Light micrograph section through human tissue showing a foreign body granuloma. A foreign body granuloma forms in response to the introduction of exogenous material to the skin, or in modified endogenous material that the immune system identifies as foreign. This could refer to a splinter or thorn entering the skin and tissue. The presence of the implant changes the healing response and this is called a foreign body reaction (FBR). Haematoxylin and eosin stain.