Lymphosarcoma.
—This tumor is composed of cells similar to the previous form, but enclosed in a delicate meshwork resembling that of lymph nodes, hence the term lymphosarcoma. Lymphosarcomas are not to be confounded with enlargements nor with the specific granulomas involving these lymphatic structures.
B. Spindle-cell Sarcoma.
—In this form the cells have a spindle shape and run in all directions, so that sections will show them in various shapes and sizes. In some cases the cells are small and slender, in others large. The size of the cell is a measure of the malignancy of the tumor. (See [Plate XVII].)
The largest of these spindle cells are frequently striated transversely like voluntary muscle fiber, and tumors composed of this form have been considered as tumors of striped muscle tissue, and are generally called rhabdomyoma. There is no tumor of striped muscle fiber, and the rhabdomyomas of writers generally should be considered as spindle-cell sarcoma, or may be dignified by the name myosarcoma. (See [Rhabdomyoma], under [Myoma].)
Alveolar Sarcoma.
—This is a rare form, in which the cells, contrary to the general rule of sarcomas, assume an alveolar arrangement strongly imitating that of epithelial cells in carcinoma. Almost invariably, however, on close examination it will be possible to distinguish a delicate reticulum between individual cells, which is never met with in cancer.
C. Myeloid, or Giant-cell Sarcoma.
—In this form the tissue resembles histologically the red marrow of young and growing bone, containing large numbers of multinuclear cells embedded in a matrix of spindle or round cells. These tumors usually occur in the long bones, and when freshly cut look like a piece of liver. They constitute most of the epulides or cases of epulis—i. e., spongy tumors springing from the gums. (See [Plate XVIII., Fig. 2].)
Fig. 79