Pulmonary Langerhans Cell Histiocytosis

Background: Langerhans cell histiocytosis, a rare disease that occurs mainly in children, may present with a broad range of manifestations, from a single osseous lesion to multiple lesions involving more than one organ or system. The clinical course varies widely according to the patient’s age. Multisystem disease may show particularly aggressive behavior in very young children, with the outcome largely depending on the disease stage and the degree of organ dysfunction at the time of diagnosis. Extraosseous manifestations are less common than osseous ones and may be more challenging to identify. To accurately detect extraosseous Langerhans cell histiocytosis at an early stage, radiologists must recognize the significance of specific clinical and laboratory findings, as well as the relevance of imaging features for the differential diagnosis. The pattern and severity of pulmonary, thymic, hepatobiliary, splenic, gastrointestinal, neurologic, mucocutaneous, soft-tissue (head and neck), and salivary gland involvement in Langerhans cell histiocytosis are generally well depicted with conventional radiography, ultrasonography, computed tomography, and magnetic resonance imaging. However, imaging features are not pathognomonic, and biopsy is usually required to establish a definitive diagnosis. Keywords: Langerhans cell histiocytosis,