2019 Volume 28 Issue 12 Pages 798-803
Pituitary metastases of prostate cancer are rare. We report a case of prostate adenocarcinoma that metastasized to the anterior pituitary gland. A 54-year-old man presented with bitemporal hemianopsia, consciousness loss, and coxalgia. His serum sodium level was 116 mmol/l. Magnetic resonance imaging (MRI) revealed an intrasellar tumor that showed inhomogeneous enhancement, and was attached to the optic chiasm. Laboratory examination revealed free testosterone level to be 0.5 pg/ml (reference range, 6.1-25.0). His hyponatremia improved following cortisol replacement, and was diagnosed to be due to relative adrenal insufficiency. Additional diagnostic studies including pelvic MRI, bone scintigraphy, and prostate needle biopsy revealed the presence of prostate adenocarcinoma (Gleason score 4+3=7) with multiple metastases to the vertebrae and pelvis. While receiving combined androgen blockade (CAB) therapy using the gonadotropin-releasing hormone antagonist degarelix acetate plus the antiandrogen bicalutamide, he presented with progressive visual field deficits. Subsequently, he underwent transsphenoidal surgery. Pathological examination of the resected tumor revealed it to be a metastatic adenocarcinoma of the anterior pituitary gland, which originated from the primary prostate cancer. Postoperatively, his bitemporal hemianopsia showed marked improvement. After docetaxel therapy and stereotactic radiotherapy, MRI showed significant shrinkage of the pituitary metastasis.
In this case, hypogonadism caused by pituitary metastases might pose androgen resistance of the prostate cancer. Therefore, careful evaluation including hormone load test prior to the treatment is highly recommended.
