The pituitary gland is a pea-sized (about 1 cm) structure that sits within the sella turcica (“Turkish saddle”), a cup-shaped depression in the sphenoid bone at the skull base. It is located behind the bridge of the nose, underneath the brain and optic chiasm.
Despite its small size, the pituitary gland the master regulator of the human *endocrine system, producing hormones also known as chemical messengers, that are released directly into the bloodstream. These hormones control and regulate metabolism, growth, reproduction, water balance and blood pressure. Hormone levels can be measured through blood and/ or urine tests.
Types of pituitary tumours
Pituitary adenomas are the most common growths in the sella and parasellar region. They are slow-growing benign tumours arising from the anterior pituitary tissue. In medical imaging, they are classified by size, growths < 1 cm are termed micro-adenomas and those > 1 cm are macro-adenomas. On the other hand, the clinical classification separates adenomas that are functioning meaning those that are hormonally active and non-functioning meaning those that do not have measurable evidence of hormonal activity. Whether the tumours are hormonally active or not, the imaging appearance on MRI is the same.
The commonest functioning, non-cancerous pituitary growth/ tumour is prolactinoma (PRL). This is followed by somatotrophinoma (growth hormone). Corticotropinoma is uncommon and secretes adrenocorticotropic hormone (ACTH) derivatives, resulting in Cushing syndrome.
Apart from benign tumours, there are also malignant tumours of the pituitary but these are rare, accounting for only < 0.5% of all pituitary tumours. Most of these malignant tumours are functional, exhibiting effects of increased prolactin or ACTH.
Imaging
Treatment
References
1. Shih RY, Schroeder JW and Koeller KK. Primary Tumors of the Pituitary Gland: Radiologic-Pathologic Correlation. Radiographics. Oct 1 2021. https://doi.org/10.1148/rg.2021200203
2. Du Four S, Van Der Veken J, Duerinck J, Vermeulen E, Andreescu CE, Bruneau M, Neyns B, Velthoven V and Velkeniers B (2022) Pituitary carcinoma – case series and review of the literature. Front. Endocrinol. 13:968692. doi: 10.3389/fendo.2022.968692
