Beyond the usual - Atypical imaging presentation in lung cancer and implications for TNM-staging

This review illustrates the spectrum of atypical computed tomography (CT) appearances of lung cancer and provides practical guidance for accurate diagnosis and staging.

While most lung cancers show typical CT features, certain subtypes present atypically, mimicking benign conditions or other malignancies. These include pneumonic-type adenocarcinoma, multifocal adenocarcinoma with ground-glass/lepidic features, lung cancer with air lucency, and pulmonary carcinoid tumors. Pneumonic-type adenocarcinoma often resembles infectious pneumonia, requiring careful CT evaluation, and tissue sampling for confirmation. Multifocal ground-glass/lepidic adenocarcinomas, most commonly seen in female never-smokers, are indolent with low metastatic potential. Lung cancers with air lucency, appearing as cysts, cavitary, or bullous lesions, challenge volumetric assessment and may benefit from adapted TNM measurements excluding air-space components. Pulmonary carcinoid tumors show variable imaging features and require tailored staging and management based on their differentiation and spread.

Accurate recognition of atypical CT manifestations of lung cancer is critical to avoid misinterpretation and inappropriate management. Integrating imaging characteristics with histopathologic and, when applicable, molecular data ensures correct staging and guides personalized therapy.