Cindy McGrath

1 Introduction Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms characterized by epithelioid to spindled cells arranged in a perivascular pattern, coexpressing melanocytic (e.g., HMB-45, Melan-A) and smooth muscle (e.g., actin, desmin) markers [1-9]. Related tumors include angiomyolipomas, lymphangioleiomyomatosis, and clear cell “sugar” tumors, and are often associated with tuberous sclerosis complex (TSC) [1-5, 7-11].