Can the cause of a foreign body reaction be diagnosed histologically?

Sometimes. Often, a tattoo granuloma may retain some color or pigment that can help with the diagnosis. Silicone, paraffin, and other oils are often accompanied by fibrosis and a characteristic “Swiss cheese” appearance. The Swiss cheese–like holes are actually cavities formerly filled with the oily material that is lost during tissue processing. Also, some foreign bodies are birefringent under polarized light (e.g., talc, starch, silica, and some types of sutures).

Parada MB, Michalany NS, Hassun KM, et al: A histologic study of adverse effects of different cosmetic skin fillers, Skinmed 4:345–346, 2005.