Pituitary Macroadenoma

During a workup for dementia, a 77-year-old man was found to have a pituitary macroadenoma (21 x 17 x 25 mm) with suprasellar extension on a coronal-section MRI scan. The patient had hypertension and mild erectile dysfunction. He denied headaches, nausea, vision problems, weight changes, weakness, and polyuria. His medications included nifedipine, hydrochlorothiazide, and aspirin.

The patient’s blood pressure was 150/80 mm Hg. He had no cushingoid or acromegalic features. A left inferolateral visual field defect was noted by confrontation method. He had lipomatosis without gynecomastia, Tanner stage 4 hair distribution on inguinal and axillary regions, and normal-sized testicles. He had no hormonal deficiencies or excess; prolactin level was 11 μg/L (normal, 2 to 15 μg/L).

M. Usman Chaudhry, MD, of Moncton, New Brunswick, writes that pituitary tumors not associated with hormonal hypersecretion are termed “nonfunctional pituitary tumors.” They usually present with symptoms of mass effect, such as bitemporal visual field defect; headache; and palsy of cranial nerves III, IV, and VI. Most of these lesions are derived from gonadotroph cells and may produce luteinizing hormone or follicle-stimulating hormone, or subunits of these hormones.

In a patient who has a sellar mass, the diagnosis of nonfunctional pituitary tumor is usually made after prolactinoma, acromegaly, and Cushing disease have been ruled out clinically and biochemically. For lesions larger than 1 cm, neurosurgical removal is often necessary, and the pituitary cell origin is confirmed on histology. Medical therapy is not useful in most patients. Significant residual tumor is typically treated with radiation therapy.

This patient’s tumor was excised; histopathologic analysis confirmed a nonfunctional adenoma. Six weeks after the operation, the patient’s morning cortisol level remained adequate, 454 nmol/L (should be greater than 270 nmol/L for patients with pituitary disease); free thyroxine was 15.5 pmol/L (normal, 10.3 to 24.4 pmol/L); and total testosterone was 14.3 nmol/L (normal, 7.4 to 25.7 nmol/L).

Alpha subunit was not high, and he had no diabetes insipidus. A repeated coronal-section MRI scan of the pituitary showed residual tumor. The patient was referred for stereotactic radiosurgery.