In this patient, given his age and the large lung mass with multiple pulmonary nodules, the possibility of a germ cell tumor was strongly considered. The β-hCG level was 36,806 mIU/mL (reference, 0-5 mIU/mL), α-fetoprotein level was normal, and serum lactate dehydrogenase level was 251 U/L (reference, 122-225 U/L). Considering the presence of multiple bullae, the α1-antitrypsin level was measured and was 273 mg/dL (reference, 83-199 mg/dL). Ultrasonography of the scrotum was done to rule out a primary testicular tumor, and revealed no masses or lesions. Histologic examination of a biopsy specimen with hematoxylin-eosin stain showed poorly differentiated cells (cytotrophoblasts) in sheets, with severe pleomorphism and extensive necrosis and hemorrhage, along with multinucleated giant cells resembling syncytiotrophoblasts (Fig 2A). The neoplastic cells were positive for keratin AE1/AE3 and β-hCG, and focally for p63 (Figs 2B, 2C). They were negative for α-fetoprotein, placental alkaline phosphatase, and cytokeratin 5/6. The characteristic appearance, along with strong positivity for β-hCG and absence of other tumors/lesions on radiologic imaging, supported the diagnosis of primary pulmonary choriocarcinoma. The patient was then started on chemotherapy with bleomycin, etoposide, and cisplatin regimen. On follow-up, after completion of four cycles of chemotherapy, the β-hCG levels came down to 3 mIU/mL (reference, 0-5 mIU/mL) with interval decrease in the size of the pulmonary hilar mass/nodules.