Small cell carcinoma presenting as an extrapulmonary neoplasm: sites of origin and response to chemotherapy.

Eight (4%) of 203 consecutive prospectively staged and treated patients with small cell carcinoma (SCC) had no evidence of pulmonary or mediastinal tumor on chest roentgenogram or at fiberoptic bronchoscopy at the time of diagnosis. There were two distinct clinical presentations in these SCC patients with exclusively extrapulmonary tumors. Four had discrete localized extrapulmonary neoplasms, presumably originating in these sites. In the other 4 cases with either regional or widely metastatic disease, no obvious primary tumor could be documented in the lungs or elsewhere. One complete and two partial responses to chemotherapy (duration 6 to greater than 11 mo) occurred in 6 evaluable patients. Two remaining patients were inevaluable for response because they received adjuvant chemotherapy after irradiation or excision of the primary tumor and are free of disease at 15 and 28 months. Results document two clinicopathologic entities of extrapulmonary SCC, more firmly establish that it can be responsive to chemotherapy, and encourage systemic therapy as part of initial treatment planning.