Poster Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

A Cushing's conundrum (#605)

Rose Lin 1 , Mark Savage 1 , Amy Harding 1
  1. Endocrinology, Bendigo Health, Bendigo, VIC, Australia

We present the case of a multimorbid 49-year-old female admitted with atraumatic rib fractures, who was found to have an 38mm left adrenal incidentaloma. Screening tests revealed elevated serum cortisol and adrenocorticotrophic hormone (ACTH) levels. The serum cortisol did not suppress following administration of 1mg dexamethasone, consistent with a diagnosis of ACTH-dependent Cushing’s syndrome. Pituitary magnetic resonance imaging was normal, and an 8mg dexamethasone suppression test supported the impression of ectopic ACTH syndrome. Full body computed tomography imaging showed no obvious source of ACTH production. A GaTATE position emission tomography (PET) scan reviewed a 14mm right infrahilar lung nodule with mild-moderate GaTATE avidity. This lesion was not avid on FDG PET imaging, consistent with a neuroendocrine tumour of the lung. During work up of the Cushing’s syndrome, the patient developed an atraumatic femoral neck fracture, so medical treatment with ketoconazole was commenced. The initial response was excellent. However, control was not sustained, with persistent hypercortisolism despite increasing doses of ketoconazole, so treatment was switched to osilodrostat. The main dilemma was inability to confirm the diagnosis of the lung lesion with tissue biopsy, due to difficulty accessing the lesion because of its anatomical location, and high surgical risk. Multidisciplinary and interhospital discussions suggested that biopsy may be achieved via endobronchial ultrasound (EBUS), which is pending. Our primary differential is an ectopic ACTH-secreting bronchial carcinoid. Ectopic ACTH syndrome is rare, accounting for 5-10% of all ACTH-dependent Cushing’s syndrome (1). It can be extremely difficult to localise, with 19% of ACTH-secreting tumours remaining occult despite extensive investigation in one study (2). The best treatment is surgical resection of the tumour prior to metastasis (1, 3), which is curative of both the malignancy and Cushing’s syndrome. Non-surgical treatment options depend on the underlying tumour histology. We eagerly await the result of the EBUS.

 

  1. 1. Hayes AR, Grossman AB. The Ectopic Adrenocorticotropic Hormone Syndrome: Rarely Easy, Always Challenging. Endocrinol Metab Clin North Am. 2018;47(2):409-25.
  2. 2. Isidori AM, Sbardella E, Zatelli MC, Boschetti M, Vitale G, Colao A, et al. Conventional and Nuclear Medicine Imaging in Ectopic Cushing's Syndrome: A Systematic Review. J Clin Endocrinol Metab. 2015;100(9):3231-44.
  3. 3. Melosky B. Advanced typical and atypical carcinoid tumours of the lung: management recommendations. Curr Oncol. 2018;25(Suppl 1):S86-s93.