Fibrin in human tumors.

Sections of human tumors have been stained for fibrin deposits by the fluorescein label technic. Large clots of extravascular fibrin were demonstrated in most of the tumors tested. No such large clots were found in the several normal tissues investi gated. However, there was some staining of certain areas of connective tissue in both normal and tumor tissues. The fibrin deposition observed in the spontaneous human tumors was very similar to that of the several transplanted rat tumors. This observa tion of the presence of fibrin does not give information about the rate of fibrin depo sition.