Endocrine Abstracts

Pheochromocytoma is a rare catecholamine-secreting tumour arising from chromaffin cells in the adrenal medulla and one of the main causes of endocrine hypertension. We here report the case of a 48-year old man admitted to the Internal Medicine Department for evaluation of resistant hypertension. The patient presented with headache, sweating, palpitations, pitting edema, hypertension and hypokalemia both resistant to conventional polytherapy. He was therefore investigated for endocrine causes of hypertension with evidence of urinary metanephrines above the upper reference limit. Besides, an abdominal CT scan showed a left adrenal mass highly suspicious for pheochromocytoma. Calcitonin and PTH levels were within the normal range. Further investigations showed high ACTH and blood cortisol levels. The latter remained unsuppressed after low-dose and high-dose dexamethasone suppression tests (1289 μg/l and 1302 μg/l, respectively). To rule out Cushing’s disease, a pituitary MRI was performed, without evidence of sellar abnormalities. All other anterior pituitary hormone levels were within the normal range, except for biochemical central hypothyroidism. The severe Cushing syndrome associated with hypokalemia along with the very high ACTH level (319 ng/l, normal values 7–63 ng/l) supported an ectopic source of ACTH. A total body CT scan confirmed only the previously known left adrenal mass lesion. The right adrenal gland was of normal appearance. The mass showed only selective enhancement in its caudal portion with 123I-MIBG scintigraphy, so a somatostatin receptor scintigraphy was performed which resulted positive. Treatment with metyrapone 250 mg every six hours and thyroxine replacement were initiated to control hypercortisolism and restore euthyroidism before surgery. After proper alfa- and beta-adrenoreceptor blockade treatment, a left adrenalectomy was performed. Hydrocortisone was given before and immediately after the operation, while cortisone acetate was employed afterwards. At two months follow-up, normalization of ACTH levels (24 ng/l) and urinary metanephrines was observed. Histopathology confirmed an ACTH-secreting pheochromocytoma associated with adrenal hyperplasia, with prevalence of the pars intermedia, with no signs of angio- or neuroinvasion nor necrosis, low mitotic index, no expression of SDHB and immunostaining positive for ACTH, synaptophysin, chromogranin A, GATA 3. Ectopic ACTH-production is most often related to small cell lung carcinomas or, rarely, to neuroendocrine carcinoids. Few cases of sporadic ACTH-producing adrenal-medullary tumours have been described. Despite its rarity, in those cases where hypertension is burdened by severe hypokalemia and hyperglycemia, an ACTH-secreting pheochromocytoma may be suspected. This condition should be excluded for its high mortality rate and since proper pre-operative management is essential.