A case of spindle cell lipoma arising in the tongue

Spindle cell lipoma (SCL) is a distinct histological variant of lipoma, characterized by replacement of mature fat cells by collagen-forming spindle cells. We report a case of SCL that arose in the tongue of a 75-year-old Japanese man. Immunohistochemical analysis revealed that the spindle cells expressed CD34, bcl-2, and vimentin. Interestingly, the tumor cells exhibited strongly positive immunoreactivity for cyclin-dependent kinase 4 (CDK4). Since it has already been reported that CDK4 is not expressed in ordinary lipomas but expressed in almost all cases of liposarcoma, the positive immunoreactivity for CDK4 in the present case suggests that SCL has a character that is distinct from ordinary lipoma.