Primary carcinoma of the small intestine. A clinicopathologic and immunohistochemical study

A clinicopathologic and immunohistochemical study of fifty‐two primary carcinomas of the small intestine (20 duodenal, 18 jejunal, and 14 ileal) was performed. Most of these neoplasms were located in the proximal duodenum, proximal jejunum, and distal ileum. Most of these tumors produced both sialomucin and sulfomucin, although the adjacent mucosa showed hyperplastic changes with increased sialomucin secretion. Argyrophil cells were recognized in seven duodenal (35%), 13 jejunal (72%), and nine ileal (69%) carcinomas. Eighteen of the 29 tumors showing positive argyrophil reactions also had argentaffin cells. The common features of mucins and endocrine cells in these tumors suggest the multipotency of small intestinal carcinoma. The prognosis correlated with the histologic type, carcino‐embryonic antigen (CEA) grading, invading pattern of tumor margins, and vascular permeation and regional lymph node metastasis.