High resolution chest computed tomography responses for a cohort of adult with pulmonary Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is a heterogeneous histiocytosis with various pulmonary manifestations and imaging. We aim to evaluate the pulmonary response of LCH by high resolution chest computed tomography (HRCT) through continuous follow-up.We conducted a retrospective analysis of 73 adult LCH patients with pulmonary involvement. HRCT response was assessed by the change of HRCT global score (nodule score plus cyst score) between the baseline and after therapy. Among them, 69 patients (94.5%) had multi-system LCH with pulmonary involvement. 42 patients received methotrexate and cytarabine regimen, 15 received cytarabine monotherapy, 7 underwent target therapy. 14 (19.2%) achieved complete response (CR) and 45 (61.6%) achieved partial response (PR). The mean global lung-lesion score decreased from 12.2 to 10.6. The mean nodule score decreased from 4.7 to 4.1 and the mean cyst score decreased from 7.4 to 6.5. Overall, 25 (34.2%) exhibited an HRCT response and 3 (4.1%) had HRCT progression, while 45 (61.6%) maintained the same. Among patients with CR or PR, 57.1% and 40.5%, respectively, experienced an HRCT response, whereas no patient with SD or PD had an HRCT response. Multivariable analyses revealed that patients who received low dose cytarabine regimen and those with HRCT score ≥ 10 predicted a shorter PFS. Long Chang, Luo Wang, and Zheng-zheng Liu contributed equally to this work.