Multiple Focal Brown Tumors (Osteitis Fibrosa Cystica) in a Renal Transplant Recipient.

Brown tumors (BTs) are manifestations of osteitis fibrosa cystica that develops due to increased osteoclast activity secondary to hyperparathyroidism (HPTH). The name comes from its characteristic brown color due to high hemosiderin level and hemorrhage surrounded by osteoclastic giant cells, fibrous tissue, and bone fragments. Presentation can be either unifocal or rarely multifocal. Misdiagnosis of BT compared to malignant giant cell tumor is not uncommon. Early diagnosis and intervention may prevent destructive bone changes. Treatment of BTs due to chronic renal failure should be aimed primarily at its prevention with phosphate binders, vitamin D (analogues), calcimimetics, and prolonged dialysis sessions. Parathyroidectomy can be the option in nonresponsive cases. In this report, we present an unusual case of multiple brown tumors in a 54-year-old female renal transplant patient involving the spine, jaw, and scapula, initially misdiagnosed as giant cell tumor. Five years later, the patient was diagnosed with BT because of the medical history, morphology, and negative p63 staining in combination with secondary/tertiary hyperparathyroidism. The patient subsequently underwent subtotal parathyroidectomy.