Primary PNET of kidney: report of two cases and review of literature.

ABSTRACT

PNET of the kidney is a rare tumor with only a few published reports. In view of poorer prognosis and different therapeutic approach, renal PNET should therefore be differentiated from other primary renal neoplasma such as Wilms tumor, renal neuroblastoma and malignant rhabdoid tumor which on histology resemble renal PNET. Two cases of renal PNET have been described in this report. Cut surface of the tumor in both cases was greyish white lobulated, with multiple tiny cystic areas. Histologically, tumor consisted of loosely cohesive sheets of small to medium sized monomorphic cells with round nuclei and little cytoplasm. Tumor cells showed diffuse strong membrane positivity for MIC2 and focal weak to moderate positivity for NSE and vimentin. Renal PNET should therefore be included in differential diagnosis of rapidly enlarging renal lumps presenting with local infiltration and aggressive behaviour, particularly in children and young adults. Diffuse strong membrane positivity for MIC2 in PNET is helpful in differentiating it from other primary renal neoplasms.