PEComatous tumors arise from perivascular epithelioid cells and can present in the lung in following forms: 1) Lymphangiomyomatosis; 2) Clear cell sugar tumor of lung; 3) PEComatosis – with overlapping features between lymphangiomyomatosis and PEComa. 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 genes TSC1 and TSC2). References:Goldblum, J.R., Folpe, A.L., Weiss, S.L. (2014). Enzinger & Weiss’s Soft Tissue Tumors, 6th Ed. Philadelphia, PA: Elsevier Saunders. Travis, W.D., et al. (2015). WHO Classification of Tumors of the Lung, Pleura, Thymus and Heart, 4th Ed. IARC: Lyon, France.