Multiple brown tumors of the orbital walls: case report.

We report the case of a 40-year-old woman with chronic renal failure and secondary hyperparathyroidism that presented with slowly progressive proptosis of the right eye and mass sensation in the temporal and frontal orbital margins. Computerized tomography scan revealed two separate hyperdense and well-circumscribed lesions in the right orbital walls. A biopsy followed by histopathologic study revealed a dense lesion, with fibrous proliferation associated with osseous metaplasia and osteoclastic activity in the tumor, compatible with the diagnosis of brown tumor. The patient was submitted to surgical removal of the parathyroid glands that resulted in marked improvement in her condition and regression of the orbital tumors. Although the occurrence of more than one separate bone lesion in the orbit usually suggests metastasis, our case shows that brown tumors should also be included in the differential diagnosis of such lesions, particularly in patients with hyperparathyroidism.