LAM cells generally expand interstitial spaces without violating tissue planes but have been observed to invade the airways, the pulmonary artery, the diaphragm, aorta, and retroperitoneal fat, to destroy bronchial cartilage and arteriolar walls, and to occlude the lumen of pulmonary arterioles.There are two major cell morphologies in the LAM lesion: small spindle-shaped cells and cuboidal epithelioid cells. LAM cells stain positively for smooth muscle actin, vimentin, desmin, and, often, estrogen and progesterone receptors. The cuboidal cells within LAM lesions also react with a monoclonal antibody called HMB-45, developed against the premelanosomal protein gp100, an enzyme in the melanogenesis pathway. This immunohistochemical marker is very useful diagnostically, because other smooth muscle–predominant lesions in the lung do not react with the antibody. The spindle-shaped cells of the LAM lesion are more frequently proliferating cell nuclear antigen positive than the cuboidal cells, consistent with a proliferative phenotype. Compared with cigar-shaped normal smooth muscle cells, spindle-shaped LAM cells contain less abundant cytoplasm and are less eosinophilic. Estrogen and progesterone receptors are also present in LAM lesions, but not in adjacent normal lung tissue. LAM lesions express lymphatic markers LYVE-1, PROX1, podoplanin and VEGFR-3. The smooth muscle–like cells of AMLs are morphologically and immunohistochemically similar to LAM cells, including reactivity with antibodies directed against actin, desmin, vimentin, and HMB-45 as well as estrogen and progesterone receptors. Unlike the dilated airspaces in emphysema, the cystic spaces found in LAM may be partially lined with hyperplastic type II cells.
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 Sjögrens syndrome. See also
PEComa

References
External links
American Thoracic Society (US): Patient Information Series – Lymphangioleiomyomatosis