Lessons to be learned: a case study approach. Paraganglioma of the urinary bladder.

Primary paraganglioma arises infrequently in the urinary bladder. We present here the clinicopathological, immunohistochemical and ultrastructural findings in a 23-year-old Saudi female. She was hospitalised because of gross haematuria over the previous seven days. The intravenous urogram revealed a filling defect in the urinary bladder. Cystoscopy disclosed a non-papillary tumour arising from the roof of the bladder neck. Transurethral resection was, accordingly, performed--but marked fluctuation in blood pressure was observed during the procedure. The histopathological findings of trabeculae and small nests of plump oval to spindle cells with a clear to acidophilic cytoplasm, forming an organoid pattern and demonstrating inconspicuous mitotic activity, were diagnostic of paraganglioma of the urinary bladder, the diagnosis was confirmed by means of immunohistochemical and ultrastructural studies. The endocrine markers chromogranin A and neuron-specific enolase were positive in chief cells; sustentacular cells at the periphery of neoplastic cell clusters were positive for S-100 protein. Neurosecretory granules were identified by electron microscopic examination. It is emphasised that, currently, there are no anatomico-pathological criteria to distinguish benign and malignant forms of the disease. Post-surgical recovery was uneventful in this case. Recurrence and metastases, though infrequent, have been reported in the literature; therefore, radiation therapy may be an important adjunct--and long-term follow-up is mandatory.