Osteitis fibrosa cystica mimicking bone tumor, a case report

Background We report a case of osteitis fibrosa cystica, a rare benign resorptive bone lesion caused by hyperparathyroidism, that presented on imaging as an aggressive bone tumor. Case presentation The patient is a 51-year-old male complaining of severe sustained pain of the right hip region. Imaging studies were suspicious for a malignant tumor of the right iliac bone. Biopsy under CT guidance was performed and showed remodeled bone trabeculae with numerous osteoclasts, excluding bone tumor and raising the possibility of osteitis fibrosa cystica. Complementary tests disclosed elevated blood level of parathyroid hormone and a partially cystic enlarged left inferior parathyroid gland consistent with adenoma. After parathyroidectomy, the clinical symptoms were relieved and the radiological findings were significantly improved, which confirmed the diagnosis. Conclusions Metabolic diseases-associated bone lesions should always be considered in the differential diagnosis of bone tumors, to avoid unnecessary surgeries and treatments.