Aneurysmal bone cyst and other nonneoplastic conditions.

Aneurysmal bone cyst is a benign proliferative tumefaction of bone. Histologic similarities indicate a kinship among classic aneurysmal bone cysts, essentially "solid" proliferative lesions in bones; giant cell reparative granulomas of the jaws, at the base of the skull, and in the small bones of the hands and feet; skeletal lesions of hyperparathyroidism; and even pseudosarcomatous myositis ossificans, proliferative myositis, and proliferative fasciitis.