Individuals with pulmonary lymphangioleiomyomatosis develop severe destructive lung disease. Most of them are females of childbearing age. Currently, there is no proven effective therapy and the prognosis is variable. This study is designed to (a) define the clinical course of the disease and (b) elucidate the pathogenesis of the disease at the cellular and molecular levels, in order to develop more effective therapy. To accomplish this, we intend to identify the proteins and genes that contribute to the process of lung destruction in affected individuals.