We describe a case of pulmonary Langerhans cell histiocytosis with a close temporal relationship between smoking cessation and radiological improvement. High-resolution computed tomography revealed multiple small nodules located in the upper and middle lobes of both lungs. Microscopy of these lesions showed histiocytic infiltration that reacted strongly to staining for S100 protein. The histiocytes resembling Langerhans cells showed strong reactivity for S100 protein. Smoking cessation was recommended and the patient complied. Chest X-ray and computed tomography performed 6 and 24 months later revealed almost complete resolution of the radiographic abnormalities. Despite the possibility that this evolution was attributable to spontaneous remission, in this case, the lesions did, in fact, disappear rapidly after smoking cessation.

Keywords: Key words: Histiocytosis. Langerhans-Cell. Tabaco use cessation.