1271: MUCINOUS ADENOCARCINOMA MIMICKING INTERSTITIAL LUNG DISEASE DISCOVERED POST-TRANSPLANT

Abstract

Introduction: Mucinous adenocarcinomas typically present with cough, dyspnea and pleuritic chest pain. They have a wide range of radiographic appearances including a single nodule, lobar consolidation, or diffuse nodules. These tumors can mimic infectious and non-infectious pulmonary pathologies both clinically and radiographically. We report a rare case of invasive mucinous adenocarcinoma, mimicking interstitial lung disease discovered post bilateral lung transplant. Unfortunately, the diagnosis was made after lung transplantation posing a challenge in the management of immunosuppression in the setting of malignancy. Description: A 47-year old male with no prior medical history initially presented with progressive dyspnea on exertion for several months. Family history was significant for pulmonary fibrosis in his mother. High resolution CT chest showed extensive ground-glass opacification, upper lobe honeycombing, and consolidative changes with air bronchograms in bilateral lower lobes. Autoimmune workup and hypersensitivity pneumonitis panel were negative. Bronchoscopy and multiple sputum cultures were unrevealing. Genetic testing identified a mutation in the SFTPA2 gene, associated with familial pulmonary fibrosis. Patient’s respiratory status improved with intravenous steroids and he was discharged with oxygen supplementation, prednisone and nintedanib. However, patient was admitted two months later with clinical deterioration and acute hypoxemic respiratory failure requiring venovenous extracorporeal membrane oxygenation as a bridge to successful bilateral lung transplantation. A lung biopsy prior to transplant could not be obtained given the rapid progression of patient’s respiratory failure. Subsequently, pathology of the explanted lungs showed invasive mucinous adenocarcinoma with metastatic disease to a perihilar lymph node. PET CT scan was negative for extra thoracic metastasis. Discussion: After a multidisciplinary discussion, it was decided to continue immunosuppression with tacrolimus and a decreased dose of mycophenolate. Additionally, active surveillance with PET CT scans every three months was recommended. This case highlights the difficulties faced in the diagnosis of pulmonary adenocarcinoma due to its clinical and radiographic overlap with interstitial lung disease.