Non-Functioning Pituitary Adenomas

Excerpt

Pituitary adenomas comprise approximately 10-20% of intracranial tumors. Non-functioning pituitary adenomas (NFPAs) are benign adenohypophyseal tumors not associated with clinical evidence of hormonal hypersecretion. NFPAs comprise different histological subtypes, classified according to their immunostaining to different adenohypophyseal hormones and transcription factors. The silent gonadotroph adenoma is the most common subtype, followed by corticotroph, PIT1 (POU1F1) gene lineage, and null cell tumors. Patients with NFPAs usually come to medical attention as a result of “mass effects” symptoms such as headaches, visual disorders, and/or cranial nerve dysfunction caused by lesions large enough to damage surrounding structures. Hypopituitarism, caused by the compression of the normal anterior pituitary, and hyperprolactinemia due to pituitary stalk deviation can also be present. Some cases may be diagnosed incidentally through imaging studies performed for other purposes. Patients with NFPAs should undergo hormonal, clinical, and laboratory evaluation to rule out hyper and hypopituitarism. Assessment of prolactin and IGF-1 levels have been recommended in all patients whereas screening for cortisol excess is suggested in the presence of clinical symptoms. Impairment of pituitary function should be assessed by baseline hormonal measurements and/or stimulatory tests, if needed. Patients in whom the tumor abuts the optic chiasm should be submitted to visual field perimetry. Surgical resection is the primary treatment for symptomatic patients with NFPAs, i.e., those with neuro-ophthalmologic complaints and/or tumors affecting the optic pathway. Visual deficits and, less commonly, hormone deficiencies may improve following surgical treatment although new hormone deficiencies may also occasionally develop after a surgical approach. For patients with residual NFPAs following transsphenoidal surgery, a therapeutic attempt using cabergoline can be made according to clinical judgment in individual cases. Radiotherapy in the postoperative period is not consensual and is generally reserved for cases of tumors not completely resected by surgery, those cases that present progressive tumor growth during follow-up, or for patients who, at diagnosis, already have tumors with aggressive features. Highly aggressive tumors need special care during follow-up, including temozolomide with or without radiotherapy complementation or new potential emerging treatments. For patients with asymptomatic NFPAs a “watch and wait” option is reasonable. Follow up is individualized and should consider tumor size, prior treatments, and clinical symptoms. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.