The occurrence of liposarcoma in the tongue is rare with only 34 cases published so far. We report six new cases of atypical lipomatous tumor (ALT) of the tongue, and detection of mdm-2 and CDK4 expression by immunohistochemistry and fluorescence in situ hybridization (FISH), respectively, was performed. The series comprised three males and three females, aged 11-78 years. The tumors arose at the lateral side of the tongue, and in one case, multiple tumor nodules were noted. Follow-up information in five cases (range from 4 to 159 months) revealed one local recurrence at 6 months. Microscopically, four cases had features of lipoma-like ALT, whereas two cases displayed patterns of sclerosing ALT. Immunohistochemically, tumor cells revealed expression of vimentin (five of five), S100 (five of five), mdm-2 (three of five), and CDK4 (four of five). Two cases were also examined by FISH; amplification of mdm-2 gene was found in both cases, whereas amplification of CDK4 gene was present in one case only. To the best of our knowledge, this is the third largest series reporting occurrence of ALT in the tongue and the first one where analysis of mdm-2 and CDK4 proteins/genes expression/amplification was performed. Both these markers may be of help in the differential diagnosis of ALT versus lipoma. Although most ALTs of the tongue behave in the nonaggressive fashion, they may recur locally. Based on current data, the term ALT is strongly recommended for tumors occurring in the tongue to prevent inadequate treatment.

The Fingerland Department of Pathology Charles University Medical Faculty and Faculty Hospital in Hradec Kralove Hradec Kralove Czech Republic

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