A foreign body granuloma is a mass of cells surrounding an object in the body. Normally when something enters the body, either through injection, accident or infection, cells called macrophages attack the object and basically eat it. If the object is too big for the macrophages to destroy or they cannot otherwise dispose of it, they cluster around the object and form a granuloma.
Visible symptoms of a foreign body granuloma include a painful, tumorlike lump, reddened and infected-looking skin, or small red bumps, although they are not limited to forming just at or below skin level. It is possible for granulomas to form inside the brain or other parts of the body. Animals are also susceptible to granulomas, which can lead to inflammation and, for lab animals at least, make healing from surgery difficult.
Granulomas don’t need a large solid object in order to occur. They can form around anything, even particles of liquids like tattoo ink, especially red ink. Injected silicone is also a trigger for formation of a foreign body granuloma, as are surgical cotton, piercings and cholesterol crystals found in improperly drained, injured ears. Bacterial infections can be another basis for granuloma formation.
The treatment for a granuloma of this kind depends on its location and reason for forming. In some cases, corticosteroids are the preferred treatment, but in others, such as cholesterol granulomas in the middle ear, the lump must be removed. Granulomas can also cause adjacent skin to atrophy or become thinner. A foreign body granuloma isn’t always round and can have an asymmetrical shape that projects into tissue, making surgery difficult and undesirable in some cases.
Whether a foreign body granuloma will form or not around something is unknown, and having one does not mean a person will form them repeatedly or develop them in response to everything. Granulomas can occur at any time, as well, meaning they could form a long time after the object or substance is introduced. “Dermal fillers” like collagen used in cosmetic procedures have a tendency to produce multiple granulomas at the sites where the filler was injected at the same time, and these can actually resolve on their own. If they do not, medications such as corticosteroids are the next step in treatment.