Lymphangioleiomyomatosis (LAM) is a rare disease that affects young women of child-bearing age. It is characterized by the presence of cystic changes in the pulmonary parenchyma, repeated pneumothorax, chylothorax and renal angiomyolipomas, and in the majority of cases it is accompanied by a progressive loss in lung function.1 In the last two decades, there has been an increase in the understanding of LAM, both in its clinical as well as physiopathological aspects and molecular biology. The first case of sporadic LAM was published in 1937,2 but the first national registries were not initiated until the 1990s. In the year 2000, somatic mutations were reported in the genes of tuberous sclerosis (TSC2) in LAM patients.3 Since then, LAM research has grown exponentially, and recently the results have been published from a multicenter, randomized, placebo-controlled clinical assay with sirolimus in this disease.4 The true incidence and prevalence of LAM are unknown. In the United States, The LAM Foundation has 1300 registered patients. In Spain, in recent years the LAM registry has been begun through the Integrated Research Project (Proyecto de Investigacion integrada – PII) for Diffuse Interstitial Pulmonary Diseases (Enfermedades Pulmonares Intersticiales Difusas – EPID) of the Spanish Society of Pulmonology and Thoracic Surgery (Sociedad Espanola de Neumologia y Cirugia Toracica – SEPAR). To date, 72 cases have been included, which have been contributed by 23 centers in 8 autonomous Spanish communities (provinces).5 Due to its low prevalence, LAM is a disease that is rather unknown, even in the medical setting. Many of the symptoms of the disease (dyspnea, cough) are similar to those of other lung diseases, such as asthma or chronic bronchitis, which results in its late diagnosis. Lung transplantation is the best therapeutic option in the advanced phases of the disease.6 LAM treatment has been based on the use of therapies with anti-estrogenic effect, such as oophorectomy, progesterone, tamoxifen and gonadotropinreleasing hormone analogue. There are no placebo-controlled