From Mimic to Diagnosis: Primary Lung Adenocarcinoma Presenting as Peripheral Airspace Opacities Mimicking Organizing Pneumonia

Lung adenocarcinoma may occasionally present with radiographic features resembling organizing pneumonia (OP), resulting in diagnostic uncertainty, delayed recognition, and the risk of inappropriate management. We present a case of a 77-year-old man with diabetes mellitus, hypertension, and ischemic heart disease who developed bilateral pulmonary infiltrates. Radiological findings initially suggested OP; however, histopathological examination revealed a moderately differentiated mucinous adenocarcinoma favoring a primary lung tumor. This case underscores a significant diagnostic pitfall and highlights the necessity of histological confirmation when encountering atypical radiologic features.