We describe a 2 ½ year old boy presenting with fever, abdominal pain and splinter haemorrhages of the nails. On further examination there were signs of pneumonia with pleural effusion. This was treated with mini-thoracotomy, drainage and intravenous antibiotics. Further diagnostic workup for underlying causes showed diffuse cystic lung disease, suggestive of Langerhans cell histiocytosis. This was confirmed on pathology specimens, which showed Langerhans cells in lung tissue, nail bed and skin biopsy samples, indicating multisystem Langerhans cell histiocytosis. The patient was treated with Prednisone and Vinblastin according to the LCH-III guidelines. In this case report we give a brief description on cystic lung disease in children, Langerhans cell histiocytosis and associated nail abnormalities.