Objectives: Primary primitive neuroectodermal tumor (PNET) of the kidney is an extremely rare entity and the case is presented to highlight the histological diagnostic problems.
Methods and results: A 23-year-old female presented with a lump in the left hypochondrium that had appeared 3 months, earlier, which suggested a malignancy on radiological investigation. The nephrectomy specimen revealed a large tumor mass with only a small portion of normal renal parenchyma. Histology showed a small cell malignant tumor and the diagnosis of PNET (primary of kidney) and small cell carcinoma were suspected. The tumor showed NSE and vimentin positivity and cytokeratin negativity, which conformed with the diagnosis of PNET.
Conclusion: The biological behaviour of PNET is more aggressive, with rapid progression and infiltration into the surrounding tissues and distant metastases. Thus it differs from the small renal cell malignancies and hence recognition of this tumor as a distinct entity is essential.