Small cell carcinoma of the urinary bladder: a rare tumor with propensity for hepatic involvement

Small cell (neuroendocrine) carcinoma of the bladder is a rare entity, accounting for less than 1% of all bladder tumors. The authors report 2 new cases of the disease, both presenting with liver metastasis. In the first case, small cell carcinoma occurred in an 85-year-old woman as tumor recurrence of previous micropapillary carcinoma and urothelial carcinoma in situ, illustrating the common coexistence with conventional urothelial carcinoma. In the second case of a 58-year-old man, non-small cell tumor components were not observed. Accurate diagnosis of small cell carcinoma may be challenging. A panel of different antibodies, including neuron-specific enolase, chromogranin A, synaptophysin and CD56 (neural cell adhesion molecule) is recommended. In conclusion, small cell carcinoma represents a rare and aggressive form of bladder malignancy. As illustrated by the 2 cases and according to the literature review, the tumor shows a so far underrecognized propensity for hepatic involvement.

Treatment of uncommon malignant tumours of the bladder

PURPOSE OF REVIEW

Urothelial carcinoma is the most common histological type of bladder tumours. Nevertheless, its variants and less common types represent 20% of all bladder cancers. The objective was to update the recent publications on these rare diseases and to draw conclusions for clinical management.

RECENT FINDINGS

Recent retrospective studies have been published. They refine the description of histological patterns and of immunochemistry diagnosis. Taking into account the heterogeneity of these pathologies, several groups have benefited of increased knowledge such as sarcomas and lymphomas. The need of international collaboration to study prospectively some subgroups of tumours is crucial.

SUMMARY

Rare bladder cancers have generally poor outcome and in a majority of the cases surgery, namely cystectomy remains the most important curative treatment. Specific subgroups, as lymphoma, sarcoma and dedifferentiated epithelial tumours may benefit of molecular characterization and trials with targeted drugs.