A hitherto undescribed benign mesenchymal polyp of the gallbladder: edematous angiomyolipoma-like polyp.

We report a case of two peculiar gallbladder polyps in a sixty-four year old male who presented with symptomatic cholelithiasis. Cholecystectomy was performed, which revealed two polyps measuring 0.6 cm and 1.9 cm, located in the body of the gallbladder. Microscopic examination of the polyps showed composite mesenchymal lesions with vascular proliferation of small-to-medium sized arterioles, myoid stroma, and lipomatous periphery. The myoid component was characterized by wisps of bland smooth muscle fibers loosely separated by proteinaceous and focally myxoid matrix. The surface of the polyps was lined by a single layer of bland epithelial cells. The unique histomorphologic features differentiate the lesions from other known mesenchymal polyps of the gallbladder. We propose the name "edematous angiomyolipoma-like polyp" for these rare lesions given their histomorphologic similarity to angiomyolipoma. (Acta gastroenterol. belg., 2016, 79, 371-374).