Mucosa-associated lymphoid tissue (MALT) of the gallbladder: a clinicopathological correlation

Objective: Lymph follicles are frequently found on histological examination of a surgically removed gallbladder. The significance of these lymph folli cles is not clearly understood. The aim of this study was to examine the cl inicopathological correlation between the lymph follicles in the gallbladde r morphologically and the mucosa-associated lymphoid tissue (MALT) in the g ut. Methods: The gallbladders were fixed and cut serially. The tissue slices we re processed in the routine manner for a histological examination. The hist ological criteria for MALT in this study was defined as the presence of lym ph follicles with germinal centers in the lamina propria mucosae in approxi mately equal numbers in all portions of the gallbladders from the neck to t he fundus. Biliary bile obtained at surgery was cultured for a bacteriologi cal examination in the hospital laboratory. The types of gallstones were cl assified according to the Classification of Gallstones by the Japanese Soci ety of Gastroenterology. Results: Of the 1341 patients, 158 (11.8%) patients fulfilled the histologi cal criteria, including 64 men and 94 women with an average age of 64.2 yea rs. Gallstones were present in 89.2% of the patients, and 74.5% of these we re calcium bilirubinate gallstones. Cultures of the bile were positive in 9 5.4% of the patients. A variety of bacterial species were thus found, most commonly Escherichia coli and Klebsiella spp. Grossly, the gallbladders usu ally showed a granular appearance of the mucosa, Conclusion: The MALT in the gallbladder is not a rare condition and is freq uently encountered in clinical practice. This lymphoid tissue may represent a mucosal and morphological immune phenomenon for infection rather than a substrate for the development of low-grade B-cell lymphoma.