Pathological classification of gallbladder polyps

Abstract

Gallbladder polyps are classified pathologically as either non-neoplastic or neoplastic. The majority of non-neoplastic polyps are cholesterol polyps, which are also termed hyperplastic polyps or fibrous polyps when the epithelium proliferates and the stroma becomes fibrotic in addition to a decrease of foam cells. Polyps that arise in the setting of inflammations include granulation tissue polyp, fibromyoglandular polyps and lymphoid polyps. Fibromyoglandular polyps are diagnosed as hyperplastic polyps, metaplastic polyps and fibrous polyps depending on findings in the epithelium or stroma. Neoplastic polyps include pyloric gland adenoma and intracytic papillary neoplasms (ICPN). Pyloric gland adenoma shows unique morphological features, and preferencially occurs in the gallbladder. ICPN was reported as a counterpart of pancreatic intraductal papillary mucinous neoplasms (IPMN) in the gallbladder, but the histological findings of ICPN are different from those of IPMN, and may also encompass lesions termed polypoid gallbladder carcinomas.