Multisystem Langerhans cell Histiocytosis presenting with spontaneous pneumothorax in a toddler: case report and literature review

Multisystem Langerhans cell histiocytosis (MS-LCH) is exceedingly rare in very young children and can present with predominant lung involvement. We report a 2-year-old boy who presented with prolonged fever, cough, and acute respiratory distress. Chest imaging revealed recurrent bilateral pneumothoraces requiring multiple chest drains; high-resolution computed tomography showed diffuse bilateral thin-walled lung cysts. Thoracoscopic lung biopsy with immunohistochemistry (CD1a+, CD45+, S100+) confirmed Langerhans cell histiocytosis. Given the strong association between pediatric pulmonary LCH and multisystem disease, a whole-body FDG-PET/CT was performed, revealing hepatic and splenic involvement and confirming a diagnosis of MS-LCH. Systemic chemotherapy with vinblastine and corticosteroids led to clinical improvement. We also review nine similar pediatric cases reported in the literature, highlighting the importance of recognizing pulmonary findings as a gateway to diagnosing underlying multisystem LCH.