All Bite and No Bark: A Rare Case of Adult Croup Due to Influenza B

Abstract

SESSION TITLE: Other Infections SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: The incidence of adult croup is rare. Reported cases demonstrate variable presentations and severity, often prompting additional laboratory testing and imaging not routinely ordered in pediatric croup. We describe a unique case of croup in an elderly female with positive influenza B viral PCR testing and CT imaging that revealed subglottic narrowing consistent with laryngotracheobronchitis. CASE PRESENTATION: 89 year-old female presented with 2 days of sore throat, generalized malaise and non-productive cough. She was hemodynamically stable, temperature 101.1°F, respiratory rate 16bpm, and SpO2 88% on room air. Patient’s lungs were clear to auscultation without retractions, wheezes, or stridor. CBC and BMP were unremarkable. Rapid influenza A/B screen was negative. A neck x-ray revealed the characteristic “steeple sign” (fig. 1), which was re-demonstrated on neck CT showing moderate gradual subglottic narrowing consistent with laryngotracheobronchitis (fig. 2). Initial therapies included supplemental oxygen, IV dexamethasone, albuterol/ipratropium nebulizer and IV ceftriaxone. Viral PCR panel was positive for influenza B. Antibiotics and supplemental oxygen were subsequently discontinued and the patient improved clinically and was discharged home with close follow-up. DISCUSSION: Acute laryngotracheobronchitis, more commonly known as croup, is an upper respiratory illness of the pediatric population. Croup is typically a viral etiology, most often parainfluenza, respiratory syncytial virus, and influenza A/B. Traditionally, the diagnosis of pediatric croup is made clinically based on the presence of a hallmark barking cough and stridor; however, this was not the situation in the illustrated case and further imaging of the neck was required to confirm the diagnosis. The standard treatment for viral croup is supplemental oxygen, steroids, and inhaled racemic epinephrine. Close monitoring in an advanced care unit is recommended given the risk of acute respiratory failure. Positive direct viral antigen detection from nasal washings allows for cessation of antibiotics. This patient was outside the window to benefit from oseltamivir and demonstrated significant improvement following 24 hours of supportive therapy. CONCLUSIONS: There have been only 15 previously documented cases of adult croup. The presentation of laryngotracheobronchitis is insidious in adult patients that lack the hallmark barking cough or stridor of pediatric croup. Therefore, unlike the clinical diagnosis in children, the work-up in adults warrants supplementary laboratory testing and imaging to confirm the diagnosis of adult croup. Curative therapies are ultimately the same in both demographics. Reference #1: Woo PCY, et al. Adult Croup: A Rare but More Severe Condition. Respiration. 2000;67:684-688. Reference #2: Tong MCF, et al. Adult Croup. CHEST. 1996;109:1659-62. Reference #3: Patel JJ, et al. A Narrowing Diagnosis: A Rare Cause of Adult Croup and Literature Review. Case Reports in Critical Care. 2017;2017:9870762. DISCLOSURE: The following authors have nothing to disclose: Amy Stacey, Josh Erlandsen, Marc Raslich No Product/Research Disclosure Information