Clinical, tomographic, and functional comparison of sporadic and associated tuberous sclerosis complex forms of LAM: a retrospective cohort study

Lymphangioleiomyomatosis (LAM) is a rare disease that can occur sporadically (S-LAM) or associated with the tuberous sclerosis complex (TSC-LAM). The natural history of LAM is not completely understood, including whether there is a difference between the clinical courses of the two forms. This study aimed to compare the clinical, functional, and tomographic features between S-LAM and TSC-LAM, and evaluate the annual rates of change in lung function.This retrospective cohort study included patients with LAM followed up between 1994 and 2019. Clinical, functional and imaging variables were evaluated, and the lung cysts were automatically quantified. Quality of life and predictors of lung function impairment were accessed, and the annual rate of lung function decline was compared between S-LAM and TSC-LAM.Of the 107 patients included, 77 had S-LAM and 30 had TSC-LAM. Although patients with TSC-LAM had a higher prevalence of renal angiomyolipomas and neurological and dermatological manifestations, pulmonary function tests were similar. Patients with S-LAM had a greater rate of FEV1decline and a higher extent of cysts. Pneumothorax, desaturation in the six-minute walking test and a higher extent of lung cysts were predictors of functional impairment. A greater impact on vitality and emotional health was observed in the TSC-LAM.Greater functional decline and a higher cystic extension were found in patients with S-LAM. Our study provides a broad clinical, functional, and tomographic characterisation of patients with LAM, adding valuable information to the existing evidence to better understand the two forms of the disease.