Pituitary adenoma

Clinically non-functional pituitary adenomas (CNFPAs) are considered here; functional pituitary adenomas (e.g., acromegaly, Cushing's syndrome, prolactinoma) are dealt with separately.

Small pituitary tumours (<4 mm) are common and have been reported in up to 10% of MRIs in the general population. Only a small fraction of such tumours are associated with clinical features suggestive of pituitary disorder.

Radiologically, CNFPAs are classified as micro-adenomas (<1 cm diameter) or macro-adenomas (≥1 cm diameter); they may have suprasellar extension towards the optic chiasm, lateral extension into the cavernous sinuses, or downward extension into the sphenoid.

Patients with non-functional pituitary micro-adenomas require limited follow-up, but pituitary macro-adenomas need to be followed for life.

Non-functional pituitary macro-adenomas typically come to medical attention with features of mass effect such as headaches, visual field deficits, hypopituitarism, and rarely cranial nerve palsies.

A modest elevation of prolactin may occur in CNFPAs due to compression of the pituitary stalk and interruption of intrinsic dopaminergic tone.

Trans-sphenoidal surgery is the first-line therapy for patients with CNFPAs and mass effect.

Pituitary adenomas account for about 15% of all intra-cranial tumours.[1]Melmed S. Pituitary-Tumor Endocrinopathies. N Engl J Med. 2020 Mar 5;382(10):937-50. http://www.ncbi.nlm.nih.gov/pubmed/32130815?tool=bestpractice.com ​​​ They are diagnosed when patients present with hormone hypersecretion, plus visual and neurological deficits and hypopituitarism as a result of mass effect. They may also be found as pituitary incidentalomas. Pituitary adenomas that do not cause a characteristic hormone hypersecretion syndrome (null cell and the majority of gonadotroph adenomas) are referred to as clinically non-functional adenomas (CNFPAs). CNFPAs and prolactinomas are the 2 most prevalent pituitary adenomas. CNFPAs are considered here. Functional pituitary adenomas (e.g., acromegaly, Cushing's syndrome, prolactinoma) are not covered here. See Acromegaly; Cushing Syndrome; Prolactinoma.