SESSION TITLE: Wednesday Fellows Case Report Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Usual interstitial pneumonia (UIP) is a common radiographic pattern seen in interstitial lung disease, and is traditionally required for the diagnosis of Idiopathic pulmonary fibrosis (IPF). In older adults without clinical suspicion for other forms of interstitial lung disease, IPF diagnosis does not require BAL when UIP is present. In probable UIP, expert recommendations on the utility of BAL are conflicting. We present a patient with probable UIP on High resolution CT (HRCT), favorable clinical features for ILD, and negative serologies, who was diagnosed with chronic eosinophilic pneumonia after BAL. CASE PRESENTATION: This is 69 year old male with a past medical history of HTN, HLD, GERD, and a remote history of bladder cancer status post local resection. Over the past 1.5 years, he had been seen in our clinic for dyspnea, with a decline in functional status. His FVC was now moderately severe, with a reduced DLCO. His HRCT of the chest was consistent with probable UIP, and had progressed. He had recently begun home oxygen therapy, was referred for pulmonary rehabilitation, and had started pirfenidone. Multidisciplinary discussion with an advanced lung disease center was pursued. He had no systemic signs or symptoms of other causes of interstitial lung disease. He had not started any other new medications and was a life-long non-smoker. The only other finding was a low level peripheral eosinophilia. He underwent Bronchoscopy and BAL, which showed a 19% eosinophilic predominance, but with a low total yield. The BAL was repeated 4 months later, and now showed a 35% eosinophilic predominance. Plans were made to start him on prednisone therapy, and he has shown steady improvement since that time. DISCUSSION: IPF is the most common etiology for new UIP in the over 60 population. The association is strong enough, that the 2018 ATS executive summary on diagnosis of IPF recommends against performing BAL in UIP cases with a strong clinical picture for IPF and negative serologies. This recommendation was based on potential risks of bronchoscopy for IPF patients, and a small chance of revealing meaningful diagnostic information. In probable UIP, BAL is recommended but overall evidence is remarked to be weak. Occasionally more prognostically favorable forms of ILD may appear similar, and diagnostic clues to prompt BAL may be subtle or absent. Functional status prior to diagnosis is an important consideration, since these patients have the most to gain when other etiologies are revealed. CONCLUSIONS: UIP is most likely to be IPF in the correct clinical setting. However, thresholds for pursuing BAL and cellular fluid analysis that include features other than clinical status and radiographic pattern may prevent underdiagnoses of more treatable forms of ILD. Previous functional status and comorbidities should be factored into this decision as well. Reference #1: Raghu et al., "Diagnosis of Idiopathic Pulmonary Fibrosis: An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline." ATS Documents, 2018 Reference #2: Cottin et al., "Eosinophilic Lung Diseases." Clin Chest Med. Sep, 2016. Reference #3: Oyama et al., "Efficacy of Short-Term Prednisone Treatment in Patients with Chronic Eosinophilic Pneumonia." Eur Respir J. JUN, 2015. DISCLOSURES: My spouse/partner as a Employee No relevant relationships by Jason Unger, source=Web Response