Reevaluation of pulmonary neoplasms resected as small cell carcinomas. Significance of distinguishing between well-differentiated and small cell neuroendocrine carcinomas.

The clinicopathologic features of 50 cases of surgically resected small cell carcinoma were reevaluated (doubly blinded). Two pulmonary carcinomas were excluded because neuroendocrine features could not be demonstrated; two additional cases also were excluded because the tumors grossly invaded the chest wall and their pulmonary origin was not substantiated. Thirty-four tumors were confirmed to be small cell neuroendocrine carcinoma (SCNC). Only seven of 11 (64%) patients with T1N0,T2N0 tumors survived more than 1 year; one of 11 (9%) patients survived more than 2 years. In 12 cases, the diagnosis was changed to well-differentiated neuroendocrine carcinoma (WDNC). Of these, nine of nine (100%) patients with T1N0,T2N0 tumors survived more than 1 year; six of eight (75%) patients survived more than 2 years. These observations strongly indicate that a significant number of long-term survivors with the diagnosis of small cell carcinoma may, in fact, have a distinctly less aggressive type of pulmonary neuroendocrine carcinoma. It was concluded that the distinction between small cell and well-differentiated types of neuroendocrine carcinomas has significant prognostic and therapeutic implications.