In ACTH-dependent Cushing's syndrome, the adrenal glands may be overstressed by a benign tumour of the pituitary gland. It is located in the pituitary fossa and is covered by the sellar diaphragm, located just below the hypothalamus. This gland is small and consists of two parts:
- the adenohypophysis consisting of an anterior part, with five types of cells defined by the hormones they produce and secrete and an intermediate part, which produces the melanocyte hormone.
- the neurohypophysis (posterior part) consists of nerve endings of cells that reside in the hypothalamus
Location and anatomy of the pituitary gland .
ACTH-independent is caused by problems in the adrenal glands. These are two triangular shaped glands located above each kidney in the retroperitoneal space. They are surrounded by perilesional fascia, extensive connectivity and adipose ossicles. They are divided into two structures: the medulla (central) and the adrenal cortex, a peripheral.
Its macroscopic structure is as follows (from inside to outside), the adrenal medulla, the reticular zone, the fascicular zone, the glomerular zone and the capsule. The fasciculated zone, the thickest part of the adrenal cortex, is made up of cells organised in a parallel fashion, separated by capillaries. It synthesises the glucocorticoid cortisol. The hypothalamic-pituitary corticotropic axis controls the secretion of glucocorticoid hormones via hypothalamic corticoliberin and pituitary ACTH.
It should also be noted that this syndrome has deleterious effects on other organs.
In the heart there are structural changes. The first is an increase in the mass of the left ventricle. It may show abnormal increase in volume or remodelling leading to cardiac dysfunction of the left ventricle. This means that there is an increase in the thickness of the myocardium (the muscle of the heart) in relation to the size of the chamber.
There are also structural changes in the small vessels (arterioles). Subclinical atherosclerosis is very common in these patients and they have increased intima media thickness.
Similarly, the distribution of adipose tissue, which is a connective tissue, leads to increased abdominal adiposity. It is composed of adypocytes, triglycerides, nervous tissue, vascular tissue and immune cells.
In the brain, the limbic system is particularly affected. It is composed of nuclei located under the cerebral cortex. Its main component is the hippocampus, where there is a reduction in its volume.
Immune dysfunction is also common with an increase in the number of circulating neutrophils. There is also a decrease in circulating lymphocytes and monocytes, which contribute to impaired immune defences.
References:
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