ABSTRACT
Pulmonary lymphangioleiomyomatosis (or lymphangiomyomatosis) (LAM) is a
rare disease of women, which is characterized by smooth muscle cell infiltration
and cystic destruction of the lung and abdominal tumors including angiomyoli-
pomas (AMLs) and lymphangiomyomas (1-3). LAM typically results in progres-
sive dyspnea on exertion and recurrent pneumothoraces and is also occasionally
associated with chylous fluid collections in the chest and/or abdomen. LAM was
first described at autopsy in 1919, in a patient with tuberous sclerosis complex
(TSC), a genetic disorder of highly variable penetrance associated with seizures,
brain tumors, and cognitive impairment (4). For most of the 20th century, LAM
was thought to affect only a few percent of patients with TSC. However, recent
screening studies of women with TSC have revealed that about 30% to 40% have
cystic changes in the lung consistent with LAM (5-7), placing the predicted
number of patients with TSC-associated LAM (TSC-LAM) at about 200,000
worldwide. In 1937, in Germany, LAM was reported in a woman who did not have
TSC (8); a form of LAM that is now termed ‘‘sporadic LAM’’ or ‘‘S-LAM.’’ The
prevalence of S-LAM is difficult to determine, but registry data from various
countries suggest a minimum prevalence of about one to three cases per million
(9,10), or about 20,000 patients worldwide. For reasons that are not clear, S-LAM
patients outnumber TSC-LAM patients in the LAM Foundation Registry, The
National Heart, Lung and Blood Institute (NHLBI) Registry (11), and most pul-
monary clinics by a factor of 7 to 10 to 1, despite the 10-fold lower prevalence of
S-LAM. LAM has no clear ethnic or geographical predilection. It occurs pre-
dominantly in women between menarche and menopause, but it has been reported
in prepubescent girls (12) and female octogenarians (13). Radiographic evidence
of cystic lung disease has occasionally been described in men with TSC (14), but
biopsy-documented LAM has only been reported in four men, three with
TSC-LAM (15,16) and one with S-LAM (17).
