A Case Report of a Giant Parathyroid Adenoma Presenting with a Brown Tumor;Required Differentiation from Parathyroid Carcinoma

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Background: Giant parathyroid adenoma presenting with a brown tumor is considered to be rare. This conditionrequires special consideration.Case Presentation: A 21-year-old woman presented to the clinic with persistent pain in her right knee. A radiographic examination showed an osteolytic lesion in her right tibia. Blood laboratory tests revealed that serumcalcium and intact parathyroid hormone were increased significantly. Physical examination showed a 3-cm, firm,immovable lump in her neck. Ultrasonography of the patient’s neck revealed a 3.5-cm, well-circumscribed masswith a homogeneous internal texture. Computed tomography also showed a localized tumor with clear margins.The 99mTc-MIBI scintigraphy showed a hot spot in the right inferior gland. Based on these findings we judgedthat she had giant parathyroid adenoma presenting with a brown tumor. These pre-operative findings suggest thatthe possibility of carcinoma was low. We performed a parathyroidectomy via a small incision. The excised parathyroid gland weighed 10.3 g. The patient’s postoperative course was unremarkable.Conclusions: Giant parathyroid adenoma presenting with a brown tumor is rare. Accordingly, the differentiationbetween giant adenoma and parathyroid carcinoma is crucial. However, we determined that the possibility ofcarcinoma was low based on imaging studies, including ultrasonography and computed tomography. As a result,we performed successful parathyroidectomy with a small incision.