PULMONARY LANGERHANS CELL HISTIOCYTOSIS DESPITE SMOKING CESSATION

Abstract

SESSION TITLE: Diffuse Lung Disease 1 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 pm - 02:15 pm INTRODUCTION: Pulmonary Langerhans’ cell histiocytosis (PLCH) is a diffuse lung disease that mainly affects young adult smokers (ages 20-40). The pathology may involve an over-reactive inflammatory response to inhaled irritants (i.e. smoke). With chronic inflammation, Langerhans cells migrate into the interstitium of small airways, forming peribronchiolar nodules and later cystic lesions. Patients remain asymptomatic or commonly present with cough, dyspnea, or pneumothorax. Constitutional symptoms (fever, sweats, weight loss) and chest pain may also be seen. CT chest classically reveals nodules and thin- or thick-walled, irregular cystic lesions in the middle and upper lungs with bibasilar and costophrenic angle sparing. This unique CT pattern has a high diagnostic accuracy in young smokers and precludes the need to biopsy, especially if therapy is limited. Smoking cessation is the mainstay of treatment, and may lead to radiological resolution. CASE PRESENTATION: A previously asymptomatic 57-year-old Lebanese male with a past medical history of hypertension presented with 3 days of severe, right pleuritic chest pain and dyspnea. He denied cough, hemoptysis, wheezing, fever, chills, weight loss, or chest trauma. Physical exam, labwork, and EKG were unremarkable. Chest X-ray showed diffuse cystic changes. Chest CT with contrast revealed multiple nodules and irregular, thin-walled cysts principally in the upper and middle lung zones, consistent with PLCH. No pleural involvement was noted. The patient had a 30 pack-year history of smoking tobacco, but quit around 18 years prior to admission due to persistent cough, malaise, and night sweats. He rarely smokes hookah. Bronchoscopy with bronchoalveolar lavage was unremarkable (confirms the diagnosis in only 10 to 50% of cases). Bone scan ruled out lytic lesions in his chest and body. He improved symptomatically, and declined further workup (PET scan and video assisted thoracoscopic surgery). DISCUSSION: A strong association exists between smoking and PLCH, but the precise relationship between the two has not been clearly delineated. Only a fraction of smokers develop PLCH, and PLCH has also been noted in nonsmokers, suggesting host factors or a ‘second hit’ may be responsible for pathogenesis. Nevertheless, smoking cessation is the mainstay of treatment in most patients. Yet despite smoking cessation, the disease course of PLCH is variable and unpredictable. While some patients have partial or complete remission or stabilization, others have progression to end stage fibrocystic changes and pulmonary failure. In this patient, PLCH was atypically diagnosed 18 years after smoking cessation. CONCLUSIONS: PLCH should be considered in any past or current smoker when imaging shows nodules and cysts in the upper and middle lungs. More studies are warranted to examine how smoking and other exogenous or host factors alter the causation, progression, and prognosis of PLCH. Reference #1: Tazi A. Adult pulmonary Langerhans' cell histiocytosis. The European respiratory journal. Jun 2006;27(6):1272-1285. Reference #2: Suri HS, Yi ES, Nowakowski GS, Vassallo R. Pulmonary langerhans cell histiocytosis. Orphanet journal of rare diseases. Mar 19 2012;7:16. Reference #3: Colby TV, Lombard C. Histiocytosis X in the lung. Human pathology. Oct 1983;14(10):847-856. DISCLOSURES: No relevant relationships by Amir Al-Dabagh, source=Web Response No relevant relationships by Bishr Aldabagh, source=Web Response No relevant relationships by Siddique Chaudhary, source=Web Response No relevant relationships by John Youssef, source=Web Response