Myeloid Or Giant-Celled Sarcoma (Fig. 101) is a tumour in which the giant-cell is characteristic, but never forms the only sarcomatous element, there being generally spindle cells and sometimes round cells in great abundance. The giant-cells are in greater or smaller number in proportion to the others, and in the same tumour they may present various proportions in different parts. The tumour tissue is soft, and very often of a brown colour. Cysts not infrequently develop by softening.

Spindle celled sarcoma of tibia growing from upper end of diaphysis.

Fig. 99. - Spindle-celled sarcoma of tibia growing from upper end of diaphysis. It is eroding the bone.

Large fungating spindle celled sarcoma of the foot.

Fig. 100. - Large fungating spindle-celled sarcoma of the foot. (Virchow).

The myeloid sarcoma occurs in connection with bone, and most frequently grows from the medulla. This is especially the case with the long bones, where the tumours originate in the cancellated tissue at the extremity - the most usual situation being the lower end of femur or upper end of tibia. (See under Diseases of Bone).

Myeloid sarcoma is also met with outside bones, growing from the periosteum, especially of the jaws.

Many tumours, to which the name Epulis is given, are myeloid sarcomas.

The myeloid sarcoma is, for the most part, slow of growth, and does not usually produce secondary tumours.

Giant celled sarcoma, x 175.

Fig. 101. - Giant-celled sarcoma, x 175.