Unusual clinical presentation of brown tumor in hemodialysis patients: two case reports.

Brown tumor or osteoclastoma is a lytic bone tumor, which is common in secondary hyperparathyroidism (1.5-13%) in chronic dialysis patients, mainly in those with untreated renal osteodystrophy. Brown tumor appears as a result from excess osteoclast activity and consists of collections of osteoclasts intermixed with fibrous tissue and poorly mineralized woven bone. It can be manifested as a single or multiple bone lesions. Although invasive, it has no malignant potential and should be distinguished from giant cell tumors of the bone. Two unusual cases of brown tumor in dialysis patients are reported. We present a first patient with five subtotal parathyroidectomies between 2002 and 2009 and a tendency toward recurrence of secondary hyperparathyroidism (sHPTH). The double MRI check up could not reveal any ectopic parathyroid gland. Although the patient had permanently high PTH values, serum calcium level was never above the normal range. However, the brown tumor in the cervical spine was destructing the cervical vertebrae and required surgical intervention. Despite the conservative treatment with calcium and non-calcium-based binders and various forms of vitamin D, the patient's clinical and biochemical condition improved only after the use of cinacalcet. The second patient, a 58-years-old female on chronic hemodialysis since 1998, was found with high PTH serum levels in 2009. The development of sHPTH was scintigraphically confirmed and surgically treated. During the late 2008, she started feeling pain, numbness and swelling of the 3rd right hand finger, prior to the full clinical manifestation of the tumor. The CT scan of the right hand showed osteolytic changes and soft tissue destruction of the middle phalanx of the 3rd right hand finger. This formation corresponded to an unusual presentation of brown tumor associated with sHPTH. As expected, after the parathyroidectomy, there was no marked change in the destructed bone of the 3rd right hand finger middle phalanx, but only a gradual improvement in the subjective clinical condition of the patient. Based on these two reports, we would recommend that in cases of severe or recurrent sHPTH either total parathyroidectomy or early administration of calcimimetics should be considered. Furthermore, the implementation of regular checkup and treatment according to the KDIGO guidelines should be advised and clinical appearance of any bone tumor immediately checked for an association with sHPTH, which is a rather common entity in dialysis patients.