Original ArticlesComposite Intestinal Adenoma-MicrocarcinoidLin, Jingmei MD, PhD*,†; Goldblum, John R. MD†; Bennett, Ana E. MD†; Bronner, Mary P. MD‡; Liu, Xiuli MD, PhD†Author Information *Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN †Department of Anatomic Pathology, Cleveland Clinic, Cleveland, OH ‡Division of Anatomic Pathology, University of Utah, Salt Lake City, UT Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Jingmei Lin, MD, PhD, Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 350 West 11th Street, Indianapolis, IN (e-mail: email@example.com). The American Journal of Surgical Pathology: February 2012 - Volume 36 - Issue 2 - p 292-295 doi: 10.1097/PAS.0b013e318236e4d2 Buy SDC Metrics 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. © 2012 Lippincott Williams & Wilkins, Inc.