A78-24 The Great Imitator: Organizing Pneumonia

Abstract Introduction Organizing pneumonia (OP) is a rare inflammatory lung disease characterized by intra-alveolar buds of granulation tissue and variable interstitial inflammation. OP may be classified as cryptogenic (COP) or secondary to identifiable causes such as infections, medications, radiation, or systemic autoimmune disease. COP has an annual incidence of approximately 1.1 per 100,000 individuals, most commonly affecting middle-aged adults (50-60y), with male predominance, occurring equally in smokers and non-smokers. Clinical and radiologic findings can mimic other diagnosis, making histopathologic confirmation essential for accurate diagnosis. Description We present the case of a 69-year-old female with opioid use disorder, 40 pack-year smoking history, COPD (not on home O2), chronic back pain, prior DVT/PE, suprasellar mass, and anxiety who presented with worsening back pain after a mechanical fall. Trauma workup incidentally revealed a 6.3 cm mixed mass-like opacity with surrounding reticular opacities involving the entire right lung. Bronchoscopy with biopsy was performed and supported the diagnosis of OP. Ultimately, the patient demonstrated a favorable response to corticosteroid therapy, shown by improvement of radiological findings on discharge. This case underscores the diagnostic challenge of OP especially in this patient’s atypical clinical presentation. Discussion In this case, OP was shown to be a diagnosis of exclusion due to its nonspecific symptoms and overlapping radiologic findings of other pathologies. The typical signs and symptoms of OP include subacute respiratory symptoms such as cough and/or dyspnea. However, this patient’s chief complaint was back pain- highly atypical for OP. Objectively, CT imaging revealed a 6.3 cm mixed attenuation mass-like opacity with surrounding reticular opacities involving all the lobes of the right lung and a moderate pleural effusion, highly suggestive of malignancy. Further workup with biopsy identified presence of Masson bodies. The atypical disease pattern seen in this patient’s case of OP, their risk factors and pre-existing lung disease highlight that OP can present in various ways. After diagnosis, the etiology of OP was investigated to determine secondary causes vs cryptogenic OP. This abstract is funded by: None