Extrapulmonary small cell neuroendocrine carcinoma of the paranasal sinuses: a case report and review of the literature.

Primary small cell neuroendocrine carcinoma of the paranasal sinuses is an extremely rare and distinctive tumor with aggressive clinical behavior. We report on a patient who had a small cell neuroendocrine carcinoma of the ethmoid sinus with invasion of the upper aspect of the right maxillary sinus and medial aspect of the right orbit. After 2 cycles of chemotherapy that were unsuccessful, he underwent radiotherapy with complete tumor remission. Local recurrence was not identified after 11 months of follow-up; however, distant metastasis developed 2 months after radiotherapy. The natural history, pathologic features, and choice of therapy for this rare neoplasm are discussed, along with a review of the published data.