IDIOPATHIC LARYNOTRACHEAL STENOSIS AND LOW ALPHA-ONE ANTITRYPSIN LEVELS

Abstract

SESSION TITLE: Tuesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM INTRODUCTION: Idiopathic laryngotracheal stenosis (ILS) is an inflammatory condition resulting in the narrowing of the airway. (1) To date, in the literature, there has been no clear association between ILS and low alpha-one antitrypsin (A1AT) levels. We report a case in which a patient had both abnormalities and we postulate mechanisms through which low A1AT levels could cause airway stenosis. CASE PRESENTATION: A 57-year-old lady with a past medical history of Parkinson's disease was sent for a second opinion for shortness of breath and wheezing. She had been erroneously diagnosed with A1AT deficiency and was started on augmentation therapy. Physical examination demonstrated a hoarse voice and diffuse expiratory wheeze, but no stridor, emanating from the upper airway. Her A1AT level was 79 mg/dl (normal 80-220 mg/dl) and her A1AT phenotype was PI*MZ. Pulmonary function testing showed the following: FVC: 87%, FEV1: 82%, FEV1/FVC: 93% and DLCO: 91%. The flow-volume loop suggested a fixed airway obstruction. Chest and neck tomography showed a scant amount of secretions involving the superior aspect of the trachea inferior to the vocal cord. She underwent bronchoscopy, which revealed tracheal narrowing to 5mm in diameter approximately 3 cm below the vocal cords. There was a thick fibrous band on the left side and a few smaller webs tethering the trachea. There was also a tracheal diverticulum present on the left side of the thick fibrous band. The rest of the tracheobronchial tree was normal. Initially, endobronchial scissors and a YAG laser were used to cut the webs and the trachea partially unfolded. The trachea was then dilated from 10 to 15 mm in diameter. Complete tracheal patency was achieved. DISCUSSION: ILS is rare and is most commonly seen in post-menopausal women. Proposed mechanisms are related to estrogen, disruption of blood supply, gastroesophageal reflux, and unremitting cough. (2) Secondary causes of laryngotracheal stenosis include prolonged endotracheal intubation and autoimmune diseases such as granulomatosis with polyangiitis and sarcoidosis. (1) There is no clear evidence showing an association between low A1AT levels and ILS. A1AT is a potent inhibitor of proteases and is crucial in conserving the integrity of connective tissue. In patients with low A1AT levels, these proteolytic enzymes can lead to fibrosis and scarring. Though most commonly associated with emphysema, low levels of A1AT have also been associated with arterial fibromuscular dysplasia with evidence of altered extracellular matrix and connective tissue abnormalities. (3) Although causation is impossible to establish in this case, we speculate that low A1AT levels may have led to connective tissue dysregulation and stenotic lesions of the trachea. CONCLUSIONS: This case is the first report of ILS occurring in the setting of low levels of A1AT. We speculate that there may be a pathobiologic link between the two entities. Reference #1: Gelbard A, Francis DO, Sandulache VC, Simmons JC, Donovan DT, Ongkasuwan J. Causes and consequences of adult laryngotracheal stenosis.Laryngoscope.2015 May;125(5):1137-43. https://doi.org/10.1002/lary.24956. Epub 2014 Oct 7. Reference #2: Damrose EJ. On the development of idiopathic subglottic stenosis. Med Hypotheses. 2008;71(1):122-5. https://doi.org/10.1016/j.mehy.2007.12.017. Epub 2008 Mar 4. Reference #3: Schievink WI, Björnsson J, Parisi JE, Prakash UB. Arterial fibromuscular dysplasia associated with severe alpha 1-antitrypsin deficiency. Mayo Clin Proc. 1994 Nov;69(11):1040-3. DISCLOSURES: No relevant relationships by Hamzah Alfahel, source=Web Response No relevant relationships by Anthony Cucci, source=Web Response No relevant relationships by Ahmad JABRI, source=Web Response No relevant relationships by Sanjiv Tewari, source=Web Response No relevant relationships by Elizabeth Verghese, source=Web Response