WHERE THERE IS NOT SMOKE THERE IS STILL FIRE: A CASE OF PULMONARY LANGERHANS CELL HISTOICYTOSIS IN A FORMER SMOKER WITH A HISTORY OF MULTIPLE MALIGNANCIES

Abstract

SESSION TITLE: Diffuse Lung Diseases SESSION TYPE: Fellow Case Reports PRESENTED ON: 10/22/2019 3:45 PM - 4:45 PM INTRODUCTION: Pulmonary langerhans cell histiocytosis (PLCH) is a cystic interstitial lung disease (ILD) that occurs almost exclusively in smokers. We present a case of PLCH in a former smoker with a history of multiple previous non-pulmonary malignancies. CASE PRESENTATION: A 71 year old African American female presented to us for management of multiple pulmonary nodules discovered on a PET/CT scan done for malignancy monitoring. CT chest showed multiple areas of reticulo-nodular densities with few cysts in bilateral upper lobe. She noted only cough and dyspnea on moderate exertion. No other organs were noted to be PET-avid. She has a history of stage I breast cancer status post bilateral mastectomy, stage II adenocarcinoma of the colon status post right hemicolectomy, and was a previous 1 pack per day smoker quiting in 1998. This was confirmed on urine and saliva testing for nicotine and cotinine. CT-guided transthoracic fine needle aspiration was suggestive of PLCH but subsequent trans-bronchial biopsy was non diagnostic. The time since she quit smoking cast doubt on her diagnosis, so a video assisted thoracoscopic lung biopsy was performed to evaluate for malignancies. Pathology revealed langerhans cells that stained positive for S-100 and CD1a. Given her history of previous malignancies and lack of current smoking, genetic analysis was done revealing a B-RAFV600E mutation. Her symptoms and pulmonary function tests declined, and she was started on supplemental oxygen. She did not respond to oral corticosteroids. She was referred to hematology and started on Dabrafenib, a B-RAF inhibitor. At her three month follow up visit, the patient noted improvement of her dyspnea, cough, and a decrease in her supplemental oxygen requirement. DISCUSSION: PLCH occurs almost exclusively in current and former smokers and the mainstay of treatment is smoking cessation, though immunosuppression is sometimes used. The lag time between cessation and development of disease has not been quantified. Recently, B-RAFV600E mutations have been identified in LCH and in several cases of PLCH. LCH, though more common in children, can occur in adults before, during, or after other malignancies, but is rarely limited to the lungs. In patients with progressive disease despite removal of smoke exposure, cladiribine, a purine analogue cytotoxic to lymphocytes, has been used to some success. The discovery of the B-RAFV600E mutation has also opened the door to treatment with BRAF inhibitors, such as in our patient. CONCLUSIONS: This case highlights the development of PLCH in a patient who has not smoked in 10 years, but has had multiple prior malignancies putting her at risk for the development of LCH. The presence of the B-RAFV600E mutation should be evaluated in patients with PLCH and LCH, as it represents a possible treatment for those who are not smoking and those whose disease progresses despite standard therapy. Reference #1: Roden, A., Yi, E.S. Pulmonary Langerhans Cell Histiocytosis: An update from the pathologist’s perspective. Arch Pathol Lab Med. 2016 Mar;140(3):230-40. DISCLOSURES: No relevant relationships by Scott Blumhof, source=Web Response No relevant relationships by Kevin Dsouza, source=Web Response No relevant relationships by Tejaswini Kulkarni, source=Web Response No relevant relationships by Amitkumar Mehta, source=Web Response