Transdiaphragmatic herniation of liver tissue can rarely mimic intrapulmonary masses and is almost exclusively diagnosed as incidental finding during surgery. In a 77-year-old female smoker referred for work-up bullous pemphigoid, a potentially paraneoplastic condition, chest radiography demonstrated a right-sided supradiaphragmatic lung nodule. Transdiaphragmatic liver herniation was diagnosed prospectively by computed tomography (CT) and percutaneous lung biopsy and subsequently confirmed by surgery. Solid intrathoracic masses demonstrating isodense enhancement to liver tissue in CT suggest presence of ectopic liver tissue or herniated liver. We suggest that CT combined with percutaneous biopsy can be sufficient to establish diagnosis and to exclude a malignant condition.