A large fibrous polyp of the gallbladder mimicking a polypoid carcinoma

Fibrous polyp of the gallbladder is a rare variant of benign gallbladder polyp. Differentiation between a benign polyp and polypoid carcinoma of the gallbladder is often difficult when the polyp is more than 1 cm in diameter. We report a rare case of a large fibrous polyp of the gallbladder mimicking a carcinoma. A 44-year-old Korean woman who presented with abdominal pain was diagnosed with a large gallbladder polyp, measuring 1.26 cm in diameter, by abdominal ultrasonography. The lesion was echogenic with a nodular surface on ultrasonography, and showed contrast enhancement on computed tomography. Neither evidence of infiltration into the gallbladder wall nor lymph node enlargement was shown. The resecte gallbladder showed a 1.2 × 0.8-cm-sized polyp with a nodular surface. Histologically, it showed a leaf-like configuration and loose or cellular connective stroma containing scattered duct-like structures, varying-sized vessels, and patchy infiltration of chronic inflammatory cells. Stromal cells were immunoreactive for vimentin and smooth-muscle actin and negative for S-100 protein and desmin. Large fibrous polyps of the gallbladder should be considered in the differential diagnosis of benign and malignant polypoid lesions of the gallbladder.