[Cushing's syndrome. Recent findings]

Area of Science:

• Endocrinology
• Oncology

Background:

• Cushing's syndrome is classified into ACTH-dependent (pituitary adenoma, ectopic tumors) and ACTH-independent (adrenal tumors, iatrogenic) forms.
• Specific subtypes include nodular adrenal hyperplasia and micronodular adrenal dysplasia, the latter associated with Carney's complex and ACTH receptor antibodies.
• Diagnosis involves confirming hypercortisolism and identifying the cause, which can be complicated by various conditions and medications affecting the hypothalamic-pituitary-adrenal axis.

Discussion:

• The diagnostic process for Cushing's syndrome necessitates differentiating between ACTH-dependent and independent etiologies.
• Challenges in diagnosis arise from conditions mimicking Cushing's, such as depression, alcoholism, and certain medications, as well as the intermittent nature of the syndrome.
• Distinguishing between pituitary and ectopic ACTH hypersecretion can be difficult due to overlapping clinical and laboratory findings.

Key Insights:

• Eighty percent of ACTH-dependent Cushing's syndrome stems from pituitary adenomas, while 15% result from ectopic ACTH/CRH secretion.
• Micronodular adrenal dysplasia, a rare ACTH-independent form, is linked to Carney's complex and autoantibodies targeting ACTH receptors.
• Accurate diagnosis is crucial, yet functional exploration of the HPA axis can yield misleading results in several clinical scenarios.

Outlook:

• Further research is needed to refine diagnostic strategies for complex and atypical Cushing's syndrome cases.
• Improved understanding of the pathophysiology of ectopic ACTH secretion and adrenal hyperplasia may lead to novel therapeutic approaches.
• Developing more specific diagnostic markers and imaging techniques is essential for accurate etiological determination.