Etiology and pathogenesis of endogenous hypercortisolism
Endogenous hypercortisolism develops due to internal disruptions in the endocrine system. For an accurate diagnosis, it is critically important to differentiate between the two main forms of this condition, as they involve completely different levels of lesion.
- Cushing's disease has an exclusively central origin. The primary link is a pituitary adenoma. This tumor begins to autonomously hypersecrete adrenocorticotropic hormone (ACTH). The excess ACTH in the blood secondarily hyperstimulates the adrenal cortex, forcing them to continuously produce glucocorticoids.
- Cushing's syndrome is characterized by a peripheral origin. In this case, the pituitary gland functions normally (or its activity is suppressed), and the cause of the disease is a primary space-occupying lesion in the adrenal glands themselves. This tumor carries out autonomous hormone hypersecretion, independent of central regulation.
Specific patient phenotype
Chronic glucocorticoid excess leads to the development of a readily recognizable appearance in the patient. Patients complain of rapid and very pronounced weight gain with specific features.
The disease is characterized by a dysplastic (centripetal) distribution of adipose tissue:
- A typical "moon face" with pronounced cheek hypertrophy forms.
- Fat is deposited in the cervicothoracic region, forming a "buffalo hump".
- Massive truncal (abdominal) obesity develops.
- Against the backdrop of a heavy torso, the limbs appear thinned due to muscle and fat tissue atrophy.
An additional, highly striking visual sign is specific skin changes — wide, purple striae (stretch marks).
Differential diagnosis in children
In pediatric practice, symptoms of hypercortisolism must be carefully distinguished from common constitutional-exogenous obesity.
The key differential diagnostic criterion is the dynamics of physical development. In Cushing's syndrome, a child exhibits pronounced growth retardation. This cardinally distinguishes it from exogenous obesity, in which the patient's height and bone age typically outpace the age norm.
The second major sign indicating endocrine pathology of adrenal or pituitary origin in an obese child is persistent arterial hypertension.
Medication-induced (iatrogenic) hypercortisolism
In addition to endogenous causes, the syndrome can be triggered artificially. The iatrogenic form develops as a direct consequence of long-term therapy with high doses of exogenous glucocorticoids.
Such aggressive treatment is usually due to severe underlying conditions requiring immunosuppression:
- Systemic connective tissue diseases (rheumatoid arthritis, dermatomyositis, scleroderma).
- Severe forms of bronchial asthma refractory to other control.
The clinical picture of the medication-induced syndrome is phenotypically identical to endogenous hypercortisolism: patients demonstrate the same centripetal type of obesity, striae, growth retardation, and elevated blood pressure.
For quick memorization: Disease is in the Brain (pituitary adenoma, central origin), Syndrome is the Adrenals themselves (peripheral tumor).
Class and exam questions
How to distinguish hypercortisolism from simple overeating in a child?
Endocrine pathology presents with pronounced growth retardation and arterial hypertension, whereas in exogenous obesity, bone age and height usually exceed the norm.
Why does the iatrogenic form of the syndrome occur?
It develops due to prolonged intake of high doses of exogenous glucocorticoids in the treatment of systemic connective tissue diseases or severe asthma.
What else to study on this topic
- Feedback mechanism in the hypothalamic-pituitary-adrenal axis
- Pathogenesis of wide purple striae formation in glucocorticoid excess
- Mechanisms of arterial hypertension development in hypercortisolism
- Assessment of bone age in the differential diagnosis of obesity in children
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Other topics in the section «Chapter 11. Endocrine Diseases in Children»
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