Metastatic Leydig cell tumour in a patient with synchronous prostate cancer.

Leydig cell tumours (LCTs) are rare testicular stromal tumours, comprising 1-3% of all testicular neoplasms. While typically benign, malignant transformation occurs in approximately 10% of cases, with metastasis being exceedingly rare. We present a case of a male in his 70s with a history of pT1 Leydig cell tumour who developed metastatic disease to the lungs and para-aortic lymph nodes, discovered during prostate cancer staging. This case highlights the challenges in diagnosing and managing metastatic LCT and underscores the importance of surveillance in patients with rare testicular malignancies.