Renal Primitive Neuroectodermal Tumour: Case Report of a Rare Entity.

The peripheral Primitive Neuroectodermal Tumour (PNET) is a member of the family of small round cell tumours. PNET is more aggressive in kidney when compared to the other sites. It usually presents in childhood or adolescence. It has an aggressive clinical course and may process towards metastatic disease culminating in death. A 24-year-old female presented with left sided abdominal swelling. Abdominal ultrasound confirmed a heterogeneous left renal mass. Consequently the patient underwent nephrectomy of left kidney and left oophorectomy. Grossly, the tumour involved almost entire kidney, showed multi-lobular, grey, glistening appearance with focal haemorrhagic areas. Histologically, the tumour cells were arranged in diffuse infiltrating sheets, cohesive lobules, Homer-Wright rosettes and perivascular pseudo-rosettes. Individual tumour cells were small round cells with scant cytoplasm and round nuclei having dispersed chromatin. Features were suggestive of PNET. Immunohistochemistry showed tumour cells displaying strong membrane positivity for MIC 2. Renal PNET needs to be differentiated from other primary and metastatic renal round-cell tumours. Most of the cases of renal PNET have poor response to standard treatment of combined surgical resection, post-operative irradiation, and chemotherapy. PNET is a rare primary tumour in the kidney. Histopathological diagnosis has to be confirmed by immunophenotyping of the tumour cells.