should not show any area diagnostic of renal cell carcinoma; (v) there should be pictorial confirmation of histology; and (vi) patient's age should be more than 15 years. The index case met all the above mentioned criteria. Rarely, Wilms' tumor and renal cell carcinoma can be found simultaneously in the same kidney.
Histologically, adult Wilms' tumor composed of three types of cells-blastemal, stromal, and epithelial. Although the presence of all the three types of cells in the same case is uncommon.  Blastemal component is usually predominant in adult Wilms' tumor. Very few cases of adult Wilms' tumor with classic triphasic histology have been reported in Indian literature. , Thorough sectioning is required for the search of different components in a case of Wilms' tumor. More diffuse the anaplasia, more unfavorable is the histology and poorer is the prognosis. Masuda et al., have suggested that calcification may be a sign of slow tumor growth and possibly a favorable prognosis in cases of adult Wilms' tumor.  Calcified tumors may be relatively large, tend to be localized, and histologically well-differentiated.
An adult Wilm's tumor with mainly epithelial differentiation should be differentiated from metanephric adenoma and renal cell carcinoma.  Similarly, differential diagnosis of adult Wilm's tumor with predominantly blastemal component is small round blue cell tumors (including lymphoma, primitive neuroectodermal tumor, and rhabdomyosarcoma), metastatic small cell carcinoma from lung, immature teratoma, renal cell sarcoma, and poorly differentiated renal cell carcinoma with large sarcomatous component resembling blastema.  Renal cell carcinoma may have undifferentiated or sarcomatous areas which should be distinguished from blastemal or mesenchymal component of Wilms' tumor, respectively. 
Adult Wilms' tumor is different in many ways when compared with pediatric Wilms' tumor; (i) adults present with local pain and hematuria usually, in contrast to palpable boggy mass which is a more common presentation in children; (ii) adult Wilms' tumor is larger and ill-defined without sharp margins and with areas of necrosis and hemorrhages. Extension into the adjacent retroperitoneum is often present; (iii) adult Wilms' tumor have a more aggressive clinical course and a higher tumor stage at presentation. About half of the patients have stage 3 or 4 disease at presentation.  Metastasis rates for adults and children were 29 and 10%, respectively, in a study.  Lungs are the most common sites for metastatic spread, other sites include liver, bone, lymph nodes, skin, orbit, and the contralateral kidney.  However, adults do not need a more aggressive treatment for Wilms' tumor as compared to children.
In contrast to the pediatric population, majority of the adult patients are operated primarily. It is not possible to achieve a safe diagnosis by imaging studies alone in adults.  Fine-needle aspiration cytology offers a simple and effective way to establish preoperative diagnosis and plan patient management.  Presence of more than one cell type of population (blastemal, stromal, or mesenchymal) in aspirate from a renal mass in an adult should alert the pathologist to consider the uncommon occurrence of Wilms' tumor. It is particularly helpful in cases of primarily inoperable tumor or stage IV disease. Preoperative chemotherapy can be given to such patients, which may result in regression of the tumor and in operability. Also cytogenetic studies can be carried out on aspirated material. 
In a series of 30 patients presented by Reinhard et al., event-free survival of 57% and overall survival of 83% was reported.  They found that improvement of prognosis is due to central monitoring of the patients and multimodal therapy according to the pediatric protocol.  Multiple factors may contribute to the poor outcome including the unfamiliarity of adult oncologists and pathologists with Wilms' tumors, lack of standardized treatment, and consequent delays in initiating the appropriate risk-adapted therapy. 
| > Conclusion|| |
In an adult patient presenting with flank pain, and a renal mass on imaging, though rare, possibility of Wilms' tumor should also be considered.
| > References|| |
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[Figure 1], [Figure 2], [Figure 3]