Hepatoid Carcinoma of the Lung: A Rare Presentation

Hepatoid adenocarcinoma of the lung (HAL) is a rare pulmonary malignancy that resembles hepatocellular carcinoma morphologically and poses diagnostic challenges, particularly when alpha-fetoprotein (AFP) is absent. We report a man in his 50s with chronic obstructive pulmonary disease and a solitary 1.9-cm right upper lobe nodule. Percutaneous biopsy identified non-small cell carcinoma without establishing the subtype. Video-assisted thoracoscopic right upper lobectomy with mediastinal lymphadenectomy revealed a hepatoid tumour expressing HepPar-1 and CK7 but not AFP, arginase-1 or glypican-3. The absence of a hepatic lesion on staging imaging supported a pulmonary primary. The tumour was pT1bN0 with no clinically detected metastases. At 6 months after resection, there was no evidence of recurrence. This case illustrates the limitations of small biopsies and isolated immunohistochemical markers in diagnosing an AFP-negative pulmonary hepatoid tumour.