Imaging characteristics of benign and malignant testicular Leydig cell tumors: A case report and literature review

Testicular Leydig cell tumors (LCTs) are rare sex cord‑stromal neoplasms, accounting for approximately 1%–3% of all testicular tumors, with a reported malignancy rate of 2.5%. This case report presents two elderly male patients (aged 73 and 71 years) with pathologically confirmed testicular LCTs—one malignant and one benign—highlighting the distinctive imaging findings that differentiate benign from malignant LCTs. The malignant case presented as a large (4.5 cm), heterogeneous mass with abundant intratumoral blood flow on ultrasound, along with restricted diffusion and heterogeneous marked enhancement on magnetic resonance imaging (MRI). In contrast, the benign case appeared as a small (1.1 cm), well‑defined hypoechoic nodule with punctate blood flow signals on ultrasound, and showed no restricted diffusion with arterial‑phase enhancement and delayed washout on MRI. The diagnosis of Leydig cell tumor was confirmed histopathologically in both cases, with immunohistochemical support in Case 2. This report provides a side‑by‑side comparison of benign and malignant LCTs based on multimodal imaging, and highlights key imaging features that distinguish these two entities. These findings underscore the importance of combining ultrasound with contrast‑enhanced MRI for preoperative characterization of testicular LCTs. Radiological distinction is of value for surgical planning.