Paraganglioma of the urinary bladder: an immunohistochemical study and report of an unusual association with intestinal carcinoid.

Two cases of paraganglioma of the urinary bladder are reported. Their immunohistochemical profiles and the clinical features are compared with other cases in the literature. The three pan-endocrine markers (neuron-specific enolase, synaptophysin and chromogrannin) were positive in both cases. Positivity to other neuropeptides (including the present two cases and those in literature) includes adrenocorticotropic hormone (three out of five cases), calcitonin (two out of nine cases), gastrin (two out of six cases), glial fibrillary acidic protein (one out of five cases), glucagon (two out of six cases), serotonin (five out of nine cases), and somatostatin (four out of eight cases). A previously unmentioned association between paraganglioma of the urinary bladder and carcinoid in the gastrointestinal tract is noted in one of the present cases. This peculiar association highlights the importance of multiplicity of tumours of the neuroendocrine system other than the classical multiple endocrine neoplasia syndromes.