Pituitary Mass / Tumor
A pituitary mass or tumor is an abnormal growth in or around the pituitary gland, the small but crucial endocrine gland located at the base of the brain. While the majority of pituitary masses are benign adenomas (non-cancerous tumors), other lesions can occur in this region including cysts, craniopharyngiomas, meningiomas, and rarely, metastatic cancers. These masses can cause symptoms through hormone overproduction, hormone deficiency from compression of normal pituitary tissue, or mass effect on surrounding structures such as the optic nerves, causing vision problems.
What is it?
The pituitary gland sits in a small bony cavity called the sella turcica at the base of the skull, directly behind the nasal passages. This “master gland” controls multiple hormone systems throughout the body by producing and releasing hormones that regulate growth, metabolism, reproduction, stress response, and other vital functions. A pituitary mass can arise from the pituitary gland itself or from adjacent structures. Pituitary adenomas—benign tumors of the gland—account for approximately 15% of all intracranial tumors and are classified by size (microadenomas less than 10 mm, macroadenomas 10 mm or larger) and by hormone production (functioning or non-functioning).
Other masses in the pituitary region include Rathke’s cleft cysts (benign developmental cysts), craniopharyngiomas (benign but locally aggressive tumors arising from embryonic tissue), meningiomas (tumors of the meninges that can compress the pituitary), hypophysitis (inflammation of the pituitary), pituitary apoplexy (sudden hemorrhage or infarction of a pituitary tumor), metastatic tumors (rarely, cancers from breast, lung, or other sites spread to the pituitary), and aneurysms of nearby blood vessels that can mimic pituitary masses. The location of the pituitary gland is critical—directly above sits the optic chiasm (where the optic nerves cross), and on either side are the cavernous sinuses containing critical blood vessels and cranial nerves. Large pituitary masses can compress these structures, causing vision loss, double vision, or other neurological symptoms.
Important to Know
Symptoms of pituitary masses depend on tumor type, size, and hormone activity. Hormonal symptoms occur when functioning adenomas produce excess hormones—prolactinomas cause menstrual irregularities, infertility, and inappropriate lactation; growth hormone-secreting tumors cause acromegaly (enlarged hands, feet, facial features); ACTH-secreting tumors cause Cushing’s disease (weight gain, easy bruising, high blood pressure, diabetes); and rarely, TSH-secreting tumors cause hyperthyroidism. Conversely, large masses can compress normal pituitary tissue causing hypopituitarism—deficiency of one or more pituitary hormones leading to fatigue, low blood pressure, intolerance to cold or stress, sexual dysfunction, and other symptoms. Mass effect symptoms include vision problems (the most concerning, resulting from compression of the optic chiasm causing peripheral vision loss or “bitemporal hemianopsia”), headaches (from stretching of the dura covering the sella), and cranial nerve palsies causing double vision if the tumor extends into the cavernous sinus. Diagnosis requires pituitary-protocol MRI with gadolinium contrast for optimal visualization, comprehensive hormonal evaluation including pituitary function tests, and formal visual field testing if there’s concern for optic chiasm compression. Treatment is tailored to tumor type: prolactinomas typically respond to medication (dopamine agonists); most other functioning adenomas and symptomatic macroadenomas require transsphenoidal surgery (minimally invasive approach through the nose); radiation therapy may be used for residual or recurrent tumors; and small, non-functioning tumors may be observed with serial imaging. The prognosis varies—benign pituitary adenomas have excellent outcomes with appropriate treatment, though some patients require lifelong hormone replacement therapy if normal pituitary function doesn’t recover after treatment.