The most frequent neoplasm of the appendix in children is the carcinoid tumor, mostly a finding after appendicectomies due to acute appendicitis, and it is often located in the distal third of the organ. It arises from argentaffin cells of the epithelia. Macroscopically, these neoplasms are often yellow, firm, and almost always < 1 cm. Microscopically, cells are arranged in different patterns, often forming nests, and are separated by fibrous septa. Fine-needle aspirates show sheets and/or nests of midsize round uniform cells with eosinophilic cytoplasm and sometimes granular and round central hyperchromatic nuclei.
Key features of carcinoid tumor
|•||Sheets or nests of cells;|
|•||Round uniform cells; and|
|•||Granular (“salt and pepper”) nuclei.|