Metastatic primitive neuroectodermal tumor to the kidney

Primary primitive neuroectodermal tumour of the kidney in adults

Primitive neuroectodermal tumour (PNET) is a neural crest tumour derived from neuroectoderm. Renal PNET is a very rare tumour occurring during childhood or adolescence. We report two cases of PNET involving kidney in adults. Presenting signs and symptoms include abdominal/flank pain and/or haematuria. Microscopy reveals the tumour consisted of small round cells with round nuclei and scant cytoplasm. Diagnosis was confirmed by immunohistochemistry with diffuse membranous positivity of tumour cells with CD99. As these tumours have an aggressive clinical course with rapid death in many reported cases, it is important to differentiate them from other small round-cell tumours.

Primitive neuroectodermal tumor of the kidney

We report a 21-year-old man with a primitive neuroectodermal tumor (PNET) of the kidney that was difficult to distinguish from other small round cell tumors, e.g., small cell carcinoma, malignant lymphoma, and Wilms' tumor. Pathologically, a primitive rosette-like pattern was shown by H&E staining; expression of MIC-2 was indicated by an immunohistochemical test; rather primitive organelles were observed by an ultrastructural method; and translocation of chromosome 22 was confirmed by FISH. We therefore diagnosed the current case as PNET. The patient had undergone a right radical nephrectomy more than 1.5 years earlier. After neither metastases nor recurrences for 0.5 year, imaging examinations revealed masses in his liver. He received chemotherapy and underwent surgery again, but the masses were not composed of viable tumor cells. PNET of the kidney is extremely rare; fewer than 30 cases have been reported in the English literature, and there are few data on the expression of p53, ki67, and bcl2. We investigated the relationships between these markers in the current case using immunohistochemical tests and observed strong expression of p53, Ki-67, and bcl-2. Such results generally indicate poor prognosis, and the patient eventually had some masses in his liver, but no viable tumor cells were found. The prognostic significance of these various markers in PNET of the kidney still remains unclear, but p53, ki-67, and bcl-2 might not be so important as indicators of prognosis in the kidneys as they are in other organs. Further studies are needed to investigate this, and we hope that the patient recovers completely.