Spontaneous Rupture of the Tracheal Smooth Muscles.

SESSION TITLE: Bronchology/Interventional Procedures Cases IISESSION TYPE: Affiliate Case Report SlidePRESENTED ON: Monday, October 27, 2014 at 11:00 AM - 12:00 PMINTRODUCTION: Trachea is chondromembranous structure. Its posterior muscle fibers comprise of outer longitudinal and inner transvers fibers which extends between the ends of the cartilages. Severe atrophy and separation of the tracheal smooth muscles (TSM) from the cartilages is rare and hasn't being studies well. Herein we present a case of severe atrophy and separation of TSM from the cartilages in a COPD patient.CASE PRESENTATION: 62 year old female with very severe COPD (FEV1 16%) diagnosed in 2000, was referred for lung transplant evaluation. Treated with inhaled steroid, long acting beta agonist (LABA) and tiotropium bromide. Started on low dose systemic steroid since 2012. Left lung transplant was performed in Dec 2013 with fairly stable post-transplant course except for low grade rejection treated with pulse steroids. Post-transplant surveillance bronchoscopy revealed separation of tracheal muscles from cartilagenous rings supporting the notion of smooth muscle atrophy and possible rupture (Fig:1A & 1B). Her CT scan obtained during exhalation revealed near total collapse of the lower trachea further supporting the notion of the spontaneous rupture(Fig:2A & 2B).DISCUSSION: We believe that our patient developed atrophy of TSM with eventual separation from tracheal cartilages; the etiology of which is still unclear. Role of airway remodeling is poorly understood in COPD1 but airway dilation has been observed. Steroid and B2 agonist synergize to prevent airway smooth muscles proliferation2. Their continued use may induce muscle atrophy as reported by Fernandes et al with use of inhaled steroid3. Mounier Kuhn Syndrome is associated with atrophy of airway smooth muscles but no cases of spontaneous rupture have been reported. The exact cause and predisposing factors of TSM atrophy is unknown but important to recognize and needs further investigation.CONCLUSIONS: TSM atrophy is under reported. It could lead to spontaneous rupture and separation of the tracheal cartilages from posterior wall. Its important to recognize this entity while its etiology and management remain challenging.Reference #1: Jeffery PK. Structural and inflammatory changes in COPD: a comparison with asthma. Thorax. Feb 1998; 53(2): 129-136Reference #2: Dekkers BG et al. Glucocorticosteroids and β₂-adrenoceptor agonists synergize to inhibit airway smooth muscle remodeling. J Pharmacol Exp Ther. 2012 Sep;342(3):780Reference #3: Fernandes D et al. Anti-inflammatory steroids inhibit mitogen-induced proliferation of human cultured airway smooth muscle. Am J Respir Crit Care Med '95;4:A47DISCLOSURE: The following authors have nothing to disclose: Khawaja Zaki, Amit Banga, Thomas Gildea, Atul MehtaNo Product/Research Disclosure Information.