Original ArticlesNon-neoplastic Polyps of the Gallbladder A Clinicopathologic Analysis of 447 CasesTaskin, Orhun C. MD*; Bellolio, Enrique MD†; Dursun, Nevra MD‡; Seven, Ipek Erbarut MD§; Roa, Juan C. MD∥; Araya, Juan C. MD¶; Villaseca, Miguel MD†; Tapia, Oscar MD∥; Vance, Courtney MD#; Saka, Burcu MD**; Balci, Serdar MD#; Bagci, Pelin MD§; Losada, Hector MD††; Sarmiento, Juan MD‡‡; Memis, Bahar MD#; Pehlivanoğlu, Burcin MD#; Basturk, Olca MD§§; Reid, Michelle D. MD, MSc#; Koshiol, Jill PhD∥∥,§§; Cheng, Jeanette D. MD¶¶; Kapran, Yersu MD*; Adsay, Volkan MD*Author Information *Department of Pathology, Koç University Hospital ‡Department of Pathology, Istanbul Research and Training Hospital §Department of Pathology, Marmara University Pendik Research and Training Hospital **Department of Pathology, Medipol University, Istanbul, Turkey Departments of †Anatomic Pathology ††Surgery and Traumatology, Universidad de La Frontera ¶Department of Pathology, Hospital Dr. Hernan Henriquez Aravena, Temuco ∥Department of Pathology, Pontificia Universidad Catolica de Chile, Santiago, Chile Departments of #Pathology ‡‡Surgery, Emory University School of Medicine ¶¶Department of Pathology, Piedmont Hospital, Atlanta, GA §§Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY ∥∥Infections and Immunoepidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD O.C.T. and E.B. are cocontributing first authors. Present address: Bahar Memis, MD, SBU Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey. 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: Volkan Adsay, MD, Department of Pathology, Koç University Hospital, Davutpasa Caddesi No: 4, Topkapi, Istanbul 34010, Turkey (e-mail: [email protected]). The American Journal of Surgical Pathology: April 2020 - Volume 44 - Issue 4 - p 467-476 doi: 10.1097/PAS.0000000000001405 Buy Metrics Abstract There is no systematic histopathologic analysis of non-neoplastic polyps in the gallbladder. In this study, in addition to a computer search for cases designated as “polyp,” a systematic review of 2533 consecutive routinely sampled archival and 203 totally submitted prospective cholecystectomies were analyzed for >2 mm polyps (cut-off was based on radiologic sensitivity). A total of 447 non-neoplastic polyps were identified. The frequency was 3% in archival cases and 5% in totally submitted cases. Only 21 (5%) were ≥1 cm. The average age was 52 years, and the female to male ratio was 3.1. Two distinct categories were delineated: (1) injury-related polyps (n=273): (a) Fibro(myo)glandular polyps (n=214) were small (mean=0.4 cm), broad-based, often multiple (45%), almost always (98%) gallstone-associated, and were composed of a mixture of (myo)fibroblastic tissue/lobular glandular units with chronic cholecystitis. Dysplasia seen in 9% seemed to be secondary involvement. (b) Metaplastic pyloric glands forming polypoid collections (n=42). (c) Inflammatory-type polyps associated with acute/subacute injury (11 granulation tissue, 3 xanthogranulomatous, 3 lymphoid). (2) Cholesterol polyps (n=174) occurred in uninjured gallbladders, revealing a very thin stalk, edematous cores devoid of glands but with cholesterol-laden macrophages in 85%, and cholesterolosis in the uninvolved mucosa in 60%. Focal low-grade dysplasia was seen in 3%, always confined to the polyp, unaccompanied by carcinoma. In conclusion, non-neoplastic polyps are seen in 3% of cholecystectomies and are often small. Injury-related fibromyoglandular polyps are the most common. Cholesterol polyps have distinctive cauliflower architecture, often in a background of uninjured gallbladders with cholesterolosis and may lack the cholesterol-laden macrophages in the polyp itself. Although dysplastic changes can involve non-neoplastic polyps, they do not seem to be the cause of invasive carcinoma by themselves. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.