Osteitis fibrosis cystica (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.

First described in the nineteenth century, OFC is currently detected through a combination of blood testing, X-rays, and tissue sampling.

[5] Generally, the presence of a palpable neck mass is also indicative of the cancer, occurring in approximately 50% of patients, but virtually nonexistent in individuals with OFC with a different origin.

Major mutations which can lead to hyperparathyroidism generally involve the parathyroid hormone receptor, G proteins, or adenylate cyclase.

[12] ESRD occurs when the kidneys fail to produce calcitriol, a form of vitamin D, which assists in the absorption of calcium into the bones.

[13] The concept of renal osteodystrophy is currently included into the broader term chronic kidney disease-mineral and bone disorder (CKD-MBD).

Modern dialysis takes pains to de-fluoridate water in order to minimize bone disease including OFC.

The 2006 National Research Council confirmed kidney patients are a sub-population particularly susceptible to ill effects from fluoride exposure which manifest in bones.

The effects of OFC on bone are largely dependent on the duration of the disease and the level of parathyroid hormone (PTH) produced.

It activates the parathyroid-hormone related protein receptor located on osteoclasts and osteocytes, both of which are responsible for the breakdown and maintaining of bone.

Abnormalities affecting the parathyroid glands cause a surplus of PTH, which, in turn, increases the activity and frequency of osteoclasts and osteocytes.

[29] Radiographs distinctly show bone resorption and X-rays of the skull may depict an image often described as "ground glass" or "salt and pepper".

[23] These cells are characteristically benign, feature a dense, granular cytoplasm, and a nucleus that tends to be ovular in shape, enclosing comparatively fine chromatin.

[35] In situations where parathyroid carcinoma is present, surgery to remove the tumors has also led to the regression of hyperparathyroidism as well as the symptoms of OFC.

Additionally, patients with OFC who have undergone parathyroidectomy begin to show regression of brown tumors within six months.

This results from a combination of suppressed parathyroid glands due to prolonged hypercalcaemia, as well as the need for calcium and phosphate in the mineralization of new bone.

[40] Thirty percent of patients with OFC-like tumors caused by metastatic parathyroid carcinoma who undergo surgery see a local recurrence of symptoms.

Parathyroid carcinoma accounts for less than 1% of all cases,[23] occurring most frequently in individuals around 50 years of age (in stark contrast to OFC as a result of primary hyperparathyroidism) and showing no gender preference.

[8] The condition was first described by Gerhard Engel in 1864 and Friedrich Daniel von Recklinghausen in 1890, though William Hunter, who died in 1783, is credited with finding the first example of the disease.

[47][48] "von Recklinghausen's disease" (without the qualification "of bone") is a completely unrelated disorder, nowadays termed neurofibromatosis.

Gustaf Retzius and Eugene Gley compounded his research, the latter credited with the discovery of the function of the parathyroid glands.

This increase led to a sharp decline in the prolonged manifestation of the disease, leading to a drop in the number of cases of OFC due to the early detection of hyperparathyroidism.