Causas do Síndrome de Cushing

Cushing's Syndrome Causes

• Pituitary Adenoma (70%): Benign pituitary tumor (usually a microadenoma) overproduces ACTH. Rare, more common in women (8:1 ratio). Malignancy is rare; distinction from adenocarcinoma is based on patient progression.
• Ectopic ACTH/CRH-producing Tumors: Tumors outside the pituitary and hypothalamus. These tumors may synthesize CRH (stimulating ACTH release) or ACTH directly. Often linked to paraneoplastic endocrine syndromes. Common types include small cell lung cancer ("oat cell"), pancreatic carcinoma, bronchial adenoma, or carcinoid tumor. Clinical presentation is atypical, not the classic Cushing's syndrome picture. 50% of cases are small cell lung cancer.
• Iatrogenic Cushing's Syndrome (Most Frequent): Chronic, often excessive, glucocorticoid (cortisol, cortisone or synthetic derivatives) use, often to treat autoimmune conditions (rheumatoid arthritis, lupus) or other illnesses. Not a medical error, but a side effect.
• Adrenal Adenoma/Carcinoma: Tumors in adrenal glands producing cortisol autonomously, suppressing ACTH secretion. Usually benign microadenomas, treated surgically.
• Other Rare Causes:
  • Macronodular Adrenal Hyperplasia: Non-adenomatous cell proliferation.
  • Carney Complex: Adrenal hyperplasia, various tumors (cardiac, cutaneous, breast), speckled skin pigmentation (freckles, moles), precocious puberty, and schwannomas.
  • McCune-Albright Syndrome: Mutations in G-alpha protein. Features bone dysplasia, endocrine and cutaneous tumors, and café-au-lait spots.

Cushing's Syndrome Complications

• Hyperglycemia (10-15% Diabetes Mellitus): Elevated blood sugar due to glucocorticoids' anti-insulin effect (increased insulin resistance). Steroid diabetes can occur in poorly controlled diabetic patients with increased glucocorticoids. Not all patients with Cushing's will develop diabetes, but they will have greater carbohydrate intolerance.
• Pituitary Adenoma Complications: Clinical manifestations arise from mass effect (depending on tumor size). Headaches (often mild and respond to NSAIDs) are common. Symptom severity varies depending on the adenoma's compression. Symptoms are usually due to microadenomas, making them less pronounced.