Metachronous solitary metastasis from left testicle seminoma presenting as a large intracranial tumor 4 years post-treatment: a case report and review of the literature

BACKGROUND: Seminoma is a highly curable testicular tumor, but metastatic spread to the central nervous system (CNS) is uncommon, and isolated CNS relapse is exceptionally rare. In this article, we describe a rare case of isolated CNS relapse presenting as a large brain tumor four years after completion of therapy for testicular stage IIB seminoma. CASE PRESENTATION: A 34‑year‑old Syrian male with a history of successfully treated left testicular seminoma four years earlier presented to the Neurology Department with headaches, vomiting, and right‑hand weakness. Brain magnetic resonance imaging (MRI) revealed an intra‑axial mass initially suspected to be a glioma based on imaging characteristics. However, after surgical resection, histopathological examination and immunohistochemical analysis confirmed the lesion to be a metachronous seminoma metastasis to the brain (refer to Graphical Abstract). CONCLUSION: This report highlights the importance of considering metachronous seminoma metastasis to the brain in the differential diagnosis when neurological symptoms suggest an intracranial lesion, even for an extended period after completion of treatment for the primary tumor, despite the rarity of such metastases. Current surveillance guidelines for stage II seminoma do not include routine brain imaging. This case underscores the need for a high index of clinical suspicion and a low threshold for brain imaging in symptomatic patients, even years after treatment. Future research should identify risk factors for CNS relapse.