Adult Pulmonary Langerhans Cell Histiocytosis with Osseous Involvement: understanding this rare mimic of malignancy

Langerhans cells are dendritic cells that form the antigenic barrier of the human body. They occur in nearly any tissue but are most prevalent in the skin, submucosa of the bronchial tree, and other mucosae. Langerhans Cell Histiocytosis (LCH) develops when these cells damage the tissues in which they reside through a combination of inflammatory and monoclonal stimulation. The pulmonary variant of LCH involves the lung parenchyma and creates many disturbances, including pulmonary hypertension and obstructive and restrictive lung disease. Osseous involvement, in addition to the pulmonary variant, presents with pulmonary masses and lytic bone lesions, which sparks suspicion for malignancy. Early recognition of this rare pathology is important as early treatment is clinically beneficial. The following explores a case of adult Pulmonary Langerhans Cell Histiocytosis with osseous involvement.