A 50–year–old Caucasian female with no prior respiratory ailments presented with worsening non productive cough and exertional dyspnea for 4 months. She denied fevers, weight loss or lower extremity swelling. She reported an 18 pack year history of ongoing smoking. She was prescribed multiple courses of antibiotics, oral steroids and bronchodilators with no subjective improvement. In fact, her cough worsened to a point where she sustained bilateral rib fractures after a coughing spell. Her physical exam was unremarkable. Chest CT revealed lower rib fractures, hyperinflation and bilateral pulmonary nodules measuring up to 5 mm. A comprehensive autoimmune, allergic and infectious workup that included bronchoscopy failed to identify an etiology of her interstitial lung disease. Differential diagnosis included sarcoidosis, lymphangiomatosis, eosinophilic pneumonia and diffuse metastasis. She subsequently underwent an open lung biopsy, which showed multiple stellate nodules that were S–100 protein–positive and CD–68–positive diagnostic of Langerhans Cell Histiocytosis. At this point, she was strongly recommended to quit smoking. On a follow up visit at 6 months, she denies any cough and dyspnea markedly improved.
Pulmonary Langerhans Cell Histiocytosis (PLCH) is a rare interstitial lung disease occurring exclusively in young cigarette smokers. The extremely low incidence and non–specific presentation often poses a diagnostic challenge to clinicians. Pulmonary LCH belongs to a spectrum of diseases characterized by the proliferation of specific histiocytes, known as Langerhans cells, and their infiltration of organs. An ongoing debate exists over whether LCH is a reactive or neoplastic process. Its association with smoking has been well described and it is now classified under smoking related interstitial lung diseases. Patients typically present with chronic non productive cough, dyspnea or spontaneous pneumothorax. Extra pulmonary manifestations including cystic bone lesions and diabetes insipidus have been described. In our patient, it is unclear whether rib fractures represent a purely mechanical complication versus extra–pulmonary involvement. Radiological appearance is typical with nodular opacities and interstitial fibrosis on a HRCT; however, most patients require a surgical biopsy for confirmation. Smoking cessation is the cornerstone of management. Clinical stabilization and often radiological resolution have been reported following smoking cessation. Steroids and chemotherapy have been tried in refractory cases. Long term complications include pulmonary hypertension and respiratory failure.
Physicians should consider PLCH in the differential of interstitial lung disease in young smokers. Early diagnosis is important because the clinical course of the disease may be dramatically altered by a single intervention, i.e., smoking cessation.