P373 : A case of low-fat, fibrous spindle cell lipoma on the face

Spindle cell lipoma classically occurs as a solitary, subcutaneous, circumscribed lesion in the posterior back, neck, or shoulders of older men. Histologically, classic spindle cell lipoma is variably composed of ropey collagen, myxoid stroma, CD34-positive spindled cells, and mature fat. The variable proportion of these elements among different cases of the neoplasm makes diagnosis difficult. Herein, a 53-year old man presented for several years with an asymptomatic 2cm sized subcutaneous mass on left periauricular area. Skin biopsy specimen revealed prominent collagen bundles and focal myxoid stroma with mixed spindle cells and mature adipocytes which was noted to be present in ＜5% of the tumor. Immunohistochemical studies showed that spindle cells are positively stained with CD34 and myxoid stroma is positively stained with alcian-blue pH 2.5. We concluded that this is consistent with low-fat, fibrous variant of spindle cell lipoma.