reported in some men with tuberous sclerosis, very few of these men develop symptoms. the prevalence of lam is estimated using data from registries and patient groups and is between 3.4 and 7.8/million women. the number of new cases each year is between 0.23 and 0.31/million women/year in the us, uk and switzerland. the variation between countries and between adjacent states in the us, suggest that a significant number of women with lam remain either undiagnosed or their symptoms are attributed to other diseases. adult women with tuberous sclerosis are more likely to develop lam than women without tuberous sclerosis. cohorts of patients with tuberous sclerosis have been screened for lam using ct scanning. in a retrospective study of adults with tuberous sclerosis, ct demonstrated lung cysts in 42% of 95 women and 13% of 91 men. in general, lung cysts were larger and more numerous in women than in men. in a further retrospective study of women with tsc who underwent ct scanning to detect lam, 25% of those in their 20s had lung cysts whereas 80% of women in their 40s were affected, suggesting that the development of lam is age dependent at least in tuberous sclerosis-related lam. although the prevalence of tuberous sclerosis at 1 in 6,000 births is much greater than that of lam, most pulmonary clinics see more cases of sporadic than tuberous sclerosis–lam: probably due to a combination of low levels of screening for lam in tuberous sclerosis and in many, the absence of symptoms. female sex and tuberous sclerosis are the only known risk factors. although use of supplemental estrogen is not associated with development of lam, one study suggested that use of estrogen-containing contraceptive pills was associated with earlier onset. it occurs in more than 30% of women with tuberous sclerosis complex (tsc-lam), a heritable syndrome that is associated with seizures, cognitive impairment and benign tumors in multiple tissues. most lam patients who present for medical evaluation have the sporadic form of the disease (s-lam), however, which is not associated with other manifestations of tuberous sclerosis complex. mild cystic changes consistent with lam have been described in 10–15% of men with tsc, but symptomatic lam in males is rare. sporadic lam occurs exclusively in women, with one published exception to date. both tsc-lam and s-lam are associated with mutations in tuberous sclerosis genes. pregnancy pregnancy has been reported to exacerbate lam in some cases. however, the risk has not been rigorously studied. in a survey of 318 patients who indicated that they had had at least one pregnancy, 163 responded to a second survey focusing on lung collapse. a total of 38 patients reported a pneumothorax with pregnancy, consistent with an incidence of pneumothorax in pregnancy of at least 10% (38 of 318). in one third of patients, the pneumothorax during pregnancy led to the lam diagnosis. pneumothoraces were almost twice as frequent on the right as on the left, and four women presented with bilateral spontaneous pneumothorax. most pneumothoraces took place during the second and third trimesters. this study and others suggest that pregnancy is associated with pleural complications in lam patients. few women with a known lam diagnosis choose to become pregnant and patients in whom lam is diagnosed during pregnancy rarely have baseline pulmonary function tests available, complicating resolution of this question. society the lam foundation was founded in 1995 as a grassroots organization to provide patient advocacy and research funding. today, the lam foundation provides support and education for women with lam and their families, engages doctors and scientists to continue to learn more about the disease, and raises funds for the continued study of lam. it seeks safe and effective treatments, and ultimately a cure, for lymphangioleiomyomatosis. it is headquartered in cincinnati, ohio. in popular culture in "lucky thirteen", the fifth episode of the fifth season of house, spencer (angela gots) was diagnosed with lam, though later it was found to be a case of sjögren's syndrome.