[ACTH's ectopic secretion in a patient with precedents of Cushing's disease]

Area of Science:

• Endocrinology
• Oncology
• Internal Medicine

Background:

• Cushing's syndrome is a hormonal disorder caused by prolonged exposure to high cortisol levels.
• It can stem from pituitary adenomas (Cushing's disease) or ectopic sources of adrenocorticotropic hormone (ACTH).

Observation:

• A 54-year-old male with a 32-year history of Cushing's disease presented with edema, asthenia, and malaise.
• Laboratory findings revealed hypokalemia and metabolic alkalosis.
• A chest CT identified a 3x3 cm anterior mediastinal tumor, pathologically confirmed as thymic carcinoid.

Findings:

• The patient was diagnosed with biochemical Cushing's syndrome secondary to ectopic ACTH secretion from the thymic carcinoid.
• This represents a second, distinct episode of Cushing's syndrome in the same patient.

Implications:

• This case highlights the rare occurrence of dual Cushing's syndrome from different etiologies (pituitary and ectopic).
• It underscores the importance of considering ectopic ACTH sources in recurrent or atypical Cushing's syndrome presentations.
• This is the first reported instance of Cushing's syndrome caused sequentially by a pituitary adenoma and a thymic carcinoid.