Langerhans cell histiocytosis presenting as uncontrolled asthma

Langerhans cell histiocytosis (LCH) is an uncommon disorder affecting primarily young adult smokers. It is characterized by abnormal proliferation of Langerhans cells, specialized monocyte-macrophage lineage antigen-presenting cells. LCH can affect the lungs in isolation or as part of a systemic disease. Most commonly, the disease presents in the third or fourth decade without gender predominance. Symptoms typically include dyspnea and cough. Commonly, physical examination is unremarkable but cor pulmonale may be observed in advanced disease. The chest radiograph is typically abnormal with nodular or interstitial infiltrates and cystic changes. High-resolution computed tomography of the chest with these findings in the middle and upper lobes of an adult smoker is virtually diagnostic of LCH. Pulmonary function assessment is variable. Asthma has rarely been reported in association with this disorder. There are only three reported cases of the diagnosis of concomitant asthma which have been made in association with the diagnosis of LCH. We present a case in which our patient presented with signs and symptoms of asthma to include confirmatory findings of airway hyperresponsiveness. The diagnosis of LCH was established after the patient failed to respond to conventional treatment for asthma, and further evaluation was completed.