Epidermolysis Bullosa Acquisita Presenting With Usual Interstitial Pneumonia and Pneumomediastinum

Abstract

INTRODUCTION: Epidermolysis Bullosa Acquisita (EBA) is an autoimmune disease which presents with chronic blistering and scarring of the skin and mucous membranes. We present a case of EBA presenting with Usual Interstitial Pneumonia (UIP) and pneumomediastinum; an extremely rare complication. CASE PRESENTATION:An 84 year-old man presented to the emergency department with worsening dyspnea and multiple blistering lesions along with associated fatigue and weight loss for approximately 6 months. Past medical history was significant for previously diagnosed EBA, hypertension and hyperlipidemia. The patient is a Veteran and retired salesman who denied hazardous occupational exposure. Physical examination revealed bilaterally decreased breath sounds and also multiple crusted blisters in all four extremities. COVID test was negative and initial laboratory panel was only remarkable for mild macrocytic anemia. Outpatient chest radiograph obtained ten days prior to admission (fig 1) and repeat on admission showed bilateral interstitial reticulonodular opacities with new asymmetric opacifications in the right lung apex (fig 2). Chest CT angiogram demonstrated fibrotic changes and honeycombing in the peripheries and bases with moderate pneumomediastinum (fig 3). He was diagnosed with UIP given the radiologic pattern and this was attributed to be likely due to his current EBA flare-up given no other obvious trigger. The patient's home dose of dapsone for EBA was continued and he was given nebulized bronchodilators with improvement in his symptoms over 48 hours. Pulmonology was consulted and recommended outpatient follow up in 3 weeks as he remained hemodynamically stable and was saturating well on room air. Repeat Chest CT on follow up showed improvement of the pneumomediastinum (fig 4). Pulmonary function tests showed moderate restrictive lung disease with moderately reduced diffusing capacity, however his symptoms were mostly resolved.DISCUSSION: EBA is an orphan autoimmune whose pathophysiology involves auto-antibodies against type VII collagen (COL7). These create a specific u-serrated pattern on peri-lesional skin biopsies [1]. COL7 is also known to be a component of the pulmonary basement membrane; with collagen accounting for a third of the dry mass of the lung. EBA has been weakly associated with multiple autoimmune diseases including anecdotal reports of association with pulmonary fibrosis [2]. However extensive review of literature showed no published case reports connecting the two conditions. In our opinion, this patient's presentation is likely a result of the interaction of COL7 antibodies with the pulmonary basement membrane leading to UIP with pneumomediastinum.CONCLUSIONS: This case highlights the rare association between EBA and UIP which are likely connected pathophysiologically by anti-COL7 antibodies. Further research and analysis will be needed to confidently establish this association.