A neuroglial neoplasm in retroperitoneal lymph nodes: metastasis from a testicular teratoma with embryonic-type neuroectodermal tumour

Testicular germ cell tumours are a common solid malignancy amongst young men. Most non-seminomatous germ cell tumours in adults display mixed histological types, although can be purely one type. Rarely, some non-seminomatous germ cell tumours undergo somatic malignant transformation, whereby they can differentiate into diverse malignant phenotypes, which might resemble tumours found elsewhere in the body. Although uncommon, these transformations carry significant implications for prognosis and treatment. We present a case of a testicular teratoma with somatic malignant transformation to embryonic type neuroectodermal tumour. Unusually, the associated metastases to retroperitoneal lymph nodes show neuroglial differentiation without aggressive features. This case highlights the diagnostic challenges of teratomas with somatic malignant transformation, emphasizing the role of histopathology, immunohistochemistry, and molecular techniques in diagnosis and clinical decision-making.