Pituitary adenoma

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

Small pituitary tumors (<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 microadenomas (<1 cm diameter) or macroadenomas (≥1 cm diameter); they may have suprasellar extension toward the optic chiasm, lateral extension into the cavernous sinuses, or downward extension into the sphenoid.

Patients with nonfunctional pituitary microadenomas require limited follow-up, but pituitary macroadenomas need to be followed for life.

Nonfunctional pituitary macroadenomas 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.

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

Pituitary adenomas are the third most common intracranial neoplasms in adults, accounting for about 10% of all intracranial tumors.[1]Surawicz TS, McCarthy BJ, Kupelian V, et al. Descriptive epidemiology of primary brain and CNS tumors: results from the Central Brain Tumor Registry of the United States, 1990-1994. Neuro Oncol. 1999 Jan;1(1):14-25. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1919458/pdf/11554386.pdf http://www.ncbi.nlm.nih.gov/pubmed/11554386?tool=bestpractice.com [2]Freda PU, Post KD. Differential diagnosis of sellar masses. Endocrinol Metab Clin North Am. 1999 Mar;28(1):81-117. http://www.ncbi.nlm.nih.gov/pubmed/10207686?tool=bestpractice.com They are diagnosed when patients present with hormone hypersecretion, plus visual and neurologic 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 nonfunctional adenomas (CNFPAs). CNFPAs and prolactinomas are the 2 most prevalent pituitary adenomas. CNFPAs are considered here. Functional pituitary adenomas (e.g., acromegaly, Cushing syndrome, prolactinoma) are not covered here.