Screening for ACTH-dependent hypercortisolism in patients with pituitary incidentaloma

An Overview of Pituitary Incidentalomas: Diagnosis, Clinical Features, and Management

Simple Summary

A pituitary incidentaloma is a pituitary tumor or mass that is incidentally discovered in imaging studies which have been performed for reasons other than the symptoms of pituitary lesions. The majority of pituitary incidentalomas are pituitary neuroendocrine tumors (PitNETs) and Rathke cleft cysts. PitNETs have received attention because of their distinction from pituitary adenoma in the new World Health Organization (WHO) classification. The natural history of PitNETs is partially known, and the management of pituitary incidentalomas has been determined based on this history; however, the pathology of PitNETs has significantly changed with the new WHO classification, and studies with a high level of evidence are required to consider treatment guidelines for pituitary incidentalomas.

Abstract

Pituitary incidentalomas are tumors or mass lesions of the pituitary gland. These are incidentally discovered during imaging studies for symptoms that are not causally related to pituitary diseases. The most common symptom that triggers an examination is headache, and the most common type of pituitary incidentalomas are pituitary neuroendocrine tumors (PitNETs) and Rathke cleft cysts. The existing treatment strategy is controversial; however, surgical resection is recommended in cases of clinically non-functioning PitNETs with optic chiasm compression. In contrast, cystic lesions, such as Rathke cleft cysts, should be followed if the patients are asymptomatic. In this case, MRI and pituitary function tests are recommended every six months to one year; if there is no change, the follow-up period should be extended. The natural history of PitNET is partially known, and the management of pituitary incidentalomas is determined by this history. However, the pathogenesis of PitNET has significantly changed with the new World Health Organization classification, and follow-up is important based on this new classification. Therefore, a high level of evidence-based research is needed to consider treatment guidelines for pituitary incidentalomas in the future.

Pituitary incidentaloma

Pituitary incidentalomas (PI) are lesions of the pituitary region discovered fortuitously by imaging for reasons unrelated to pituitary disease. They range from small cysts to large invasive adenomas. All over the world, improvements in the quality and availability of radiological examinations are leading to an increase in the discovery of PI. In the last four decades, significant advances have been made in the understanding of PI. Autopsy studies have shown that about 10% of deceased individuals harbour a PI, most often a non-functioning microadenoma. In contrast, modern patient series showed that among PIs that come to endocrinological attention, a significant proportion are macroadenomas, and many patients suffer from asymptomatic or pauci-symptomatic endocrine or ophthalmologic disturbances. Other than adenomas, empty sella, Rathke's cleft cyst, craniopharyngioma and meningioma are the most frequent types of PIs. About 10% of micro-incidentalomas and 25% of macro-incidentalomas grow over time. Most cases can be managed conservatively by mere surveillance. Follow-up is necessary in all patients with macroadenoma, but uncertainty remains for microadenomas as to the extent of endocrinological work-up as well as the necessity and duration of follow-up. Visual and endocrine anomalies constitute the most common indications for surgery. When needed, surgery yields better outcome in PIs than in symptomatic pituitary lesions.