Osteitis Fibrosa Cystica Mistaken for Malignant Disease
A 65-year-old man who had severe back pain for one year was referred from a local orthopedic clinic to the department of oncology in our hospital, because plain radiographs showed multiple osteolytic lesions of the pelvis, femur and vertebrae (). Three years previously, he had a general physical examination showing no specific problems. However, one year ago, he was treated for a left femur fracture. The lumbar spine MRI showed that the vertebral bodies had low signal intensity due to osteoporosis, a compression fracture of the L2 spine and the L1 spinous process with a mass lesion; these findings were suggestive of bone metastasis or multiple myeloma (). The blood chemistry findings showed that the serum beta-2 microglobulin was 7,860 ng/mL (700-1,800) but the serum IgG, IgA, IgM and tumor markers were all negative and the serum protein electrophoresis and urine protein electrophoresis were negative for a monoclonal gammopathy. However, the alkaline phophatase was 6,788 IU/L (40-250), total calcium was 12.8 mg/dL (8.2-10.5), ionized calcium was 6.5 pg/mL (4.3-5.0) and the PTH was 1,889 pg/dL (0-65). The chest X-ray showed diffuse osteoblastic and some osteolytic lesions of the bony thorax. The bone mineral density studies of the spine and femur were consistent with osteoporosis. The computed tomography (CT) of the abdomen and pelvis demonstrated parenchymal calcinosis of the liver and medullary calcinosis of both kidneys. The entire skeleton had diffuse osteoblastic and osteolytic lesions. The fludeoxyglucose-positron emission tomography (FDG-PET) showed multiple areas of FDG uptake in the bones consistent with the pattern of bony metastasis from a malignancy; however, we could not identify a primary lesion ().\nThe fine needle aspiration biopsy from the L1 spinous mass revealed reactive fibroblastic tissue with scattered multinucleated giant cells, and hemorrhage suggestive of osteitis fibrosa cystica. The neck CT scan showed a well enhanced mass at the posteroinferior site of the right thyroid gland (), and the parathyroid Tc-99m sestamibi scan also showed increased uptake at the same site (). Because the serology and imaging tests were only suggestive of hypercalcemia due to hyperparathyroidism, the patient was referred to the ENT department where the diagnosis of primary hyperparathyroidism with osteitis fibrosa cystica due to a parathyroid tumor was considered. We planned to perform parathyroidectomy. Prior to the surgery, the radiating pain to the right leg, due to the compression fracture of the L-spine, worsened and emergency surgery was performed to remove the mass lesion in addition to a L2-T12 fusion.\nThe histopathological findings reported from the mass lesion were consistent with osteitis fibrosa cystica (). Next, a minimally invasive parathyroidectomy was performed using intraoperative PTH monitoring techniques. We found an enlarged parathyroid in the posteroinferior portion of the right thyroid and one additionally enlarged gland that was not detected on the preoperative imaging studies. The serology showed that the total calcium, ionized calcium, and PTH recovered to within normal range on postoperative day 1. However, on postoperative day 2, the patient developed the hungry bone syndrome (total calcium was 6.5, ionized calcium was 3.9 and serum phosphorus was 2.1). We conlsuted endocrinology department for this problem, and it resolved with vitamin D and calcium replacement within 2 weeks. The histopathological diagnosis was parathyroid hyperplasia affecting two glands.