A Rare Metastatic Route in Prostate Cancer: A Case Report

Abstract

Introduction Testicular metastasis from prostate cancer (PCa) is an extremely rare phenomenon mostly observed in patients with high-grade disease. It occurs in approximately 0.5% of patients with metastatic disease. Case Presentation We present a 63-year-old man with a history of locally advanced PCa (cT3bN1M0) characterized by pure adenocarcinoma, ISUP Grade Group 3, and an initial PSA of 11.8 ng/mL. The patient underwent external beam radiation therapy (50 Gy /25 fr), high-dose-rate brachytherapy (9 Gy/2 fr) and ADT with a PSA nadir of 0.07 ng/mL. Five months after completing ADT, the PSA level began to rise to 3.28 ng/ml. CT and prostate MRI revealed a heterogeneous contrast-enhancing mass within the left testis, resembling a primary testicular tumor. Testicular cancer tumor markers were normal. The patient underwent left radical orchofuniculectomy. Histopathological and immunohistochemical analysis confirmed a highgrade metastatic prostate adenocarcinoma with cribriform growth pattern (ISUP Grade Group 5). Following the surgery, PSA level dropped to 0.04 ng/mL and remained stable for nearly two years, with a recent slight rise to 0.38 ng/mL. CT, MRI and bone scintigraphy have shown no evidence of recurrence. ADT is planned if PSA rises. Discussion Testicular metastasis in PCa may present either as an isolated lesion or as a part of widespread metastatic involvement. The interval between definitive treatment and the development of testicular metastasis can vary widely, ranging from several months up to 22 years. Clinically, testicular involvement may be asymptomatic or manifest as a painful palpable mass, swelling, or even mimic orchitis. The introduction of PSMA/PET-CT has proven particularly valuable in such cases, demonstrating high sensitivity in detecting metastatic lesions even at rare sites. The primary management approach is radical orchiectomy, with most reported cases of isolated testicular metastasis subsequently managed with ADT. However, in our case, ADT was not initiated immediately; instead, the patient was placed under close biochemical surveillance, potentially avoiding or delaying the systemic therapy and its adverse effects. Conclusions This case highlights the rarity of testicular metastasis from PCa and suggests that vigilant monitoring of PSA level may be a suitable alternative to immediate systemic therapy in selected patients.