Histopathologic examination revealed a well-circumscribed subcutaneous tumor with a loose fibrous pseudocapsule. The tumor was composed of a mixture of smooth muscle, mature adipose tissue, and vascular spaces. The smooth muscle was arranged in fascicles that were intermingled with mature adipocytes or around vascular spaces in a way that resembled tunica muscularis. A stain for smooth muscle actin was positive. The vascular spaces were of various shapes and sizes and lined by endothelial cells. There was no evidence of mitotic figures or nuclear atypia in the tumor.
An Asymptomatic Preauricular Subcutaneous Nodule in a 65-Year-Old Woman—Diagnosis. Arch Dermatol. 2003;139(3):381-386. doi:10.1001/archderm.139.3.381-a