SESSION TITLE: ILD Student/Resident Case Report Posters
SESSION TYPE: Medical Student/Resident Case Report
PRESENTED ON: Tuesday, October 28, 2014 at 01:30 PM - 02:30 PM
INTRODUCTION: Birt-Hogg-Dubé syndrome is characterized by pulmonary cysts and recurrent pneumothorax. Whether these patients are prone to develop a pneumothorax in relation to changes in atmospheric pressure, for instance during air travel, has not been studied.
CASE PRESENTATION: Patient 1, a non-smoker, presented himself at the Emergency Department with increased shortness of breath after diving (maximal depth 5 meters) followed by a 3 hour flight home the next day. Chest X-ray showed left sided pneumothorax, which was treated with tube thoracostomy. Because of persistent air leak, he was treated with a total pleurectomy during VATS. Pneumothorax recurred 10 months later and was treated with chemical pleurodesis during thoracoscopy. A chest CT was performed, showing multiple cysts in the parenchyma and subpleural, below the level of the main carina. BHD was confirmed after genetic testing. Patient 2, diagnosed with BHD after presymptomatic testing, underwent partial bilateral apical pleurectomy 2 years ago after pneumothorax, because of an assumed increased risk for developing (recurrent) pneumothorax. After a flight from Europe to US, and ascending 110 stores (1,454 feet) the next day, he developed dyspnea. Chest X-ray showed collapse of the lower half of the left lung. Treatment is planned.
DISCUSSION: Accordingly to Boyle’s law, trapped gas in a closed volume will expand as pressure outside it decreases, this occurs when ascending from sea-level, for instance during air travel. We assume that this enlarges the cysts, which may lead to rupture of the cyst and subsequently development of pneumothorax.1 Detailed analysis of these cysts demonstrates no connection with the bronchial tree.2 Although the cellular and pathophysiologic mechanisms that lead to cystic lesions in BHD are not known, the defects in cell-cell adhesion in FLCN-deficient cells may underlie the pathogenesis of air-space enlargement in BHD. If the increased cell-cell adhesion of cells in an epithelial surface results in less potential to stretch, it might result in rupture at the weakest spot of a continuous surface if the stretching force is strong enough.3 Multiple lung cysts in the basal parts of the lung are characteristic for BHD. The areas in the lung where the largest stretching occurs are the lower parts of the lung. If pleurodesis is restricted to the upper part of the lung, the risk for developing pneumothorax in the area which is most likely to be the weakest (lower half) is not reduced. Patient 2 is an example of this.
CONCLUSIONS: Therefore prevention of BHD related pneumothorax is preferably done by pleurodesis of the complete lung. If this has not been done a patient with BHD and subpleural cysts is prone to develop pneumothorax if exposed to considerable atmospheric pressure changes.
Reference #1: Baumann MH. Chest, 2009; 136: 655
Reference #2: Kumasaka T et al. Histopathology 2014, Jan 7. [Epub ahead of print]
Reference #3: Medvetz DA et al. PlosOne 2012, Nov. e47842 [Epub ahead of print]
DISCLOSURE: The following authors have nothing to disclose: Paul Johannesma, Arjan Houweling, Marinus Paul, Tijmen van der Wel, Marianne Jonker, JanHein van Waesberghe, Jeroen Van Moorselaar, Fred Menko, Pieter Postmus
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