Polypoid invasive carcinoma of the gallbladder-Another challenging polypoid neoplasm

Invasive gallbladder carcinoma generally presents as nodular-sclerosing growth. Recently, "polypoid invasive carcinoma (PICA)" showing grossly visible polypoid neoplasm and histologically invasive carcinoma with no adenomatous components was proposed as a neoplastic polyp of the gallbladder.

We herein report five cases of PICA collected from 49 cases of invasive gallbladder carcinoma in comparison with another polypoid preinvasive neoplasm of gallbladder, intracholecystic papillary neoplasm (ICPN).

Polypoid invasive carcinomas were composed of four males and one female with an average age of 74 years. Polypoid lesions were sessile (height ranging from 6 to 10 mm and the largest diameter ranging from 12 to 40 mm), and histologically, polypoid neoplasms presented papillary configuration containing tubular and cribriform components with thin inflammatory, fibrotic stroma. Polypoid carcinoma invaded directly and continuously into the gallbladder wall with destruction of the muscle layer. These patterns of PICA were different from ICPN, showing papillary patterns containing tubular components with fine fibrovascular stalks and with occasional focal stromal invasion but with preserved muscle layer. Post-operative outcome was not favorable in PICA but was favorable in ICPN.

Polypoid invasive carcinoma shared several pathological features with ICPN, such as intraluminal polypoid pattern with papillary configurations, but PICAs were invasive adenocarcinoma with destruction of muscle layer while ICPNs were preinvasive neoplasm with occasional focal stromal invasion, thus both should be differentiated from each other.