Endocrine Abstracts

Brown tumors (BT) consist of focal bone lesions, caused by increased osteoclastic activity and fibroblastic proliferation. They appear in chronic kidney disease (CKD) as a result of renal osteodystrophy with high bone turnover, due to secondary hyperparathyroidism. BT are composed of mononuclear stromal cells mixed with multinucleated giant cells and hemosiderin deposits, which give the characteristic brown colour. We present the case of a 13-year-old girl, with end-stage CKD on peritoneal dialysis for 3 years, who accused important retroauricular pain with right hemifacial oedema and right retroauricular tumefaction. The cranio-cerebral CT shows a 3.6/2.4/1.6cm polylobate mastoidian tumor. The cervical US shows two homogenous hypoechoic nodules at the lower poles of the thyroid gland. Biologically there was severe vitamin D deficiency 4.7 ng/ml, mildly elevated parathormone levels 180 pg/ml, hypercalcemia and hyperphosphoremia, sugesstive of tertiary hyperparathyroidism. Total parathyroidectomy with subsequent parathyroid tissue transplantation in the left sternocleidomastoidian muscle was performed. Two months following surgery, a significant reduction in tumor volume was observed, the retroauricular region having a quasi-normal normal appearance. Clinically significant brown tumors in the pediatric population are uncommon and may mimic malignant lesions of the bone. Choosing between medical and surgical management may be challenging, due to the rarity of the tumor and lack of existing data. The effective control of hyperparathyroidism will often lead to tumor regression and calcification.

Keywords: brown tumor, chronic kidney disease, hyperparathyroidism