Golgi Apparatus is an organelle in eukaryotic cells that stores and modifies proteins for specific functions and prepares them for transport to other parts of the cell. The Golgi apparatus is usually near the cell nucleus and consists of a stack of flattened sacs. Proteins secreted by the endoplasmic reticulum are transported into and across the Golgi apparatus by vesicles and may be combined with sugars to form glycoproteins. The modified products are stored in vesicles (such as lysosomes) for later use or transported by vesicles to the plasma membrane, where they are excreted from the cell.

A number of lesions that affect the jaws typically display multinucleated giant cells as one of their histopathologic components. Such a list would include infectious granulo-matous processes, response to exogenous material such as giant cell hyaline angiopathy, and benign neoplasm including osteoblastoma, cementoblastoma, juvenile active ossifying fibroma, chondroblastoma, chondromyxoid fibroma, and several malignant bone tumors. Additionally, several other entities occur in which giant cells are the predominant histologic finding and the basis for their recognition. This latter group of lesions, including central giant cell granuloma, giant cell tumor of bone, aneurysmal bone cyst, cherubism, and the brown tumor of hyperparathyroidism, is the focus of discussion in this book.