Pulmonary Langerhans cell histiocytosis in a 26-year-old female: still a diagnostic challenge

Langerhans cell histiocytosis (LCH) is a rare disorder caused by monoclonal Langerhans cells proliferation in bone, skin, lung, lymph nodes, liver, spleen, nervous or hematopoietic system. Pulmonary LCH is a diagnostic trap that is displayed on computed tomography (CT) as an interstitial disorder with honeycomb aspect. In this paper, we present an unusual case of a 26-year-old female that was hospitalized with progressive worsening dyspnea and history of recurrent pneumonia. Lung biopsy showed fibrosis of the interalveolar septa, architectural distortion and large cells with foamy cytoplasm and convoluted nuclei that were marked by CD68, S-100 and the specific antibody CD1a that allowed establishing the diagnosis of pulmonary LCH. The only extrapulmonary manifestations were femoral bone cysts that were radiologically seen 10 years before and were not modified along the years. The therapy consisted on smoking cessation and oral corticosteroids without significant improvement of the clinical symptoms and enlargement of the cystic spaces during six months of follow-up. This case highlights for a rare disorder of the lung that should be taken into account in young patients with progressive pulmonary fibrosis.