Human Pathology: Case Reports

Combined goblet cell carcinoid and low grade appendiceal mucinous neoplasm

A composite adenoma-microcarcinoid is an intestinal neoplasm consisting of intermixed adenomatous and well-differentiated neuroendocrine components. Although subtle neuroendocrine differentiation is commonly seen in intestinal adenomas, colorectal tumors containing a significant percentage of morphologically recognizable neuroendocrine cells are uncommon. Unlike other mixed endocrine-glandular colorectal neoplasms, which are generally malignant, the glandular component of a composite adenoma-microcarcinoid is histologically benign, with a natural history that is generally favorable. We report an unusually large tubular adenoma associated with a microcarcinoid that arises in a backdrop of neuroendocrine hyperplasia, a rare phenomenon that has not been well documented in the literature.