Indian Journal of Pathology and Microbiology

: 2012  |  Volume : 55  |  Issue : 4  |  Page : 587--588

A case of primitive neuroectodermal tumor of the kidney and review of the literature

Sanish S Shringarpure1, Murali Venkatraman1, T Raja2, Rama Mani3,  
1 Department of Urology, Apollo Hospital, Chennai, India
2 Department of Oncology, Apollo Hospital, Chennai, India
3 Department of Pathology, Apollo Hospital, Chennai, India

Correspondence Address:
Sanish S Shringarpure
27,Vishal Nagar, Bijapur road, Solapur - 413 004, Maharashtra

How to cite this article:
Shringarpure SS, Venkatraman M, Raja T, Mani R. A case of primitive neuroectodermal tumor of the kidney and review of the literature.Indian J Pathol Microbiol 2012;55:587-588

How to cite this URL:
Shringarpure SS, Venkatraman M, Raja T, Mani R. A case of primitive neuroectodermal tumor of the kidney and review of the literature. Indian J Pathol Microbiol [serial online] 2012 [cited 2022 Jun 30 ];55:587-588
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A 21-year-old male was referred for vague abdominal pain and hematuria. Ultrasound examination of the abdomen showed a left renal mass homogenously hyperechogenic compared with the rest of the renal parenchyma. A computerized tomographic (CT) scan abdomen showed a 7 × 5 × 7 cm heterogeneously enhancing mass lesion arising from cortex of the left kidney extending from the midpole to the lower pole with fine calcification and necrosis [Figure 1]. CT guided fine needle aspiration cytology (FNAC) of the lesion was inconclusive. Chest X-ray was normal. He underwent left radical nephrectomy. There were no lymph nodes and renal vein and inferior vena cava were free of any thrombus. The pathological staging after radical nephrectomy was pT2N0M0. Cut section of the specimen showed a circumscribed solid lesion 8 × 8 × 6 cm occupying the cortex and medulla of the mid-segment showing variegated appearance with necrotic and hemorrhagic areas.{Figure 1}

Histopathology showed multinodular lobulated neoplasm within the renal parenchyma. The lobules were made of all round cells with indistinct cytoplasm, round nuclei with vesicular chromatin and indistinct arranged around central eosinophilic fibrillary material in the form of rosettes [Figure 2]. Periodic acid Schiff (PAS) stain showed focal intracytoplasmic positivity, which was diastase positive. Immunohistochemistry was positive for vimentin and CD 99 while cytokeratin, desmin, CD 56 and synaptophysin were negative [Figure 3]. He received chemotherapy with endoxan, vincristine, and adriamycin for six cycles. Follow up of 1 year did not show any local recurrences and distant metastases after which the patient was lost to follow-up.{Figure 2}{Figure 3}

Primitive neuroectodermal tumor of the kidney is a rare entity. The differentiation from other renal malignancies is important for prognosis. The differential diagnosis includes extraosseous Ewing's sarcoma (EWS), Wilm's tumor, carcinoid tumor, neuroblastoma, clear cell sarcoma of the kidney, lymphoma, round cell tumor, small cell variant of osteosarcoma. The clinical symptoms and signs are nonspecific, comprising of flank pain or vague abdominal pain, hematuria and palpable mass. Laboratory findings are almost unremarkable. Radiologically, primitive neuroectodermal tumor (PNET) typically presents as large and heterogenous mass with low central density areas due to necrosis and areas of high attenuation due to hemorrhage. [1] There have been few reports of intratumoral calcification. On light microscopy, PNET consists of monomorphic small round cells giving a synctial appearance. Some tumor cells may arrange themselves as perivascular pseudo-rosettes or Homer-Wright rosettes. The Homer-Wright type rosettes, commonly scarce in number or less defined in extra skeletal EWS, are a typical histological feature for PNET and can address the diagnosis although they can be found also in neuroblastoma. [2] Immunohistochemistry and molecular studies have a key role in establishing an accurate diagnosis and in differentiating from other small round cell tumors. PNETs are usually diffusely positive for CD 99 [3] and two-thirds are positive for Fli-1, which detects the expression of chimeric EWS FLI-1 protein. Approximately 20% of the cases are also positive for cytokeratins. Other immunohistochemical markers, for example, S-100 protein, synaptophysin, neuron specific enolase, secretogranin II, keratin, gene product 9.5 provide further evidence for the neuroepithelial line of differentiation. PNETs are negative for markers of muscle differentiation (MyoD1 or myogenin) and lymphoid differentiation (leukocyte common antigen) and WT-1, which is a marker commonly expressed by Wilm's tumor. In our case, immunohistochemistry was positive for vimentin and CD 99 while cytokeratin, desmin, CD 56 and synaptophysin were negative. Molecular studies to demonstrate the reciprocal translocation of chromosomes 11; 22 (q24; q12), which is present in approximately 85% of PNET and results in fusion of the EWS gene with the FLI-1 gene, can further increase the diagnostic confidence. [4] This was not done in our case as the specimen was fixed in formalin and techniques as fluorescent in-situ hybridization, are not available in our institution.

Treatment strategies for renal PNET include surgery, chemotherapy and radiotherapy. The current standard chemotherapy includes doxorubicin, vincristine, and cyclophosphamide alternated with ifosfamide and etoposide. Postoperative radiotherapy may be added when the surgical margins are involved by the tumor. Renal PNET is an aggressive tumor, with a tendency toward local recurrence and early metastases to regional lymph nodes, lungs, liver, and bone. The overall 5-year disease-free survival rate is reported to be between 45% and 55% but in patients with metastases at initial presentation, the median relapse-free survival is reduced to only 2 years.


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