Spontaneous regression of anterior mediastinal seminoma with normalization of β-human chorionic gonadotropin levels

INTRODUCTION: Although spontaneous regression (SR) of anterior mediastinal seminoma is very rare with normalization of β-human chorionic gonadotropin (β-hCG) level, video-assisted thoracic surgery (VATS) is the most effective solution for definite diagnosis of indeterminate anterior mediastinal masses. DIAGNOSIS, THERAPEUTIC INTERVENTIONS, AND OUTCOMES: A rare case of an asymptomatic 37-year-old man with an anterior mediastinal mass that was detected on a routine chest X-ray is presented. Computed tomography (CT) showed a large anterior mediastinal tumor with superior vena cava invasion and SR before VATS for definitive diagnosis. On pathology, the definitive diagnosis was seminoma. Microscopic examination showed abundant apoptotic cells within the tumor. Chemotherapy (bleomycin 30 mg/day, etoposide 200 mg/day, cisplatin 40 mg/day) was given to this patient, and the tumor showed high sensitivity. CONCLUSION: Anterior mediastinal seminoma showing SR induced by spontaneous apoptosis of tumor cells may have good sensitivity to chemotherapy, and a good clinical outcome may be achieved in these patients. This case also highlights that VATS is the most effective solution for definite diagnosis of indeterminate anterior mediastinal masses.