Adrenal Gland Pathology Overview

Adrenal Gland Pathology

• The adrenal gland consists of two distinct regions: the cortex and the medulla.
• The medulla is part of the sympathetic nervous system and secretes catecholamines, crucial for stress responses (e.g., infection, shock, injury).
• The cortex is divided into three zones: zona glomerulosa, zona fasciculata, and zona reticularis.
• The zona glomerulosa produces mineralocorticoids (e.g., aldosterone). Aldosterone regulates sodium and chloride reabsorption in the kidneys, which reduces their loss in urine in exchange for potassium.
• Aldosterone's release isn't controlled by the pituitary gland but instead by the renin-angiotensin system.
• The zona fasciculata produces glucocorticoids.
• The zona reticularis produces androgen precursors like Dehydroepiandrosterone (DHEA) and some androstenedione.
• The amount of sex steroids produced in the zona reticularis is low in typical adults.
• Glucocorticoids impact various tissues and organs, regulating metabolic activities, including inhibiting protein synthesis, increasing protein breakdown, and increasing gluconeogenesis.
• Adrenal cortex abnormalities include hyperfunction (excess hormone production) and hypofunction (reduced hormone production), alongside tumors.
• Hyperaldosteronism, a type of hyperfunction, is due to excessive aldosterone production. This leads to sodium and water retention, hypertension, and potassium loss, potentially causing muscular weakness, cardiac arrhythmias, and metabolic alkalosis.
• Primary hyperaldosteronism (Conn's syndrome) is often caused by an adrenal adenoma of the zona glomerulosa but can sometimes be autoimmune hyperplasia. Renin levels are low.
• Secondary hyperaldosteronism is due to increased renin.
• Cushing's syndrome involves excessive glucocorticoid production. Symptoms include centripetal fat deposition (moon face, buffalo hump, trunk obesity), increased protein breakdown resulting in muscle wasting, particularly in the limbs, abdominal striae, osteoporosis which can lead to vertebral collapse, and delayed wound healing.
• Glucose tolerance can become unstable, causing frank diabetes in about 20% of cases. Hypertension and mental symptoms (depression, psychosis) can also occur.
• Elevated plasma cortisol levels or increased urinary 17-hydroxysteroid excretion (24 hour urinary cortisol) indicate Cushing's syndrome and are diagnostically useful.
• Cushing's syndrome can also be Iatrogenic, which is relatively common and results from high-dose glucocorticoid administration.
• Natural causes of Cushing's include tumors like pituitary adenomas (Cushing's disease), adrenal cortical neoplasms, and ectopic ACTH production in cancers.
• Bilateral adrenal cortex hyperplasia is a condition that can occur.
• Excess ACTH usually results in a low ACTH level.
• Excess androgen production in Cushing's syndrome, often seen in cases of adrenal carcinoma in women, causes hirsutism, amenorrhea, and virilization. The prognosis for adrenal carcinoma is poor.
• Differentiating adrenal adenoma from carcinoma is difficult, especially if no metastasis is present.

Adrenocortical Hypofunction

• Adrenocortical hypofunction involves the whole cortex, leading to a lack of both mineralocorticoids and glucocorticoids (e.g., reduced cortisol and aldosterone).
• This condition can be primary (due to adrenal gland issues) or secondary (from ACTH deficiency).
• Primary form can be acute (acute hemorrhagic necrosis) or chronic. Acute form is often caused by meningococcal septicemia or other acute septicemias, while severe algid malaria and DIC are other causes.
• The chronic form (Addison's disease) can affect any age but is mainly common in adults aged 30 to 50 and has links to destructive autoimmune adrenalitis, tuberculosis, amyloidosis, and haemochromatosis.
• It can be caused by metastatic tumors.

Adrenal Medulla Pathology

• The adrenal medulla pathologies primarily involve tumors: pheochromocytoma and neuroblastoma.
• Pheochromocytoma is a benign tumor originating from medullary chromaffin cells; it presents through catecholamine secretions leading to symptoms like hypertension, which can be intermittent, pallor, headaches, sweating, and nervousness. Diagnosis relies on measuring urinary vanillylmandelic acid (VMA), alongside CT scans and radioisotope scans.
• Neuroblastoma is a highly malignant childhood tumor arising from sympathetic nerve cells. It presents as a large abdominal mass in infants. Microscopically, neuroblastoma cells are small, round, and blue, typically forming rosette patterns.