Giant cell tumour (osteoclastoma) of the pancreas--an epithelial tumour probably of pancreatic acinar origin.

A case of giant cell tumour of the pancreas has been studied. The light microscopical appearance of the tumour is indistinguishable from osteoclastoma of bone. Electron microscopy of the tumour shows many typical desmosomes between stromal cells. This is strong evidence of its epithelial nature. The cytoplasm of both the osteoclast-like giant cells and stromal cells contain abundant rough endoplasmic reticulum, many with dilated cisternae containing prominent dense granules. There are also some larger homogeneous granules, some of them electron-dense, in the cytoplasm of the cells. These findings when compared with the features of other cases of giant cell tumour of the pancreas studied by electron microscopy support the view that this epithelial tumour is of acinar origin.