SESSION TITLE: Medical Student/Resident Diffuse Lung Disease SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Sarcoidosis is protean in its presenting characteristics. The most common pulmonary manifestations are hilar adenopathy and interstitial infiltrates. The alveolar filling pattern is noted less frequently. Here we present of a case of 53-year-old woman who was diagnosed with alveolar sarcoidosis after an incidental finding on chest X-ray. CASE PRESENTATION: A 53-year-old woman was admitted to hospital for sepsis secondary to a urinary tract infection after presenting with fever, malaise and low abdominal pain. She had a 20-pack-year smoking history. On physical exam the chest was clear to auscultation. A routine chest X-ray (fig 1) showed an ill-defined density to the left hemithorax. She reported no cough, SOB, hemoptysis or other respiratory symptoms. CT chest showed a 2.9cm ground glass opacity in the superior segment of the left lower lobe (fig 2). Given the patient’s smoking history, suspicion was high for malignancy. A CT guided transthoracic needle biopsy was done which showed non-caseating granulomata and no evidence of malignancy. Tissue smears were negative for bacteria, AFB and fungi, antigen tests for histoplasma and blastomyces were negative. ACE levels were elevated at 89U/L. A CT scan done 8 weeks following initial imaging showed complete resolution of the left lower lobe opacity (fig 3). PET scan done at that time showed no areas of increased uptake. DISCUSSION: The diagnosis of sarcoidosis depends on clinical and radiological characteristics, the presence of non-caseating granulomas and excluding alternate diagnoses. The pattern of alveolar infiltrate noted in this case is a rare presentation seen in ∼1.8% of cases. Biopsy confirmed the presence of non-caseating granulomata, and infection and malignancy were ruled out. Supporting evidence was given by the elevated ACE levels, which, while not sensitive for sarcoidosis, have been reported having ∼89% specificity. Bronchoscopy, which can support diagnosis with an elevated CD4/CD8 ratio was deemed unnecessary as the patient had no pulmonary symptoms and the diagnosis was already confirmed. PET scanning, which has been useful in the monitoring of sarcoidosis was done at follow up to evaluate for other potential sites of active disease, but none were found. In the majority of cases, the inflammatory lesions of sarcoidosis resolve spontaneously, often in under 2 years. The 8-week interval to resolution appears unusually quick, however the initial time of onset of the lesion was not known. This case illustrates an unusual presentation of sarcoidosis and serves as reminder that this diagnosis must be kept in mind when evaluating asymptomatic lung masses. CONCLUSIONS: As sarcoidosis is variable in its presentation, a clinician must be aware of atypical presentations including the pattern of alveolar infiltrates on imaging, which can be asymptomatic. Reference #1: Valeyre D, Prasse A, Nunes H, Uzunhan Y, Brillet PY, Müller-quernheim J. Sarcoidosis. Lancet. 2014;383(9923):1155-67 Reference #2: Vettiyil B, Gupta N, Kumar R. Positron emission tomography imaging in sarcoidosis. World J Nucl Med. 2013;12(3):82-6 Reference #3: Ungprasert P, Carmona EM, Crowson CS, Matteson EL. Diagnostic Utility of Angiotensin-Converting Enzyme in Sarcoidosis: A Population-Based Study. Lung. 2016;194(1):91-5 DISCLOSURES: No relevant relationships by Muhammad Faiz, source=Web Response No relevant relationships by Jovan Gayle, source=Web Response No relevant relationships by Somshukla Ghosh, source=Web Response No relevant relationships by Natarajan Rajagopalan, source=Web Response