Mis-attribution of ectopic corticotropin-releasing hormone secretion (causing eutopic secondary adrenocorticotropic hormone secretion) to ectopic adrenocorticotropic hormone secretion?
Editor – In their Lesson-of-the month,1 Kleinig and Russell describe a case of adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome, which they have ascribed to a metastatic small cell neuroendocrine carcinoma, presumed to have arisen through de-differentiation of a prostate adenocarcinoma. They describe this as a case of ‘ectopic ACTH secretion’ both in the abstract and repeatedly in the main body of text. However, the complete absence of any ACTH labelling in tumour tissue points towards this description being both inaccurate and misleading. In the absence of tumour-ACTH immunostaining, the actual ectopic hormone secreted was almost certainly corticotropin-releasing hormone (CRH), with ACTH being secreted eutopically in the pituitary gland. Lois et al reviewed the literature and identified no convincing case of directly-secreted ectopic ACTH (as opposed to CRH) secretion by prostate adenocarcinomas.2 Although the authors had no access to a CRH serum assay, nor CRH tissue immunolabelling, ectopic CRH secretion could easily have been confirmed at autopsy through demonstration of corticotroph cell hyperplasia by ACTH immunostaining of the pituitary gland itself.
- © Royal College of Physicians 2019. All rights reserved.
References
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- Kleinig P
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- Lois K
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