Patients with tuberous sclerosis 18 years and older may enroll in this study. Participants will undergo a medical history and thorough skin examination by a dermatologist. Those with skin tumors will be asked to undergo biopsy (tissue removal) of up to eight lesions, under a local anesthetic, for research purposes. The biopsies will all be done the same day. The tissue samples will be used for: examination of genetic changes, measurement of certain proteins and other substances, and growing in culture to study the genetics of tuberous sclerosis.