Lymphangioleiomyomatosis (LAM) is a rare lung disease that affects almost exclusively women. It was first described in the medical literature by von Stossel in 1937. The disease is characterized by an unusual type of muscle cell that invades the tissue of the lungs, including the airways, and blood and lymph vessels. Over time, these muscle cells form into bundles and grow into the walls of the airways, and blood and lymph vessels, causing them to become obstructed.

Although these cells are not considered cancerous, they grow without the usual controls within the lungs. Over time, the muscle cells block the flow of air, blood, and lymph vessels to and from the lungs, preventing the lungs from providing oxygen to the rest of the body.

An unusual, frequently asymptomatic, kidney tumor called Angiomyolipoma is found in up to 50% of patients with LAM.

About 2.5% of patients with tuberous sclerosis, a genetic disorder, develop a lung disease that is identical to that which occurs in LAM. These patients often have angiomyolipomas of the kidney as well. Although patients with LAM do not develop the central nervous system and skin changes of tuberous sclerosis, the similarities in the lung and kidney manifestations of the two diseases have led some investigators to postulate that they may have common causes. For more information contact the Tuberous Sclerosis Alliance.

Lymphangioleiomyomatosis is pronounced lim-fan je-o-lio-mi o-ma-to sis. Lymph and angio refer to the lymph and blood vessels. Leiomyomatosis refers to the formation of the bundles of the unusual muscle cells.

The cause of LAM is not known.