title: Composite intestinal adenoma-microcarcinoid.
abstract: Composite intestinal adenoma and microcarcinoid is a rare intestinal neoplasm consisting of intermingled adenomatous and well-differentiated neuroendocrine components. A few case reports and small series have suggested an indolent clinical course for this entity. We reported 7 cases of composite intestinal adenoma-microcarcinoid, including their morphologic features and clinical follow-up, both in biopsy and resection specimens. We identified 7 cases of composite intestinal adenoma-microcarcinoid from our pathology database. Five were from the large intestine, and 2 were in the duodenum. Morphologically, all microcarcinoids exhibited low-grade cytologic atypia and were devoid of significant pleomorphism, necrosis, and mitotic activity. Among the 7 lesions, 6 had a lobular architecture with smooth borders and mucosa-confined microcarcinoids; none had neuroendocrine carcinoma in subsequent resections. However, 1 colonic case had carcinoid cells penetrating the muscularis mucosae into the submucosa with an infiltrative border, and the resection showed metastatic high-grade neuroendocrine carcinoma in 1 lymph node. Composite intestinal adenoma-microcarcinoid is extremely rare. Although composite mucosa-confined adenoma-microcarcinoid is likely to have an indolent behavior, submucosal invasion by the neuroendocrine component may be associated with aggressive behavior.
authors.affiliation: Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. jinglin@iupui.edu
authors.forename: Jingmei
authors.initials: J
authors.lastname: Lin
authors.forename: John R
authors.initials: JR
authors.lastname: Goldblum
authors.forename: Ana E
authors.initials: AE
authors.lastname: Bennett
authors.forename: Mary P
authors.initials: MP
authors.lastname: Bronner
authors.forename: Xiuli
authors.initials: X
authors.lastname: Liu
mesh_terms: D000236:Adenoma / Q000473:pathology*; D000368:Aged; D002276:Carcinoid Tumor / Q000473:pathology*; D005260:Female; D006801:Humans; D007414:Intestinal Neoplasms / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000473:pathology*; D012189:Retrospective Studies