Diagnosis: tubular carcinoid of appendix and acute appendicitis.

Discussion: the remaining specimen was submitted into 20 additional cassettes, but no tumor was seen in these sections. The tumor is confined to the submucosa and superficial muscularis propria and present in only one section measuring 3.5 mm in maximum dimension. This tumor is a type of mixed exocrine-endocrine tumor of appendix which also includes goblet cell carcinoids and mixed carcinoid-adenocarcinoma. Histologically the tumor in this case shows no goblet cell differentiation and no classic adenocarcinoma features. It is composed of small glands and tubules interspersed amongst smooth muscle bundles of the appendiceal wall. No cytologic atypia (beyond typical neuroendocrine lesion) is seen. According to the literature (see reference) tubular carcinoids are behaving in a benign fashion.

Reference: Capella C et al. Endocrine tumours of the appendix. In Hamilton SR and Aaltonen LA (Editors): WHO Classification of Tumours. Pathology and Genetics Tumours of the Digestive System. IARC Press, Lyon 2000:99-101.