Cystic parathyroid adenoma

Osteitis fibrosa cystica ( OS-tee-AY-tis fy-BROH-sə SIS-tik-ə), is a skeletal disorder resulting in a loss of bone mass, a weakening of the bones as their calcified supporting structures are replaced with fibrous tissue (peritrabecular fibrosis), and the formation of cyst-like brown tumors in and around the bone. Osteitis fibrosis cystica, abbreviated OFC, also known as osteitis fibrosa, osteodystrophia fibrosa, and von Recklinghausen's disease of bone (not to be confused with von Recklinghausen's disease, neurofibromatosis type I), is caused by hyperparathyroidism, which is a surplus of parathyroid hormone from over-active parathyroid glands. [Source: Wikipedia ]