Primary duodenal carcinoma arising in a non-vaterian tubulo-villous adenoma. A case report with immunocytochemical analysis and review of the literature.

Primary duodenal carcinoma and duodenal adenoma are rare tumours. Duodenal carcinoma makes up about 0.3% of all malignant tumours of the gastrointestinal tract (Alwmark et al. 1980; Spira et al. 1977). The present paper describes a duodenal carcinoma arising in a mixed tubulo-villous non-Vaterian adenoma in a 68 year old male. Immunocytochemical analysis revealed evidence of neuroendocrine differentiation in both adenoma and carcinoma. In a review of the literature a correlation between the size of adenoma and the probability of concomitant carcinoma is demonstrated. Duodenal adenoma measuring more than 4 cm in diameter should be considered potentially malignant.