CHALLENGING CASE OF PHEOCHROMOCYTOMA WITH ELEVATED CALCITONIN LEVEL

Abstract

Pheochromocytoma, or adrenal paraganglioma, is a neuroendocrine tumor of the adrenal medulla. In the vast majority of cases, pheochromocytoma is a hormonally active tumor with hypersecretion of catecholamines: adrenaline, norepinephrine, dopamine. However, due to the neuroendocrine origin of the tumor, extremely rare cases of ectopic hypersecretion of other peptide hormones by pheochromocytoma have also been described, such as adrenocorticotropic hormone, somatostatin, neuropeptide Y, methenkephalin, and vasoactive interstitial peptide. In the available literature in Russian and English, we found only four cases of calcitonin secretion by pheochromocytoma, the earliest of which was published in 1977. Examination of a 38-year-old female patient with hypertension (chronically high blood pressure involved sympathoadrenal crises with vegetative dysfunction) revealed a large tumor of the right adrenal gland up to 78 mm. Detailed radiation characteristics of the tumor by ultrasound, computed tomography (CT), magnetic resonance imaging, and positron emission tomography with CT with 18-fluorodeoxyglucose were presented. The results of laboratory tests established hyperproduction of catecholamines by the tumor. In addition, a repeated increase in the level of calcitonin in the blood was revealed, which, in the absence of a genetic study of the RET proto-oncogene, did not allow to exclude the multiple endocrine neoplasia (MEN) type 2. After surgical treatment, the level of calcitonin in the blood decreased to undetectable, which suggested hyperproduction of calcitonin by pheochromocytoma. This hypothesis was confirmed by the results of histological and immunohistochemical studies of the surgical material. Ectopic production of calcitonin by pheochromocytoma is not typical and is extremely rare, but its development is possible, which should be taken into account when observing its elevated level in patients with pheochromocytoma. Preoperative genetic testing in such cases may significantly reduce the risk of developing medullary thyroid carcinoma in patients without hereditary MEN2.