A granuloma's a medical term for a ball-like collection of immune cells which forms when the immune system attempts to wall off substances that it perceives as foreign but's unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as other materials such as keratin, suture fragments and vegetable particles. A granuloma's therefore a special type of inflammatory reaction that can occur in a wide variety of diseases, both infectious and non-infectious.… (More on Granulomas)