Endocrine Abstracts

Case history: Cyclical Cushing’s is a very rare disease with rhythmic fluctuations in cortisol production with or without phenotypic features. It is a very challenging entity to diagnose. The low index of clinical suspicion is key for timely diagnosis and prevention of long-term complications. A 66 years old male presented with intermittent, episodic bilateral leg swelling and reversible weight gain of ˜6 kg following these episodes. Background history entailed femoral patella replacement and atrial tachycardia. Examinations reveal bilateral leg swelling and pitting edema up to the mid-shin level. There was no evidence of proximal myopathy or easy bruising. Routine biochemistry and baseline investigations including BNP, urine PCR/ACR/VEGF and echocardiography were normal. BP was 142/87 mmHg. The possibility of cyclical Cushing’s syndrome was considered. He had a normal previous urine free cortisol by GP, all biochemistry repeated while being symptomatic.

Investigations: ONDST: post-test cortisol 92 nmol/l, ACTH 61.1 ng/l (reference range 0–46 ng/l).

LDDST: post-test cortisol of 123 nmol/l.

24 h UFC: 4129 nmol/24 h.

Volumetric MRI pituitary: 2 mm right-sided pituitary lesion.

FDG PET: normal FDG-avidity.

IPSS: Baseline ACTH central to peripheral ratio of 5.05. Left inferior petrosal sinus 327 ng/l, peripheral 64.7 ng/l, left to right ratio of 3.17 at baseline suggesting left lateralization. There was minimal response to CRH.

Treatment: Following MDT discussion, he underwent trans-sphenoidal hypophysectomy. His postoperative 0900 h cortisol was ˜600–800 nmol/l. Post-redo completion trans-sphenoidal hypophysectomy at day-7 cortisol levels were 290 mmol/l. Histology did not show any evidence of ACTH secreting adenoma. He developed postoperative hypopituitarism including DI, hypothyroidism and hypogonadism. He was commenced on replacement including Nebido 1 g every 12 weeks, Levothyroxine 75 mcg, Desmopressin 100/100/300 mcg. His Cushing’s remained active. He was commenced on the block and replace regimen with Metyrapone and prednisolone, metyrapone titrated on the basis of metyrapone–hydrocortisone day curve data. Adjuvant cabergoline was poorly tolerated. He received radiotherapy 45 Gy in 25 fractions for 28 days, using a 6-MV X-ray technique. Repeat imaging showed no evidence of recurrence. 11-C methionine PET imaging has been requested to consider the possibility of targeted therapy. Also discussed consideration of adrenalectomy if radiotherapy proves unsuccessful

Discussion points: Our case presents the opportunity to discuss the challenges in the diagnosis and treatment of cyclical Cushing’s, new emerging therapies for Cushing’s disease, pros and cons of adrenalectomy versus radiotherapy, and the role of methionine 11-C methionine PET imaging in the detection of ACTH-secreting tumors in ACTH-dependent Cushing's syndrome with facilitation of targeted therapy.