Problems arise in separating these diseases when fibrous dysplasia only affects the jaw. This is a tumour of bone but rarely affects the jaw. It usually involves the long bones of the leg of men in their twenties to forties. GCT is not a disease familial. The histology of Cherubism and GCT can be virtually identical.
Hyperparathyroidism is a disease in which patients have too much parathyroid hormone.
However, unlike Cherubism, which is restricted largely to the jaw, hyperparathyroidism affects many of the bones in the body. Hyperparathyroidism can be diagnosed by measuring high levels of parathyroid hormone in the blood. These are two different diseases which have several things in common but some aspects of the disease are quite different. This can lead to problems in separating the two diseases. These are usually picked up by x-ray.