Isolated Cervical Seminoma Without Testicular or Mediastinal Primary: A Rare Extragonadal Germ Cell Tumor Presentation.

Germ cell tumors (GCTs) most commonly arise in the testes, with 1%-5% occurring at extragonadal sites, typically along the midline such as the mediastinum or retroperitoneum. We present a case of an exceptionally rare extragonadal seminoma confined to the cervical lymph nodes. Given the atypical location, diagnosis was difficult and required multiple biopsies to ensure appropriate correlation with histologic, immunophenotypic, and cytogenetic findings. Detection of 12p gain by FISH was pivotal in confirming germ cell origin. This case emphasizes the importance of maintaining a broad differential for atypical lymphadenopathy and will review the diagnostic challenge provided by this presentation.