β-Catenin is a useful adjunct immunohistochemical marker for the diagnosis of pulmonary lymphangioleiomyomatosis.

Lymphangioleiomyomatosis (LAM) is a rare multisystem disease leading to cystic destruction of the lung parenchyma and is associated with abnormal smooth muscle proliferation affecting airways, lymphatics, and blood vessels. LAM occurs sporadically or in association with the tuberous sclerosis complex (TSC). Recent evidence demonstrates the role of aberrant β-catenin signaling in TSC. To further understand the pathogenesis of LAM and to examine the diagnostic usefulness of β-catenin, we examined protein expression in 28 pulmonary LAM cases and 10 cases of renal angiomyolipoma resected from patients with sporadic LAM. Immunohistochemical analysis was performed for established markers of LAM cells (HMB45, estrogen receptor [ER]-α, and progesterone receptor [PR]) and β-catenin. All LAM cases were positive for β-catenin and demonstrated high specificity with overall immunoreactivity superior to HMB45, ER-α, and PR. Similar expression was demonstrated in renal angiomyolipoma. Our results indicate that β-catenin is a useful marker of LAM and may be clinically useful in the diagnostic setting.