A case of solid and papillary neoplasm of a mesocolonic ectopic pancreas in a 13-yr-old girl is presented. An 8-cm, well-encapsulated, and partly calcified tumor which protruded from the mesocolon was resected surgically. Histologically, the tumor showed either solid sheets or papillary arrangements (around the vascular core) of uniformly small cells with alpha 1-antitrypsin-positive cytoplasm. Some of the tumor cells had zymogenlike granules, suggesting acinar cell differentiation. At the base of this tumor, small pancreatic tissues (islet, acinar, and ductular cells) were detected in the mesocolonic tissue. Incidences of both ectopic pancreas outside the gastrointestinal wall and solid and papillary neoplasm of the pancreas are rare, and this is the first case reported in the literature.