Clinicopathologic features of neuroendocrine carcinomas of the stomach: appraisal of small cell and large cell variants.

Abstract

To clarify the clinicopathologic features of neuroendocrine carcinomas (NECs) of the stomach, we reviewed 56 cases of surgically treated gastric carcinomas with a solid growth or with areas containing patterns characteristic for neuroendocrine (NE) tumors. Of the 56 cases reviewed, we selected 33 cases of NEC based both on histologic patterns common to NE tumors and on histochemical/immunohistochemical results. The average age of patients with NEC was 69.8 years (range, 44-92 years). The majority of patients were men (male-female ratio, 23:10). The most frequently affected site was the upper third (46%) of the stomach. Grossly, 9 cases of NEC were fungating and 24 were ulcerated. As compared with 23 patients with non-NEC tumors, the patients with NECs had a worse prognosis. Histologically, NECs had a variety of histologic patterns, including solid, organoid, trabecular, pseudoglandular, spindle cell, and rosettelike. Based on both cell size and morphologic features, we subdivided NECs into 2 variants, namely, small cell NEC and large cell NEC. Our series included 12 cases of small cell NEC and 21 cases of large cell NEC. Compared with small cell NECs, large cell NECs had a higher mitotic count, larger polygonal cells, a lower nuclear-cytoplasmic ratio, coarser nuclear chromatin, and more frequent conspicuous nucleoli. Large cell NEC was an aggressive tumor with a very poor prognosis (median survival time, 15.2 months; 1-year survival rate, 58%), which approached that for small cell NEC.