Direct Spread of Primary Testicular Lymphoma along the Gonadal Vessels Detected on F-18 Fluorodeoxyglucose Positron-Emission Tomography/Computed Tomography Imaging.

A 63-year-old male presented with left scrotal swelling and the ultrasound showed a large heterogeneous mass consistent with a testicular malignancy. The patient underwent left-sided orchiectomy which showed diffuse large B-cell lymphoma. The patient was then referred for whole-body F-18 fluorodeoxyglucose positron-emission tomography/computed tomography (FDG PET/CT) imaging which showed multiple hypermetabolic foci extending along the left inguinal canal to the retroperitoneum and the left perinephric space, suggesting direct contiguous spread of the tumor along the gonadal vessels, a form of metastasis unique to primary testicular lymphoma, and demonstrated for the first time on FDG PET/CT imaging.