Single Orbital Metastasis in Castration-Resistant Prostate Cancer

Introduction: Orbital metastasis of prostate cancer (PC) is very rare and even more unique in castration-resistant PC (CRPC). In this scenario, choline positron emission tomography/computed tomography (choline PET/CT) is the gold-standard restaging method of choice available in our setting, and new anti-androgens treatments show improvement in overall survival. Case presentation: We report the case of a 69-year-old male patient diagnosed with PC, treated with radical prostatectomy, and salvage radiotherapy after biochemical recurrence. After new prostate-specific antigen (PSA) progression, androgen deprivation therapy (ADT) was started. Four and a half years later, and already labeled as non-metastatic CRPC with a negative extension study, including choline PET/CT, he developed an accidental left frontal head trauma, presenting with proptosis, palpebral oedema, and oculomotor disorder. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a destructive bone lesion in the left orbit, associated with a soft tissue mass. These findings, suggestive of a neoplastic lesion, were histologically confirmed PC metastasis. Treatment was initiated with abiraterone, with a rapid improvement of symptoms, a progressive decrease of PSA, and a significant radiological response. Conclusion: Orbital metastases may present with proptosis and should be considered in patients with a history of cancer. If the ocular-orbital disease is suspected, the nuclear medicine physician should be aware that the choline PET/CT imaging includes the orbits. Tolerability and response to treatment with abiraterone were excellent.