Spontaneous pneumothorax with isolated pulmonary Langerhans cell histiocytosis in an adult case: A common manifestation of rare disease

KEY CLINICAL MESSAGE: Pulmonary Langerhans cell histiocytosis should be evaluated even in adults with no previous medical history and no history of cigarette smoking who have spontaneous pneumothorax and evidence of multiple lung cystic lesions, and other organs should also be checked for multi organ Langerhans cell histiocytosis involvement. ABSTRACT: A 30‐year‐old man presented with sudden chest pain and evidence of multiple cystic lesions in both upper and lower lobes of lungs, as well as left‐sided pneumothorax in high resolution computed tomography. In lung samples, hematoxylin and eosin‐ stained sections and IHC for CD1a, S100, and BRAF V600 were positive. The patient was diagnosed with isolated pulmonary Langerhans cell histiocytosis and was treated accordingly.