Orbital Metastasis from Prostate Cancer: An Atypical Case of Neuroendocrine Dedifferentiation During Progression from Hormone-Sensitive to Refractory Stage

We report a case of orbital metastasis from a neuroendocrine dedifferentiated prostate cancer during progression from hormone-sensitive to hormone refractory stage. A patient receiving androgen deprivation for hormone-sensitive prostate cancer presented with sudden-onset rightsided ptosis and an increasing serum prostate-specific antigen level. Imaging studies revealed a mixed blastic and lytic lesion involving the right orbital wall and the right cavernous sinus. Comparison of the metastatic histology with the original pathology confirmed a histologic change to poorly differentiated prostate adenocarcinoma with neuroendocrine features. Local radiation of the lesion and palliative systemic chemotherapy resulted in marked short-term improvement of all presenting symptoms. Because prostate cancer metastasis involves hematogenous and lymphatic routes, we also evaluated expression of the vascular endothelial growth factor (VEGF) and receptors (VEGFR-1, VEGFR-2, and VEGFR-3) in the metastatic deposit by immunohistochemistry. Strong expression of VEGFR-2 and VEGFR-3 restricted to the malignant epithelium was noted. We recommend a second biopsy of atypical prostate metastasis associated with sudden change to aggressive clinical behavior in order to evaluate for dedifferentiation features before planning appropriate treatment interventions especially in patients who are candidates for systemic chemotherapy.