A80-3-37 What Lies Beneath Cryptogenic Organizing Pneumonia: A Case Report

Abstract Introduction Cryptogenic organizing pneumonia (COP) is an idiopathic interstitial lung disease (ILD) characterized by alveolar injury and organization, typically presenting in the fifth or sixth decade of life with subacute onset of fever, malaise, dyspnea, and cough. Diagnosis requires exclusion of secondary causes such as medications, autoimmunity, infection, and malignancy. However, certain malignancies, including metastatic pancreatic adenocarcinoma, may exhibit lepidic growth patterns that mimic ILD radiographically and histologically, posing significant diagnostic challenges and treatment delay. Here, we present a rare case of metastatic pancreatic adenocarcinoma initially manifesting with features consistent with COP. Case Description A 58-year-old female with a history of chronic obstructive pulmonary disease and parrot exposure, presented with cough, shortness of breath, and chest tightness. On admission, she required up to 15 L/min of oxygen via high-flow nasal cannula, compared to her baseline of 5 L/min via nasal cannula. She had experienced similar symptoms in the past and reported a gradual decline. Initial imaging showed a few scattered nodular opacities, which progressively developed into patchy ground-glass opacities with central consolidative components. Transbronchial biopsies of the right upper lobe revealed lung parenchyma with intra-alveolar macrophages, findings consistent with COP. There were also focal CD1a-positive cells, suggestive of pulmonary Langerhans cell histiocytosis. However, given her worsening symptoms despite corticosteroid treatment and removal of her parrot, a surgical biopsy was performed. Repeat pathology with immunoprofiling was suggestive of metastatic pancreatic adenocarcinoma. Discussion This case highlights the limitations to transbronchial lung biopsy in excluding malignancy, especially for small 2 cm, peripherally located with a negative bronchus sign. A negative biopsy should not outweigh clinical judgement, especially when patients continue to deteriorate despite appropriate therapy. Although earlier surgical biopsy may not have altered this patient’s outcome due to poor prognosis of pancreatic adenocarcinoma with distant metastasis, timely escalation could be critical in less aggressive malignancies. This report also underscores that a diagnosis of COP should prompt consideration of secondary causes when there is no clinical or radiologic improvement after corticosteroid therapy. This abstract is funded by: None