Answer: Brown tumor of hyperparathyroidism

Histology: The eye-catching feature on microscopic examination is the multinucleated giant cells. They are abundantly present. They are osteoclast-like in their appearance having an abundant cytoplasm that houses up to 100 nuclei. The multinucleated giant cells are interspersed among spindled to oval mononuclear cells. Secondary background features include hemorrhage, hemosiderin deposition, chronic inflammation and islands of metaplastic bone.

Discussion: There are a handful of giant cell rich lesions of the craniofacial bones that demonstrate similar microscopic features – namely, the accumulation of multinucleated giant cells within a vascular and proliferative fibroblastic background. These include central giant cell granuloma, brown tumor of hyperparathyroidism, and cherubism. Thus, the radiographic features and clinical findings are essential when it comes to sorting out the various giant cell-rich lesions of the craniofacial bones. This particular patient has long term end stage renal disease with secondary hypertension. Accordingly, the changes are consistent with a Brown Tumor of Hyperparathyroidism.