C61-18 A Classic Presentation With a Rare Diagnosis: Follicular Bronchiolitis

Abstract Non-CF bronchiectasis can often present as a diagnostic challenge. The differentials could be broad with infection, primary immunodeficiency, aspiration and primary ciliary dyskinesia being the most common causes in children¹. We present the case of a pediatric patient who was referred to the primary ciliary dyskinesia (PCD) clinic for evaluation with symptoms of daily wet cough, chronic recurrent acute otitis media with effusion and wheezing since 5 months of age. Recurrent symptoms of cough and pulmonary exacerbations led to further diagnostic evaluation including immune work-up which was largely normal, PCD and CFTR genetic panel which revealed one heterozygous pathogenic variant (c.1210-34TG11T5) and variants of unknown significance for PCD (ANKZF1, ELANE, IRF8, NFAT5, NME8). Ciliary transmission electron microscopy showing normal ciliary ultrastructure. Serial CT of chest showed progressive bronchiectasis, tree in bud opacities along with hazy interstitial opacities consistent most likely with chronic infectious process. Flexible bronchoscopy showed normal anatomy and mucosa. The bronchoalveolar lavage studies were negative. Polysomnogram findings included moderate persistent hypoxemia without any evidence of sleep apnea. Her immune work up showed mild B cell abnormalities with low class switched memory B cells and plasmoblasts with elevated CX-CL9 levels. She had normal immunoglobulin levels including IgG, IgA and IgM along with normal vaccine responses. She was then started on airway clearance and prophylactic Bactrim which helped decrease the frequency of exacerbations. Given inability to arrive at a diagnosis, decision for lung biopsy was made and it revealed follicular bronchiolitis. She is currently undergoing therapy under the GLILD protocol. Our case highlights the significance of lung biopsy in the diagnosis of rare lymphoproliferative lung disorders. While our patient was very well compliant with medications and follow ups, the lag time to diagnosis appears to be inevitable². However, early diagnosis is paramount to help direct management and prevent long term lung impairment³. References 1. American Academy of Pediatrics, Section on Pediatric Pulmonology & Sleep Medicine. (2023). Pediatric Pulmonology (2nd ed.). American Academy of Pediatrics 2. Prenzel, Freerk et al. “Lymphocytic interstitial pneumonia and follicular bronchiolitis in children: A registry-based case series.” Pediatric pulmonology vol. 55,4 (2020): 909-917. doi:10.1002/ppul.24680 3. Tashtoush, Basheer et al. “Follicular Bronchiolitis: A Literature Review.” Journal of clinical and diagnostic research : JCDR vol. 9,9 (2015): OE01-5. doi:10.7860/JCDR/2015/13873.6496 This abstract is funded by: none