Isolated pulmonary Langerhans cell histiocytosis in a 10-month-old infant

Langerhans cell histiocytosis (LCH) is characterized by clonal proliferation and accumulation of abnormal dendritic (Langerhans) cells in various organs. Pulmonary involvement, although rare in children, has been reported in 20%-50% of childhood cases of multisystem LCH. Isolated pulmonary LCH in children, especially in infants, is still rarer, but should be suspected in those with cystic lung disease. We report a case of a 10-month-old boy who presented with chronic dyspnea and whose chest computed tomography (CT) scan demonstrated cystic lesions. Lung biopsy established the diagnosis of LCH; microscopy revealed a background of lymphocytes and eosinophils with kidney-shaped abnormal cells. These abnormal cells were positive for S-100, CD207 (Langerin), and CD1a on immunohistochemical staining. Chemotherapy was administered using a cytotoxic agent (vinblastine) and a steroid. After 12 weeks of induction chemotherapy, although no significant change in cyst size was noted on chest CT, clinical symptoms improved. Consolidation chemotherapy was then administered for 1 year. Thereafter, chest CT findings demonstrated a significant decrease in cyst size and a significant increase in the volume of normal lung parenchyma. Therefore, aggressive treatment of isolated pulmonary LCH in infants with severe tissue destruction and symptoms seems warranted.