Cytodiagnosis of retroperitoneal primitive neuroectodermal tumour (PNET)--a case report.

A rare case of Retroperitoneal Primitive Neuro Ectodermal Tumour (PNET) in thirty years old female is presented. Fine needle aspiration cytology (FNAC) characterised by small round cells with scanty cytoplasm, poorly to well formed rosettes with neurofibrillary background; whereas periodic acid-schiff (PAS) rarely react with Primitive Neuro Ectodermal Tumour (PNET), prompted the diagnosis of PNET at cytology itself. Cytological appearances of PNET have been reviewed and the various differential diagnoses are discussed.