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Open access

Regina Streuli, Ina Krull, Michael Brändle, Walter Kolb, Günter Stalla, Marily Theodoropoulou, Annette Enzler-Tschudy and Stefan Bilz

Summary

Ectopic ACTH/CRH co-secreting tumors are a very rare cause of Cushing’s syndrome and only a few cases have been reported in the literature. Differentiating between Cushing’s disease and ectopic Cushing’s syndrome may be particularly difficult if predominant ectopic CRH secretion leads to pituitary corticotroph hyperplasia that may mimic Cushing’s disease during dynamic testing with both dexamethasone and CRH as well as bilateral inferior petrosal sinus sampling (BIPSS). We present the case of a 24-year-old man diagnosed with ACTH-dependent Cushing’s syndrome caused by an ACTH/CRH co-secreting midgut NET. Both high-dose dexamethasone testing and BIPSS suggested Cushing’s disease. However, the clinical presentation with a rather rapid onset of cushingoid features, hyperpigmentation and hypokalemia led to the consideration of ectopic ACTH/CRH-secretion and prompted a further workup. Computed tomography (CT) of the abdomen revealed a cecal mass which was identified as a predominantly CRH-secreting neuroendocrine tumor. To the best of our knowledge, this is the first reported case of an ACTH/CRH co-secreting tumor of the cecum presenting with biochemical features suggestive of Cushing’s disease.

Learning points:

  • The discrimination between a Cushing’s disease and ectopic Cushing’s syndrome is challenging and has many caveats.
  • Ectopic ACTH/CRH co-secreting tumors are very rare.
  • Dynamic tests as well as BIPSS may be compatible with Cushing’s disease in ectopic CRH-secretion.
  • High levels of CRH may induce hyperplasia of the corticotroph cells in the pituitary. This could be the cause of a preserved pituitary response to dexamethasone and CRH.
  • Clinical features of ACTH-dependent hypercortisolism with rapid development of Cushing’s syndrome, hyperpigmentation, high circulating levels of cortisol with associated hypokalemia, peripheral edema and proximal myopathy should be a warning flag of ectopic Cushing’s syndrome and lead to further investigations.
Open access

Harish Venugopal, Katherine Griffin and Saima Amer

Summary

Resection of primary tumour is the management of choice in patients with ectopic ACTH syndrome. However, tumours may remain unidentified or occult in spite of extensive efforts at trying to locate them. This can, therefore, pose a major management issue as uncontrolled hypercortisolaemia can lead to life-threatening infections. We present the case of a 66-year-old gentleman with ectopic ACTH syndrome from an occult primary tumour with multiple significant complications from hypercortisolaemia. Ectopic nature of his ACTH-dependent Cushing's syndrome was confirmed by non-suppression with high-dose dexamethasone suppression test and bilateral inferior petrosal sinus sampling. The primary ectopic source remained unidentified in spite of extensive anatomical and functional imaging studies, including CT scans and Dotatate-PET scan. Medical adrenolytic treatment at maximum tolerated doses failed to control his hypercortisolaemia, which led to recurrent intra-abdominal and pelvic abscesses, requiring multiple surgical interventions. Laparoscopic bilateral adrenalectomy was considered but decided against given concerns of technical difficulties due to recurrent intra-abdominal infections and his moribund state. Eventually, alcohol ablation of adrenal glands by retrograde adrenal vein approach was attempted, which resulted in biochemical remission of Cushing's syndrome. Our case emphasizes the importance of aggressive management of hypercortisolaemia in order to reduce the associated morbidity and mortality and also demonstrates that techniques like percutaneous adrenal ablation using a retrograde venous approach may be extremely helpful in patients who are otherwise unable to undergo bilateral adrenalectomy.

Learning points

  • Evaluation and management of patients with ectopic ACTH syndrome from an unidentified primary tumour can be very challenging.
  • Persisting hypercortisolaemia in this setting can lead to debilitating and even life-threatening complications and hence needs to be managed aggressively.
  • Bilateral adrenalectomy should be considered when medical treatment is ineffective or poorly tolerated.
  • Percutaneous adrenal ablation may be considered in patients who are otherwise unable to undergo bilateral adrenalectomy.

Open access

Julien Ducry, Fulgencio Gomez, John O Prior, Ariane Boubaker, Maurice Matter, Matteo Monti, Yan Pu, Nelly Pitteloud and Luc Portmann

Summary

Ectopic ACTH Cushing's syndrome (EAS) is often caused by neuroendocrine tumors (NETs) of lungs, pancreas, thymus, and other less frequent locations. Localizing the source of ACTH can be challenging. A 64-year-old man presented with rapidly progressing fatigue, muscular weakness, and dyspnea. He was in poor condition and showed facial redness, proximal amyotrophy, and bruises. Laboratory disclosed hypokalemia, metabolic alkalosis, and markedly elevated ACTH and cortisol levels. Pituitary was normal on magnetic resonance imaging (MRI), and bilateral inferior petrosal sinus blood sampling with corticotropin-releasing hormone stimulation showed no significant central-to-periphery gradient of ACTH. Head and neck, thoracic and abdominal computerized tomography (CT), MRI, somatostatin receptor scintigraphy (SSRS), and 18F-deoxyglucose-positron emission tomography (FDG-PET) failed to identify the primary tumor. 18F-dihydroxyphenylalanine (F-DOPA)-PET/CT unveiled a 20-mm nodule in the jejunum and a metastatic lymph node. Segmental jejunum resection showed two adjacent NETs, measuring 2.0 and 0.5 cm with a peritoneal metastasis. The largest tumor expressed ACTH in 30% of cells. Following surgery, after a transient adrenal insufficiency, ACTH and cortisol levels returned to normal values and remain normal over a follow-up of 26 months. Small mid-gut NETs are difficult to localize on CT or MRI, and require metabolic imaging. Owing to low mitotic activity, NETs are generally poor candidates for FDG-PET, whereas SSRS shows poor sensitivity in EAS due to intrinsically low tumor concentration of type-2 somatostatin receptors (SST2) or to receptor down regulation by excess cortisol. However, F-DOPA-PET, which is related to amine precursor uptake by NETs, has been reported to have high positive predictive value for occult EAS despite low sensitivity, and constitutes a useful alternative to more conventional methods of tumor localization.

Learning points

  • Uncontrolled high cortisol levels in EAS can be lethal if untreated.
  • Surgical excision is the keystone of NETs treatment, thus tumor localization is crucial.
  • Most cases of EAS are caused by NETs, which are located mainly in the lungs. However, small gut NETs are elusive to conventional imaging and require metabolic imaging for detection.
  • FDG-PET, based on tumor high metabolic rate, may not detect NETs that have low mitotic activity. SSRS may also fail, due to absent or low concentration of SST2, which may be down regulated by excess cortisol.
  • F-DOPA-PET, based on amine-precursor uptake, can be a useful method to localize the occult source of ACTH in EAS when other methods have failed.