Treatment of Stage IIB Seminoma in a Patient With Down Syndrome and Eisenmenger Syndrome: A Case Report

Abstract Background Management of testicular germ cell tumors in patients with complex comorbidities remains challenging. We present a case of stage IIB seminoma in a patient with Down syndrome (DS) and Eisenmenger syndrome (ES). Case Presentation A 37-year-old man with DS and ES underwent radical orchiectomy for a testicular mass, confirming seminoma (pT2N2M0R0S0). Following disease progression during surveillance, external beam radiation therapy (36 Gy in 18 fractions) was administered using a dog-leg field technique, as both chemotherapy and surgery were contraindicated. Treatment was well-tolerated with only mild nausea. Follow-up imaging showed near-complete response at 4 months, with stable disease at 12-month follow-up. Conclusion This case demonstrates radiation therapy as an effective, well-tolerated treatment for stage IIB seminoma. Despite theoretical concerns regarding radiosensitivity in DS and the hemodynamic risks of thoracic irradiation in ES, standard para-aortic/iliac radiation was delivered safely, achieving disease control without unexpected toxicity.