Round-Cell Sarcomata are those made up of either large or small round cells.

In the small-cell variety the intercellular substance is very scanty. They are rather soft, whitish in color, friable, and a milky juice can be scraped from the cut surface.

Fig. 41. - Giant-cell Sarcoma of the Thigh (McFarland). a, Giant cells; b, spindle cells.

They grow rapidly, infiltrate the surrounding tissues, give extensive metastasis, recur quickly after removal, and soon cause death. They may occur in any part of the body and at any age.

The individual cells have large vesicular nuclei, that stain deeply, and comparatively little protoplasm.

If there is a close resemblance to the arrangement of a lymphnode, small round cells with a distinct reticulum, the tumor is called a lymphosarcoma.

The large round-cell sarcoma is very similar to the small, but is firmer on account of the intercellular connective tissue present. The cells are larger, and although generally round, may be polygonal, and are sometimes arranged in alveoli.

Are less malignant than the small.

Fig. 42. - Alveolar Large Round-celled Sarcoma from the Periosteum. X 250 (Dürck).

1, Heavy septum of connective tissue; 2, delicate connective-tissue reticulum; 3, polyhedral cells with vesicular nuclei.