Join Date: Sep 2011
Location: Mechanicsburg, PA, USA
I have had several experiences with both injection sarcomas and with sterile abcesses. Sarcomas come about when an outside inrritant (like an injected drug) irritates the tissues of a muscle and the body tries to contain the irritation by surrounding it with a bunch of fast growing cells. This does create a lump, usually a solid lump, that is soft to the touch and most likely will never get cancerous or grow much larger than it already is. Often, the sarcomas will slowly disappear over the years and the body notices the irritation caused by the drug has gone away and the body removes the sarcoma through a natural process called 'remodeling'; returning the area of the sarcoma back to its original flat form. This process can talke ten years or more and most people do nothing about these soft, non-cancerous growths as long as they do stay soft and small; if they get hard or start to grow larger, they then have to be removed and biopsied to eliminate a precancerous condition.
Steril abcesses are usually fluid filled, but can accompany a small sarcoma. Again, an irritation has happened from the injection of a drug or whatever and the body is trying to resolve the irritation. The abcess remains sterile because the procedure that delivered the drug (injection with a needle) was done with aseptic technique and no disease causing bacteria were injected under skin, just the drug that caused the reaction. The body floods the site with blood serum, causing the fluid filled blister, with the idea of diluting the irritant drug and ending the irritation. It is usually the treatment to remove the excess fluid with a needle, but if this cannot be done and there is also a sarcoma present, the sterile abcesses are usually left to resolve themselves. The skin is in tact, there is no sepsis or disease organisms present, and eventually the body will reabsorb the fluid and the lump will go away. Usually this takes anywhere from a few weeks to months when the lump is just fluid filled; much longer is a sarcoma is also present.
That is it. The reason they happen, how they are treated and what may happen in the future. Mine, I just watched. The sterile abcesses went away within a month or so, as did one of the sarcomas; but the other sarcoma remained for the entire life of the cat and never disappeared or changed precancerous.