Pituitary adenomas at a glance

There exist different types of adenoma, depending on which hypophysis cells are affected. The pituitary somatotropic adenoma responsible for gigantism and acromegaly is the third most frequent pituitary adenoma. The first, in terms of frequency, is prolactinoma or the lactotropic adenoma. It represents 50 to 60% of all pituitary adenoma and causes a hypersecretion of prolactin, which in mammals is involved in amongst other things the growth of mammary glands and in the stimulation and synthesis of milk. Women affected by this pathology can have amenorrhea-galactorrhea syndrome, in other words the absence of menstruation and the production of milk outside of periods of breast feeding. Whilst most common in women prolactinoma can equally affect men, where it thus manifests itself by symptoms such as erection problems and/or a drop of libido levels. The second most common type of pituitary adenoma is non-secreting adenoma. As its name suggests in the case of such an adenoma cell tumours increase but do not secrete an excess of hormones. Nevertheless the adenoma can squeeze neighbouring structures (leading to visual disorders, etc.).

Cushing’s syndrome, named after the neurosurgeon who described this disease in 1932, is the consequence of a corticotropic adenoma. The pituitary cells secreting too many adrenocorticotropic hormones (ACTH), the consequence is an excessive secretion of cortisol by the adrenal glands which the ACTHs stimulate. The symptoms of this disease are hypertension, diabetes, a typically ‘Cushingoid’ figure (a red and swollen face, lipidic formations on the neck and nape, a reduction of muscle volume in the legs and arms, etc.), frequent bruising, a fine and fragile skin, etc. Finally, a thyrotropic adenoma, which is very rare (1% of all cases), brings about a hypersecretion of the thyroid stimulating hormone which is expressed by hyperthyroidism.

A disease which affects one person in a 1000

‘All these pituitary adenoma, depending on their size, take up a lot of space and compress other pituitary cell lines or neighbouring structures such as the optic chiasma or occulo-motor nerves. They can thus be at the root of numerous problems,’ points out Professor Albert Beckers, Head of the Endocrinology Department at the Liège University Hospital Centre (CHU). If the prevalence of these pituitary tumours was up until recently estimated to be one case for 5000 individuals, a study directed by Albert Beckers and carried out on a well defined population of the province of Liège shows that the prevalence of these affections is rather one case for a 1000 people. The results of this study were published in 2006 in The Journal of Clinical Endocrinology & Metabolism (1).