Primary mucosa-associated lymphoid tissue (MALT) lymphoma of the gallbladder and review of the literature.

Mucosa-associated lymphoid tissue (MALT) lymphoma is rarely observed in the gallbladder, and its diagnosis before surgery is difficult. This report describes a case of primary MALT lymphoma of the gallbladder in an 80-year-old man. Imaging studies revealed a protruding lesion on the inside of the gallbladder, which led us to diagnose gallbladder carcinoma prior to the patient undergoing extended cholecystectomy. Microscopic examination of the resected specimen of the gallbladder demonstrated lymphoid follicles with atypical lymphocytes and the formation of lymphoepithelial lesions. These findings led to a final pathological diagnosis of primary MALT lymphoma of the gallbladder. The patient has been free of recurrence for 39 months after the surgery. Although precise diagnosis before the surgery was difficult in this case, preoperative examinations revealed a submucosal tumour-like lesion. MALT lymphomas should be considered when imaging findings are atypical for gallbladder carcinoma.