Atypical lipomatous tumors with smooth muscle differentiation: report of two cases

Two cases of soft-tissue atypical lipomatous tumors with areas of smooth mu scle cell differentiation are presented. The patients were a 72-year-old ma n (Case 1) and a 62-year-old woman (Case 2); their neoplasms were located i n the left inguinal region and on the chest, respectively. The adipocytic c omponent in Case 1 contained cells with nuclear atypism and lipoblasts. Cas e 2 showed only slight nuclear atypism and lacked any lipoblasts. Smooth mu scle fascicles were composed of well-differentiated cells with a few mitose s having none or only a slight atypism. They expressed muscle-specific acti n and desmin in both cases. No recurrence was recorded during the follow-up time.