BIRT-HOGG-DUBE: A RARE CAUSE OF SPONTANEOUS PNEUMOTHORAX

Abstract

SESSION TITLE: Medical Student/Resident Diffuse Lung Disease SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Birt-Hogg-Dube syndrome (BHDS) is a rare autosomal dominant disorder caused by mutations in the FLCN tumor suppressor gene responsible for the protein folliculin. BHDS is characterized by the clinical triad of early-onset upper body-predominant skin manifestations (58-90%), followed by the development of cystic lung lesions (67-90%), and, less commonly, renal cell carcinoma (30%). Here, we outline a common clinical presentation leading to the unexpected diagnosis of this rare genetic disorder. CASE PRESENTATION: A 54-year-old man with hypertension and a 30-pack-year smoking history presented with seven days of left upper abdominal pain. He described pain worse with deep inspiration and positional change and associated with nausea. He denied fevers, chills, shortness of breath and lower GI symptoms. Vital signs were normal with an oxygen saturation of 98% on room air. Physical exam showed normal respiration without use of accessory muscles. Palpation of the chest and abdomen was without tenderness. Auscultation demonstrated absent breath sounds at the left apex. Skin exam revealed multiple dome-shaped papules of the bilateral nasolabial folds and forehead. Comprehensive metabolic panel, troponin and complete blood count were all within normal limits. Chest radiography revealed a 1.2cm left apical-predominant pneumothorax, which was further evaluated with computed tomography (CT) of the chest. CT imaging confirmed the left apical pneumothorax and revealed a small, right, posterior pneumothorax. Additionally, multiple thin-walled lentiform cysts of various sizes were noted in all lung fields with subpleural and paramediastinal predominant locations and involving the costophrenic angles. The patient was admitted for monitoring and safely discharged the next day after improvement in symptoms and decreased size of his pneumothorax. The patient mentioned a significant lung disease history in his father and a brother with similar cutaneous abnormalities on his face. This family history and the patient’s skin and thoracic imaging findings aroused suspicion for BHDS. Additional lab testing returned positive for mutation in the FLCN gene, confirming the diagnosis. DISCUSSION: This case illustrates an acute presentation of secondary spontaneous pneumothorax due to BHDS. CT imaging is crucial in the work-up of spontaneous pneumothorax to determine the underlying etiology. In the setting of newly identified cystic lung disease on imaging, family history and thorough physical exam are essential in guiding clinicians to the diagnosis. CONCLUSIONS: Early diagnosis of BHDS is paramount, as additional work-up includes screening for renal cell cancer and cutaneous malignancies, as well as extensive genetic counseling. Reference #1: Gupta N, Vassallo R, Wikenheiser-Brokamp KA. Diffuse cystic lung disease part II. Am J Respir Crit Care. 2015; 192(1): 17-29. Reference #2: Jensen DK, Villumsen A, Skytte AB, Madsen MG, Sommerlund M, Bendstrup E. Birt-Hogg-Dube syndrome: a case report and review of the literature. Euvorpean Clinical Respiratory Journal. 2017; 4(1). Reference #3: Schmidt LS, Linehan WM. FLCN: the causative gene for Birt-Hogg-Dube syndrome. Gene. 2018; 640:28-42. DISCLOSURES: No relevant relationships by Alisha Kabadi, source=Web Response No relevant relationships by Judd Landsberg, source=Web Response No relevant relationships by William McGuire, source=Web Response