Ectopic Parathyroid Hormone Expression in Nonmetastatic Prostate Cancer

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• Ectopic parathyroid hormone (PTH) secretion is an uncommon cause of hyperparathyroidism.
• Prostate cancer, particularly nonmetastatic forms, rarely exhibits ectopic PTH production.

Observation:

• A 60-year-old man presented with hyperparathyroidism and hypophosphatemia, with normal calcium levels.
• Two years later, he was diagnosed with prostate adenocarcinoma; bone scans excluded metastases.
• Elevated urinary calcium excretion was noted, and parathyroid imaging was negative for adenoma.

Findings:

• Following successful prostate cancer treatment, both hyperparathyroidism and hypophosphatemia resolved.
• Immunostaining of prostate cancer tissue confirmed ectopic PTH expression.
• This case identifies ectopic PTH secretion as a cause of hyperparathyroidism in prostate cancer.

Implications:

• Recognizing ectopic PTH expression is vital for accurate diagnosis and management of prostate cancer patients with hyperparathyroidism.
• This finding expands the differential diagnosis of hyperparathyroidism beyond common causes.
• Understanding rare paraneoplastic syndromes is crucial in oncology.