Primary primitive neuroectodermal tumour of the urinary bladder: a clinico-pathological study emphasising...

Primary primitive neuroectodermal tumours (PNETs) of the bladder are extremely rare and aggressive neoplasms, and only six examples have been reported in the literature. The case of a 21-year-old woman, who remains disease free 3 years after tumour resection, is reported here. Morphological features were found to correspond to a small round blue cell tumour without rosette formation and with extensive areas of necrosis. Strong expression of CD99, vimentin and CD117 (c-kit), and focal reactivity to cytokeratin and S-100 protein was observed in tumour cells. Ultrastructurally, sparse neurosecretory granules were observed. Diagnosis of PNET was supported by molecular genetic analysis, showing the EWS-FLI-1 fusion transcript type 2 by RT-PCR and EWS gene rearrangement by fluorescence in situ hybridisation. A normal genetically balanced genotype was shown by comparative genomic hybridisation, which, together with the expression of c-kit, a known therapeutic target for imatinib, may have prognostic and therapeutic implications.