Endocrine Abstracts

Introduction: Cyclic Cushing syndrome (CCS) involves rhythmic fluctuations in ACTH secretion resulting in a cyclic variation of adrenal steroid production.

Case presentation: A 37-year-old woman was referred to our Pituitary Clinic in 1999, for evaluation of galactorrhea and irregular menses that had started four months ago. She also complained of depression, facial hirsutism, alopecia and progressive obesity. Blood pressure was normal. Endocrinological evaluation revealed prolactin blood level elevated twice and a half the reference value, low gonadotrofins blood values, and urinary free cortisol (UFC) of 166.1 μg/24 h (reference: 28.5–214). The cerebral magnetic resonance imaging suggested a non-functioning pituitary macroadenoma without optic quiasm compression. Two years later, tumor dimensions were unchanged and UFC remained normal (50.6) but without cortisol circadian rhythm. One year later, she was admitted with diabetic ketoacidosis and 1 month later, insulin was suspended because of frequent hypoglycemias. Shortly thereafter, she was readmitted because of vomiting, metabolic alkalosis and hypokalemia. Four months later, basal UFC was 387.8 and ACTH was 128 pg/ml (reference: <46), with a paradoxical response to the high dose dexamethasone supression test. Despite medical advice, she left the country before pituitary surgery. Three years later, she returned to our Clinic and normal UFC and ACTH were observed. Surgery was performed in 2007 and immunochemistry revealed diffuse positive ACTH tumor staining.

Discussion: One of the proposed explanations for the mechanism behind the CCS of pituitary origin is the occurrence of spontaneous, episodic haemorrhage in the tumor with temporary damage of the actively secreting cells. CCS should be strongly suspected in patients with signs or symptoms of hypercortisolism but normal cortisol levels and paradoxical responses to the dexamethasone test.