Endocrine Abstracts (2003) 6 DP22

A Case of ACTH Secreting Benign Mediastinal Carcinoid with Hypocalcaemia

PA Goulden & MW Spring

Dept of Endocrinology & Diabetes, Kingston Hospital, Kingston-upon-Thames, UK.

This 42-year-old male presented with a six-month history of general lethargy and mood changes. He had experienced weakness & difficulty climbing stairs; weight loss; ankle swelling and increased frequency of micturition. There was no significant past medical history.

Initial investigations revealed Na+ 144mmol/L (135-145);K+ 2.3mmol/L(3.5-5.2); U 8.8mmol/L (2.6-6.7); Cr 75μmol/L (60-125); TCO2 41mmol/L (21-31); Fasting glucose 7.4mmol/L; TSH 0.21mU/L (0.35-4.5); Free T4 14.5 pmol/L (11.0-22.7); Corrected calcium 1.76mmol/L (2.12-2.62); Phosphate1.3mmol/L (0.8-1.5);

PTH 11.4pmol/L (0.5-5.5) & elevated 24hr urinary calcium

The overall biochemical picture was of a hypokalaemic alkalosis with hypocalcaemia and hyperglycaemia. A midnight cortisol was measured at 3046nmol/L and dexamethasone suppression testing revealed cortisol 2676 nmol/L with ACTH 275ng/L (10-50)

MRI Pituitary was normal. CT revealed bilaterally bulky adrenals.Petrosal sinus sampling revealed an inadequate central to peripheral ACTH ratio

The diagnosis was of ectopic ACTH dependent Cushing's. Following CT scan which was unsuccessful in locating the source; PET scanning & gated MRI revealed a lesion anterolateral to the right atrium in pericardial adipose tissue. He was referred to the cardiothoracic surgical team and a right atrial mass was resected via median sternotomy.

The final diagnosis was of benign anterior mediastinal carcinoid with histology also revealing thymic remnants. At follow up full cure had been achieved. The case is atypical in that the presentation was complicated by hypocalcaemia which was particularly profound.

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