Pituitary adenoma

Pituitary adenoma
Visual field loss in bitemporal hemianopsia: peripheral vision loss affecting both eyes, resulting from a tumor – typically a pituitary adenoma – putting pressure on the optic chiasm
Specialty	Oncology, endocrinology

Pituitary adenomas are tumors that occur in the pituitary gland. Most pituitary tumors are benign, approximately 35% are invasive and just 0.1% to 0.2% are carcinomas.^[1] Pituitary adenomas represent from 10% to 25% of all intracranial neoplasms and the estimated prevalence rate in the general population is approximately 17%.^[1][2]

Non-invasive and non-secreting pituitary adenomas are considered to be benign in the literal as well as the clinical sense, though a 2011 meta-analysis of available research showed that there were, then, scant studies – all of poor quality – to either support or refute this assumption.^[3]

Adenomas exceeding 10 mm (0.39 in) in size are defined as macroadenomas, with those smaller than 10 mm (0.39 in) referred to as microadenomas. Most pituitary adenomas are microadenomas and have an estimated prevalence of 16.7% (14.4% in autopsy studies and 22.5% in radiologic studies).^[2][4] A majority of pituitary microadenomas often remain undiagnosed, and those that are diagnosed are often found as an incidental finding and are referred to as incidentalomas.

Pituitary macroadenomas are the most common cause of hypopituitarism.^[5][6]

While pituitary adenomas are common, affecting approximately one in 6 of the general population, clinically active pituitary adenomas that require surgical treatment are more rare, affecting approximately one in 1,000 of the general population.^[7]