Papillary and solid neoplasm of pancreas in a child. Report of a case in which acinar differentiation was demonstrated by immunohistochemistry and electron microscopy.

: A case of exocrine carcinoma of the pancreas in a 13-year-old girl is presented. A small tissue biopsy obtained from the duodenal lesion through a duodenofiberscope confirmed a carcinoma of the head of the pancreas, for which pancreaticoduodenectomy was successfully performed. The tumor showed histological features of a papillary and solid neoplasm, but amylase and alpha 1-antitrypsin were detected in the tumor cells by a modified PAP method. Electron microscopic examination of the tumor cells disclosed both acinar and ductal differentiation. Polygonal cells showing acinar differentiation contained zymogen granules, while columnar cells arranged in a papillary pattern contained abundant intracytoplasmic filaments and lacked zymogen granules. Stacks of annulate lamellae were frequently noticed in both types of the tumor cells. This case indicates the importance of immunohistochemistry and electron microscopy for the detection of acinar and ductal differentiation of carcinoma of the pancreas in childhood.