[Primary neuroectodermal tumor (PNET) of the kidney: 26 cases. Current status of its diagnosis and treatment]

To report a case of primitive neuroectodermal tumor (PNET) of the kidney and review the literature and the 25 cases previously reported as PNET.

A 39-year-old man who consulted for nephric colic is described. Ultrasound evaluation disclosed a mass arising from the left kidney. The clinical, radiological and pathologic features, treatment and differential diagnosis of small cell tumors are discussed, as well as the important role of immunohistochemical techniques (positive staining with O13 or 12E7 antibodies) and cytogenetic analysis [a characteristic chromosomal translocation t(11;22) (q24;q12) or variant translocation, such as t(21;22) (q22;q12), may be detected by fluorescence in situ hybridization (FISH) or polymerase chain reaction-reverse transcriptase (PCR-RT)].

Survival of our patient was 20 months. Only three of the 25 previously reported cases had a longer survival: 60, 48 and 24 months. Mean survival was 10 months. 95.24% of the cases were positive for NSE. Immunostaining (CD99) was performed in 16 patients and was found to be positive in all cases. Cytogenetic and molecular analyses were performed in 11 cases; PCR-RT was negative in two, as well as in the case described herein.

PNET is a highly aggressive neoplasm that tends to recur locally and to metastasize. Despite the poor response to standard therapy combining surgical resection, postoperative irradiation and chemotherapy, the results might change due to current research on genetic therapy based on creating antisense oligonucleotides against the EWS-FLI 1 fusion gene.