MALT lymphoma at the base of the tongue developing without any background of immunodeficiency or autoimmune disease.

We report a very rare case of a mucosa-associated lymphoid tissue (MALT) lymphoma of the base of the tongue. A 61-year-old woman was admitted to our hospital for further examination of a 12 mm x 15 mm x 5 mm tongue tumor. Histological examination of the tumor revealed a marked lymphoepithelial lesion. Lymphoma cells expressed CD5(-), CD10(-), CD19(+), CD20(+) on the surface of the cells by fluorescence activated cell sorter, and the genotypic analysis of the tumor cells revealed the presence of immunoglobulin heavy chain rearrangement and the absence of BCL-2 gene rearrangement by southern blot hybridization. Furthermore, neither the t(11;18) (q21;q21) translocation nor trisomy 3 was detected in lymphoma cells by fluorescence in situ hybridization method. The tongue tumor was completely resected and no recurrence has been noted in the 13 months to date.