Gastric small-cell carcinoma in Japan: a case report and review of the literature.

The authors encountered a patient with primary gastric small-cell carcinoma (primary gastric SCC). Histologic examination revealed combined carcinoma containing non-small-cell elements such as adenocarcinoma and squamous cell differentiation. On preoperative biopsy, only well-differentiated adenocarcinoma was collected. Since gastric SCC was first reported in 1976, this type of carcinoma has been detected in 54 patients in Japan. Concerning these cases, the authors reviewed the light and/or electron microscopic findings of neuroendocrine granules, positive reaction for neuron-specific enolase staining, and the histologic type of resected specimens. There were only three patients positive for neuron-specific enolase in which light and electron microscopy demonstrated neuroendocrine granules. However, 50 patients (approximately 93%) overall satisfied at least one of these findings. Concerning the histologic characteristics of the resected specimens, multidirectional differentiation was more markedly observed compared with that in SCC of the lung. Adenocarcinomatous and/or squamous differentiation was observed in more than half the cases, and preoperative biopsy suggested carcinoma other than SCC or undifferentiated carcinoma in several cases.