Pleomorphic Lipoma Masquerading as Malignant Neoplasm

Pleomorphic lipoma is a relatively rare adipocytic neoplasm, occurring predominantly in elderly males in the subcutaneous tissues of the neck or shoulder. It is considered as a variant of lipoma. Histologically, pleomorphic lipoma consists of varying quantity of mature fat, bland spindle cells and ropey collagen. In addition, it is characterized by multinucleate giant cells, which possess floret-like nuclei and marked pleomorphism. Here, we report a case of 51 year male presented with swelling over left arm since two years progressively increased in size. On cytology, a diagnosis of malignant neoplasm was made. Excised specimen was sent for histopathological examination and was diagnosed as pleomorphic lipoma based on the presence of mature adipose tissue, floret-like cells, spindle cells and absent mitotic figures. Because of the relative rarity, variable histological spectrum and cellular pleomorphism, pleomorphic lipoma is misdiagnosed easily. To avoid this misdiagnosis, careful attention should be paid to the above histopathological features.