This CT scan of lungs is from a 40 y/o female with tuberous sclerosis complex. The image demonstrates innumerable small regular lung cysts diffusely distributed throughout the lungs, the typical appearance of lymphangiomyomatosis (LAM). The patient also had a fat containing tumor within the kidney, most likely an angiomyolipoma. MRI of the brain showed cortical/subcortical tubers and supependymal nodules characteristic of tuberous sclerosis. Case courtesy of Dr. Charlie Chia-Tsong Hsu, Radiopaedia.org. From the case rID: 20712 PEComatous Tumors & Tuberous Sclerosis: Lymphangiomyomatosis, clear cell sugar tumor of lung (PEComa) and pecomatosis belong to the PEComatous family of tumors. Other tumors in this family include renal and extrarenal angiomyolipoma, primary extrapulmonary sugar tumor, clear cell myomelanocytic tumor, and abdominopelvic sarcoma of perivascular epithelioid cells. PEComatous tumors arise in a variety of sites and are tied together through their association with the tuberous sclerosis complex (and the mutations in tuberous sclerosis gene TSC2). About 1% of patients with tuberous sclerosis have changes in their lungs that are similar to LAM. About 15% of patients with LAM have tuberous sclerosis.