Spindle cell lipoma of the tongue: Two case reports

Spindle cell lipoma (SCL) is a rare tumor of soft tissues, and was first described in 1975 by Enzinger and Harvey SCL often occurs in elderly men as a solitary lesion in the posterior neck and back, and less commonly in the oral cavity. SCL of the tongue is relatively uncommon, and only 14 cases have been reported to date. Here, we describe two cases of SCL of the tongue. A 78-year-old male and a 77-year-old female were diagnosed with tongue tumors, and both underwent resection. Histopathological examination of the resected tumors revealed that they consisted of masses of mature fat cells with fibrous bundles accompanied by hyperplasia of spindle cells surrounding the adipose cells. Immunohistochemistry was performed for histological diagnosis. Using immunohistochemical staining, the spindle cells of each tumor were found to be positive for CD34 but negative for S-100. The nuclei of the spindle cells were negative for Rb and STAT6, and CDK4 and MDM2 immunostaining was negative in every tumor cell. In case 2, some spindle cells were positive for p16, but all were completely negative in case 1. Finally, these tumors were diagnosed as SCLs. To make a definitive pathological diagnosis for SCL, a panel of immunohistochemical markers incorporating CD34, S-100, STAT6, Rb, p16, MDM2 and CDK4 is required to avoid confusion with histologic mimics.