Ultrastructural observations in pleomorphic liposarcoma.

An ultrastructural study of pleomorphic liposarcoma with an unusual clinical presentation is described. A 69-year-old Caucasian female presented with recurrent superficial phlebitis of left leg, which responded only partially to conventional therapy. Following investigations, a mass was excised. Diagnosis of pleomorphic liposarcoma was made on microscopic examination. Numerous lipid droplets in the cytoplasm and often within intranuclear extensions of cytoplasm were seen on oil red O stain of frozen sections. Ultrastructural features are quite distinctive. The cells varied from small to often large pleomorphic cells with numerous lipid spaces without limiting membrane, large pleomorphic nuclei, and an abundance of cytoplasmic organelles. Centrioles were very prominent, in close proximity to nuclei, and collections of autophagocytic inclusions. Intercellular collagen was immature and scant. These features are compared to ultrastructural features of malignant fibrous histiocytoma, pleomorphic rhabdomyosarcoma, and cardiac myxoma, indicating that ultrastructural features are distinctive and help differentiate similar soft tissue tumors.