Incipient stage of pulmonary Langerhans-cell histiocytosis complicated with pulmonary tuberculosis was examined by high-resolution computed tomography.

A 29-year-old man with a smoking history of 20 pack years was diagnosed with tuberculosis because Mycobacterium tuberculosis was detected in his gastric juice. His chest radiograph showed multiple nodular opacities on left upper lobe. He was treated with anti-tuberculosis drugs in our hospital. Six months after the therapy, he began to complain of dry cough and shortness of breath on exertion. Chest radiograph showed reticular opacities in both upper and middle lung fields. Multiple thick- and thin-walled bizarre-shaped cysts and ill-defined centrilobular opacities were seen mainly in upper and mid-lungs on high-resolution computed tomography (HRCT). He was diagnosed with pulmonary Langerhans-cell histiocytosis (PLCH) by transbronchial lung biopsy specimens from right upper lobe. HRCT findings before the treatment of tuberculosis were retrospectively examined. Several small thin-walled centrilobular cysts were scattered in the right upper and middle lung fields without apparent nodular lesions. We must consider the possibility of PLCH when these findings are detected on HRCT.