A Case of Pulmonary Langerhans' Cell Histiocytosis Mimicking Hematogenous Pulmonary Metastases

A 31-year-old man presented with a dry cough and exertional dyspnea. The chest X-ray showed multiple nodular opacities throughout the entire lung field. Chest computed tomography (CT) revealed variable-sized nodules with a peribronchiolar or centrilobular distribution, some of which revealed thick-walled cavitary change. Based on the chest CT findings, it was initially assumed that metastatic lung nodules with hematogenous spread were present; therefore, we performed an open lung biopsy. On microscopic examination, several compact cellular interstitial infiltrates composed of Langerhans' cells, eosinophils, and lymphocytes were observed. Immunochemically, the Langerhans' cells showed strong cytoplasmic staining for S-100 protein. Based on these findings, the patient was diagnosed with Langerhans' cell histiocytosis of the lung. High-resolution CT of the chest is a useful, sensitive tool in the diagnosis of pulmonary Langerhans' cell histiocytosis (PLCH). A typical radiologic finding of PLCH is irregularly shaped cysts. The radiological finding in this case of nodular opacities throughout the lung fields only without cysts is rare in PLCH. We report a case of PLCH with atypical multiple nodules mimicking hematogenous metastatic lung nodules.