Brown tumor and secondary hyperparathyroidism.

Brown tumor is a focal, bony lesion of hyperparathyroidism that results from parathyroid hormone on bone increasing osteoclastic activity with bone resorption and trabecular fibrosis. This leads to microfractures and hemorrhage and the appearance of brown tumors, which are seen most commonly in primary hyperparathyroidism and less frequently in secondary hyperparathyroidism. Rarely do these tumors involve the orbit. We report the sixth case, to our knowledge, of orbital involvement, in a patient with chronic renal failure (secondary hyperparathyroidism) and review the literature.