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.