Pulmonary Langerhans cell histiocytosis: evolution of lesions on CT scans.

PURPOSE: To document the evolution of pulmonary lesions of Langerhans cell histiocytosis (LCH) with sequential computed tomography (CT).

MATERIALS AND METHODS: Initial and final CT scans of 21 patients with LCH and CT evidence of pulmonary disease were compared retrospectively. Histologic confirmation of pulmonary involvement was available in 11 patients.

RESULTS: On initial CT images, a nodular pattern (n = 14) was seen more frequently than a cystic pattern (n = 7). On final CT images, a cystic pattern (n = 14) was seen more often than a nodular one (n = 6). There was complete resolution of parenchymal abnormality in one case. Nodular opacities, thick-walled cysts, and ground-glass opacities underwent regression. Thin-walled cysts, linear opacities, and emphysematous lesions remained unchanged or progressed.

CONCLUSION: Pulmonary CT allows good assessment of the evolution of LCH lesions. Nodular lesions probably represent active disease and often undergo regression or transform into cysts.