Goblet cell carcinoid of the appendix.

A 47-year-old man was admitted with appendicitis, and appendectomy was performed. On microscopic examination of the resected specimen, the presence of goblet cell carcinoid in the tip of appendix was revealed. This tumor showed an aggressive nature with perineural and vascular invasion around the appendiceal serosa. The tumor was composed of two main cell populations: mucin-producing (goblet cell type) and silver-positive cells (endocrine differentiation). Additionally, a few cells were also positive for serotonin and lysozyme, but negative for gastrin and ACTH. These findings suggest that goblet cell carcinoid share some functional and histologic characteristics with carcinoid tumors and adenocarcinomas, although it is a distinct entity.