Endocrine Abstracts

A 51-year-old obese lady was admitted with multiple cerebral, pulmonary and intra-abdominal abscesses. She was referred to the endocrine team because of newly-diagnosed type 2 diabetes mellitus. The combination of apparent immunosuppression, obesity, diabetes mellitus, hypertension, hypokalaemia, osteoporotic fractures and bilateral shoulder avascular necrosis (BSAN) led to a clinical diagnosis of Cushing’s syndrome (CS); this was biochemically confirmed as follows: non-suppressed overnight dexamethasone suppression test, midnight serum cortisol 4275 nmol/l (60–250), raised salivary cortisol 716 nmol/l (5–46) and ACTH 639 ng/l (0–46). Urinary free cortisol (UFC) was elevated in excess of 75 000 nmol/l (<165). Urinary steroids metabolites were markedly increased: tetrahydrocortisol 219 024 μg/24 h and tetrahydrocortisone 88 848 μg/24 h. Pituitary MRI was unremarkable. Whole body CT scanning showed a thymic tumour and bilateral adrenal hyperplasia. Octreotide scanning showed increased focal activity in the thymus. Urinary 5HIAA was only marginally raised at 55 μmol/24 h (<45 μmol/24 h) and chromogranin A was normal: 52 pmol/l (<60 pmol/l).

Infections followed a protracted course, despite treatment with antibiotics and antifungal agents. She received metyrapone prior to a thymectomy. Histology confirmed a ‘paraganglioid’ variant of a thymic carcinoid tumour. Post-operatively she displayed remarkable clinical and biochemical recovery, but poorly controlled diabetes, hypertension, obesity and BSAN continued to be active problems.

We describe a case of ACTH-secreting thymic carcinoid that presented with florid clinical features of CS, but no carcinoid syndrome. Profoundly elevated cortisol concentrations were observed in saliva, serum and urine (all measured using LC–MS/MS), with loss of diurnal variation. Indeed, UFC is the highest that has ever been described for ectopic CS. Contrary to conventional investigation algorithms, IPSS was not necessary to confirm the diagnosis; instead, the combination of markedly elevated ACTH, cortisol, cortisol metabolites coupled with a negative MR pituitary and a positive CT thorax and octreotide scan were sufficient to make an accurate diagnosis.