ACTH-Secreting Pheochromocytoma with False-Negative ACTH Immunohistochemistry
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ACTH-Secreting Pheochromocytoma with False-Negative ACTH Immunohistochemistry Maria Francesca Cassarino & Alberto Giacinto Ambrogio & Luca Pagliardini & Martina De Martin & Valeria Barresi & Francesco Cavagnini & Francesca Pecori Giraldi
Published online: 27 May 2012 # Springer Science+Business Media, LLC 2012
Introduction Since 1955, when Roux [1] published the first association between pheochromocytoma and Cushing’s syndrome, we have come to appreciate the unique features of this unusual clinical entity. Pheochromocytoma represents a rare cause of hypercortisolism, accounting for less than 5 % of ectopic Cushing’s syndrome [2, 3] while less than 1 % of pheochromocytomas is accompanied by Cushing’s syndrome [4]. Pheochromocytomas are known to be heterogeneous, both functionally and clinically, a likely consequence of their ability to synthesize and secrete peptides in addition to catecholamine, such as vasoactive intestinal polypeptide, somatostatin, and calcitonin [5]. As regards hypothalamo– pituitary–adrenal axis peptides, both adrenocorticotropin (ACTH) and other proopiomelanocortin (POMC)-derived peptides [6, 7] as well as, occasionally, corticotropinreleasing hormone (CRH) [8] have been demonstrated in M. F. Cassarino : L. Pagliardini : M. De Martin : F. Cavagnini : F. Pecori Giraldi Neuroendocrinology Research Laboratory, Istituto Auxologico Italiano IRCCS, Milan, Italy A. G. Ambrogio : F. Pecori Giraldi Dipartimento di Scienze Mediche, University of Milan, Milan, Italy V. Barresi Dept Pathology, University of Messina, Messina, Italy F. Pecori Giraldi (*) University of Milan, Istituto Auxologico Italiano, piazzale Brescia 20, 20149 Milan, Italy e-mail: [email protected]
pheochromocytomas associated with ectopic Cushing’s syndrome. The diagnosis of ectopic Cushing’s syndrome is known to be fraught, as the most common cause of ACTHdependent hypercortisolism, i.e., pituitary Cushing’s disease, must first be excluded. This is accomplished by extensive diagnostic procedures, such as stimulation with CRH, suppression with high dose dexamethasone and inferior petrosal sinus sampling [9]. Imaging does not play a pivotal role in the diagnostic work-up as both pituitary and ectopic ACTH-secreting pituitary tumors may prove elusive and, conversely, false-positive imaging may lead to erroneous tumor localization [10–12]. The diagnosis of ectopic ACTH-secreting Cushing’s syndrome is therefore confirmed by remission of hypercortisolism after removal of the causative lesion and positive ACTH immunostaining in surgical specimens. We here present a thought-provoking ACTH-secreting pheochromocytoma with negative immunostaining for ACTH.
Methods Case Report A 69-year-old woman was referred for generalized weakness and fatigue, facial plethora, truncal obesity, slight striae rubrae, diffuse ecchimoses, leukocytosis (10.2×109/l WBC), severe hypertension, mild hypokalemia, and diabetes mellitus developed over the course of several months. Initial testing revealed ACTH-dependent hypercortisolism [urinary free cortisol, 409.7 μg
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