Prolactin-Secreting Pituitary Carcinoma with Dural Metastasis: Diagnosis, Treatment, and Future Directions

Pituitary carcinoma is extremely rare, representing approximately 0.2% of all surgically resected pituitary neoplasms. It is thought to arise from World Health Organization grade II (atypical) pituitary adenomas. Pituitary carcinoma is defined by metastasis; it is otherwise indistinguishable from atypical pituitary adenomas, which can be considered carcinoma in situ. Pituitary carcinoma is difficult to diagnose and treat and is associated with poor long-term outcomes.

A 75-year-old man presented with a highly aggressive and treatment-refractory atypical prolactinoma that transformed into a prolactin carcinoma. Although the patient experienced early hormonal and surgical remission and local tumor control after tumor resection and fractionated radiation, isolated dural-based metastases were subsequently noted following gradual elevation in serum prolactin despite ongoing dopamine agonist therapy. En bloc resection was performed of the pathology-confirmed, prolactin-staining dural metastases. At 1-year follow-up, there was no further evidence of metastatic disease, and normalization of serum prolactin was observed.

Long-term surveillance using serum prolactin as a tumor biomarker and correlation to imaging studies were critical for the diagnosis and interval screening for recurrence. This technique can be applied to all secretory atypical pituitary adenomas to improve early detection of potential metastasis. Further research, especially of genetic and epigenetic characteristics, could readily improve the diagnosis and treatment of pituitary carcinomas.