Abstract
A 55-year-old male with type 2 diabetes mellitus presented with a left lung mass on chest X-ray. Serum blood test showed an elevated carcinoembryonic antigen of 27.5 ng/mL with normal alpha-fetoprotein and protein induced by vitamin K absence or antagonist-II (PIVKA-II) levels. Computed tomography (CT) revealed a 73-mm oval mass in the left lower lobe S6 segment of the lung, left hilar lymphadenopathy, multiple nodules in liver segments S4/5, and multiple rib lesions. Bronchoscopy revealed a polypoid lesion in the left B6 bronchus, and biopsy demonstrated tumor cells resembling hepatocellular carcinoma. Immunohistochemical staining was diffuse positive for hepatocyte paraffin 1 (Hep Par 1) and CD10 and negative for thyroid transcription factor-1 (TTF-1), p40, synaptophysin, and cytokeratin 5/6 (CK5/6). In addition, programmed death-ligand 1 (PD-L1) expression by 22C3 immunohistochemistry was 40% positive for tumor cells, and the gene mutation analysis showed positive for Kirsten rat sarcoma viral oncogene homolog (KRAS) non-G12C mutation. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) of the liver showed poor enhancement of the tumor interior, ring enhancement, and decreased Gd-EOB-DTPA uptake, suggesting necrotic liver metastasis. The patient was diagnosed with advanced non-small cell lung cancer of unknown histological subtype with clinical T4N1M1c stage ⅣB. After optimizing blood glucose control with insulin, treatment with durvalumab, tremelimumab, carboplatin, and nab-paclitaxel was initiated. Toxicities included anemia requiring blood transfusion, but no other severe adverse events, including immune-related adverse events, were observed. Both the primary lung and metastatic liver lesion showed a tendency to shrink. This regimen may be considered a promising treatment for non-small cell lung carcinoma resembling hepatoid carcinoma as it achieved survival beyond the previously reported median.