Primary Extragonadal Choriocarcinoma Presenting with Pneumothorax in an Elderly Male Patient: A Case Report

Introduction: Choriocarcinoma is a highly malignant trophoblastic tumor and occurs exclusively as nongestational choriocarcinoma in male patients, which is extremely rare. Choriocarcinoma frequently presents with multiorgan metastasis and is associated with poor prognosis. Spontaneous pneumothorax associated with pulmonary malignancy is an uncommon presentation of choriocarcinoma, and pneumothorax in untreated patients with nongestational choriocarcinoma may be an initial manifestation and an indicator of aggressive tumor behavior. Case Presentation: An 80-year-old man presented with cough and dyspnea. Chest computed tomography revealed right pneumothorax and numerous bilateral pulmonary nodules in addition to mediastinal lymphadenopathy and hepatic lesions. Persistent air leakage required thoracoscopic surgery. Partial lung resection led to the identification of hemorrhagic and necrotic nodules, which were positive for GATA binding protein 3, human chorionic gonadotropin, and CK7 by immunohistochemistry, and the definitive diagnosis was choriocarcinoma. Serum human chorionic gonadotropin level was markedly elevated (17,000 mU/mL). Positron emission tomography/computed tomography revealed no abnormalities in testes, suggesting primary extragonadal choriocarcinoma. Despite initial postoperative improvement, the disease progressed rapidly and the patient died on hospitalization day 24. Discussion: Albeit rare in elderly male patients, nongestational choriocarcinoma can present with widespread metastasis and rapid progression. Spontaneous pneumothorax is an unusual complication of malignant pulmonary tumors and may result from subpleural tumor necrosis in highly vascular tumors, such as choriocarcinoma. This case illustrates that pneumothorax in untreated pulmonary malignancy may reflect high tumor aggressiveness, underscoring the need for early pathologic evaluation and timely decision-making. Conclusion: This rare presentation of primary extragonadal choriocarcinoma in an elderly male manifesting as pneumothorax highlights that choriocarcinoma should be considered in the differential diagnosis of unexplained pneumothorax or multiple pulmonary nodules, regardless of age. Early diagnostic intervention is essential for optimal patient outcomes.