Lymphangioleiomyomatosis (LAM) occurs in at least 40% of women with tuberous sclerosis complex (TSC), as diagnosed based on chest CT scan findings. Early identification may inform lifestyle choices and treatment decisions. Here we report LAM prevalence in a large TSC clinic and propose an approach to CT scan screening for LAM in women with TSC.
We retrospectively reviewed initial chest CT scans of all female patients with TSC aged ≥ 15 years seen at our center over a 12-year period. Each CT image slice was manually scored for the presence or absence of characteristic thin-walled cysts, and the diagnosis of LAM was made if the sum of the cysts on all slices exceeded three cysts.
Of 133 female patients with TSC, 101 had chest CT scans available for review. Forty-eight (47.5%) met criteria for TSC-LAM on the initial CT scan. The risk of LAM was age dependent, rising by about 8% per year. The prevalence of LAM was 27% in subjects < 21 years of age and 81% in subjects > 40 years of age. Among asymptomatic subjects with LAM, 84% had cysts present in the single image at the level of the carina. Most subjects with LAM eventually developed pulmonary symptoms (63%), and 12.5% died from LAM.
These results suggest that most women with TSC ultimately develop cystic changes consistent with LAM and that most cases can be identified from a single CT imaging slice at the level of the carina. TSC-LAM was associated with appreciable morbidity and mortality in this referral population. An age-based approach using limited CT scanning methods may facilitate screening and subsequent treatment decisions with decreased radiation exposure in this at-risk population.