Growth Hormone–Secreting Pituitary Carcinoma Presenting With Isolated Leptomeningeal Involvement: A Challenging Diagnosis

Objective: To raise awareness of the clinical presentation of growth hormone (GH)-producing pituitary carcinoma and its unique clinical presentation. Methods: A case report of a GH-secreting pituitary carcinoma with predominant leptomeningeal spread presenting as persistent acromegaly post–macroadenoma excision and radiation therapy. Results: A 39-year-old male, diagnosed with a GH-secreting pituitary macroadenoma with acromegaly 3 years prior, presented with persisting acromegalic phenotypic features with associated diabetes mellitus and hypertension. He had undergone an endoscopic transnasal, transsphenoidal adenoma resection, followed 3 months later by conventional cranial irradiation at another center 2 years prior to his current presentation to us. Serum insulin-like growth factor 1 and post 1-hour 100-g oral glucose administration serum GH levels were 1,198 and 393 ng/mL, respectively. Magnetic resonance imaging of the brain with spine screening revealed an empty sella, diffuse enhancing co...