Unusual cause of hyercalcemia in pheochromocytoma
Venkata M R Katreddy, Khalid Ashawesh, Sanjay Saraf & Tarek M Fiad
Introduction: Hypercalcemia with pheochromocytoma usually occurs as part of MEN syndrome associated with parathyroid adenomas or hyperplasia. Here, we present a case of malignant pheochromocytoma with hypercalcemia caused by the secretion of PTHrP secretion tumour itself. Hypercalcemia was corrected on by the removal of the malignant pheochromocytoma.
Case: A 75-year-old gentleman with PMHx of hypertension presented with a history of fall and head injury due to postural hypotension. He also described weight loss for about 1 year. US abdomen showed left supra renal mass, followed by a CT abdomen and chest which confirmed a large 13.5/13.3/11.5 cm solid mass, with central necrosis and no obvious metastasis. Twenty-four urine collection showed raised urine normetadrenaline 142 μmol/24 (03.30), noradrenaline 11 737 nmol/24 h (100600), urine metadrenaline 3.03 μmol/24 h (01.20), urine adrenaline <10 nmol/24 h. Repeat urine samples consistently showed elevated noradrenalin and normetadrenaline. MIBG scan confirmed a left adrenal pheochromocytoma. During investigation was found to have elevated calcium on various occasions ranging from 2.72 to 3.23 mmol/l (2.12.6), phosphate 0.780.9 mmol/l (0.81.4), suppressed PTH <0.3. US parathyroid showed no adenomas or hyperplasia, bone scan did not reveal any metastatic disease. Measurement of PTHrP showed elevated 2.2 pmol/l (0.71.8). Patient underwent left adrenalectomy. Histology confirmed malignant pheochromocytoma with capsular invasion and vascular invasion, stains for chromogranin and synaptophysin, unfortunately not checked PTHrP staining. After surgery his calcium returned to normal 2.52 mmol/l, with PTH normal at 4.56 pmol/l and remained normal 18 months follow up.
Conclusion: Till now malignant pheochromocytoma with hypercalcemia secondary to PTHrP has been reported on only three occasions. This case illustrates a rare phenomenon of hypercalcemia with malignant phoechromocytoma due to humoral cause and not as part of MEN syndrome.