Hepatoid adenocarcinoma of the lung: Presenting mediastinal metastasis without transfer to the liver

Hepatoid adenocarcinoma of the lung (HAL) is a rare type of lung cancer. Its diagnosis and treatment may be difficult due to the varied presentation; however, immunohistochemical analysis facilitates the diagnosis. The present study presents a case of HAL. The patient was a 48-year-old male who presented with a primary complaint of back pain. A chest computed-tomography scan revealed a lobulated soft-tissue mass that extended from the left lung apex to the middle and posterior mediastinum. The area of the largest cross-section was 7.9×10.0 cm and the lymph nodes did not demonstrate metastasis. Immunohistochemical staining of a transbronchial lung biopsy revealed that the tumor cells were α-fetoprotein (AFP)(positive) and hepatocytes(positive) and a diagnosis of hepatoid carcinoma of the left lung was established. The level of serum AFP, a tumor marker, was elevated (6,283 ng/ml). The patient presented with mediastinal metastases and was classified as stage IIIA (N2); following diagnosis, the patient received concurrent chemoradiation. Subsequent to chemoradiation, the left lung lump with the largest cross-section was 3.3×4.2 cm and the serum AFP had fallen to its lowest level (23.11 ng/ml). However, when the patient relapsed, the serum AFP level elevated markedly (57,800 ng/ml). Furthermore, the nodules of metastasis increased in number and enlarged, with the largest measuring 2.1 cm. The patient succumbed as a result of a lung infection.