Actinomycosis of the face While common in cattle (especially young weaned bulls and heifers), actinomycosis is rare in humans. It’s an opportunistic infection, becoming entrenched while the immune system is compromised by disease or malnutrition, and when it becomes established inside the body (most often the chest) is often misdiagnosed as a neoplasm (neoplasm = “new growth” - a tumor). On the face, it causes a slow-growing, lumpy surface, that ignores tissue layers, and ...