ESA-SRB-AOTA 2019

A challenging case of an ectopic ACTH-producing tumour (#624)

Kirsten Neal 1 , Ann McCormack 1
  1. Endocrinology, St Vincent's Hospital, Sydney, NSW, Australia

Bronchial carcinoid tumours are very rare tumours but are the most common tumour associated with ectopic ACTH production leading to Cushing’s syndrome. If feasible, the mainstay of treatment is surgical resection, granted the tumour is locatable. We present a case of a 26-year-old male with Cushing’s syndrome who had a difficult-to-locate bronchial carcinoid tumour. Investigations including high-dose dexamethasone suppression test, inferior petrosal sinus sampling and CRH stimulation were suggestive of ectopic ACTH production. CT and SPECT/CT revealed no tumours and MRI pituitary showed a 3.5mm lesion consistent with microadenoma. 68Ga-DOTATE-PET/CT demonstrated mild DOTATATE avidity in a small right hilar lymph node, most consistent with inflammation. Endoscopic bronchial ultrasound was not feasible. All investigations were performed in a tertiary centre with pituitary specialisation.  The primary tumour was seemingly unidentifiable and the patient underwent transsphenoidal exploration which was non curative; histopathology revealing a Rathke’s cleft cyst. The patients' Cushing's syndrome continued to worsen and after repeat investigations a cardiothoracic surgeon explored the right hilar inflammatory lesion with a mini-thoracotomy, revealing low grade neuroendocrine tumour in four of sixteen lymph nodes; the primary tumour still not identified. Post-operatively the patient experienced partial recovery lasting several months but soon his symptoms worsened and cortisol levels rose again. Medical treatment was commenced. Eighteen months post mini-thoracotomy a repeat 68Ga-DOTATE-PET/CT identified a subtle right upper lobe lung lesion leading to a second, albeit difficult, thoracotomy where the primary tumour was resected. This resulted in a dramatic improvement in the patient’s symptoms and cortisol levels.  This case highlights the difficulty that often arises trying to locate ectopic ACTH producing tumours and that when high quality investigations have been performed the results should be taken with great heed.