Mis-attribution of ectopic corticotropin-releasing hormone secretion (causing eutopic secondary adrenocorticotropic hormone secretion) to ectopic adrenocorticotropic hormone secretion?

摘要

Editor – In their Lesson-of-the month, 1 Kleinig and Russell describe acase of adrenocorticotropic hormone (ACTH)-dependent Cushing’ssyndrome, which they have ascribed to a metastatic small cellneuroendocrine carcinoma, presumed to have arisen throughde-differentiation of a prostate adenocarcinoma. They describethis as a case of ‘ectopic ACTH secretion’ both in the abstractand repeatedly in the main body of text. However, the completeabsence of any ACTH labelling in tumour tissue points towards thisdescription being both inaccurate and misleading. In the absenceof tumour-ACTH immunostaining, the actual ectopic hormonesecreted 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 caseof directly-secreted ectopic ACTH (as opposed to CRH) secretionby prostate adenocarcinomas. 2 Although the authors had noaccess to a CRH serum assay, nor CRH tissue immunolabelling,ectopic CRH secretion could easily have been confirmed at autopsythrough demonstration of corticotroph cell hyperplasia by ACTHimmunostaining of the pituitary gland itself.