Giant Prolactinoma Presenting with Neck Pain and Structural Compromise of the Occipital Condyles

Prolactinomas are the most common form of endocrinologically active pituitary adenoma; they account for ∼ 45% of pituitary adenomas encountered in clinical practice. Giant adenomas are those > 4 cm in diameter. Less than 0.5% of pituitary adenomas encountered in neurosurgical practice are giant prolactinomas. Patients with giant prolactinomas typically present with highly elevated prolactin levels, endocrinologic disturbances, and neurologic symptoms from mass-induced pressure. Described here is an unusual case of a giant prolactinoma presenting with neck pain and structural compromise of the occipital condyles. Transnasal biopsy of the nasopharyngeal portion of the mass obtained tissue consistent with an atypical prolactinoma with p53 reactivity and a high Ki-67 index of 5%. Despite the size and invasiveness of the tumor, the patient had resolution of his clinical symptoms, dramatic reduction of his hyperprolactinemia, and near-complete disappearance of his tumor following medical treatment.