Abstract Introduction Embryonal carcinoma, a non-seminomatous germ cell tumor (NSGCT), is a highly aggressive malignancy in young men, often demonstrating early hematogenous spread to the lungs. Pulmonary involvement—manifesting as multiple nodules, tumor emboli, or vascular invasion—typically signifies advanced disease. We present a stage IIIC, poor-risk embryonal carcinoma with predominant thoracic manifestations initially mimicking primary lung pathology, underscoring the importance of considering metastatic germ cell tumors in young men with unexplained pulmonary nodules or embolic phenomena. Case Description A 28-year-old previously healthy man presented with right testicular pain and progressive low back pain radiating to the left leg. Initial ultrasound suggested epididymitis. Within days, he developed worsening dyspnea. Chest CT revealed innumerable bilateral pulmonary nodules, a left lower lobar pulmonary embolism with segmental extension, and bulky retroperitoneal lymphadenopathy invading the inferior vena cava (IVC), left renal vein, and right atrium—findings concerning for extensive thoracic metastases and tumor thromboembolism. Lower extremity Doppler was negative for deep vein thrombosis, suggesting tumor-related rather than thrombotic PE.Laboratory evaluation showed markedly elevated LDH (2480 IU/L), normal AFP (11 ng/mL), and β-HCG 2 mIU/mL. CT-guided biopsy of a pulmonary nodule confirmed metastatic germ cell tumor consistent with embryonal carcinoma. Lumbar spine biopsy revealed osseous metastases with epidural extension (T12-L2). Repeat scrotal ultrasound demonstrated no primary testicular mass, consistent with a “burned-out” primary lesion.Management included corticosteroids for spinal cord compression risk, palliative spinal radiation (30 Gy in 10 fractions), systemic chemotherapy (initial etoposide-cisplatin followed by bleomycin-etoposide-cisplatin), and anticoagulation transitioned from heparin to apixaban for tumor embolism. Discussion This case highlights an uncommon pulmonary presentation of embryonal carcinoma characterized by diffuse metastatic nodules, tumor thromboembolism, and cardiac extension—mimicking primary thoracic malignancy or thromboembolic disease. The absence of deep venous thrombosis and emboli resistant to anticoagulation should prompt consideration of tumor embolism. Radiographically, the “cannonball” appearance of pulmonary nodules is classic for germ cell metastases but may be mistaken for carcinoma of other origins or septic emboli. “Burned-out” testicular tumors pose diagnostic challenges, as the primary site may be undetectable despite disseminated disease. Early biopsy of atypical pulmonary lesions in young men and integration of imaging, tumor markers, and tissue diagnosis are critical for accurate classification and treatment. Classified as poor-risk by IGCCCG criteria (elevated LDH and non-pulmonary visceral metastases), prognosis remains guarded, with 54% progression-free and 67% overall survival. Prompt systemic chemotherapy is essential to mitigate respiratory compromise and embolic complications. This abstract is funded by: None
Khetani et al. (Fri,) studied this question.