Background: Prolactinomas invading the skull base are rare, and could easily be confused with skull base tumors of nonpituitary origin.
Case description: We report a series of 4 cases of giant prolactinomas invading the skull base and presenting with atypical symptoms. Case 1 presented with a short history of headache and nasal obstruction. Case 2 presented with progressive hypoacusia, dizziness, and ophthalmoplegia. In Case 3, the patient developed rapid progressive visual failure and psychiatric symptoms. Case 4 presented with a 1-year history of headache and retrorbital pain. The diagnosis of prolactinoma was made on the basis of tumor immunohistochemistry and/or high plasma prolactin levels (range from 650-6,500 ng/mL). Medical treatment with the dopamine agonist cabergoline was given; it was effective in normalizing prolactin levels and inducing tumor shrinkage.
Conclusion: Prolactin levels should be measured in all large skull base tumors involving the pituitary region before any surgery or inappropriate radiotherapy is performed.