Carbol fuchsin stain enhances detection of poly‐(d, l‐lactide‐co‐glycolide) microspheres in exenatide extended‐release cutaneous injection‐site foreign body reaction

Injection of high‐viscosity fluids into subcutaneous tissues may lead to a granulomatous reaction called sclerosing lipogranuloma (SL). Poly‐(d,l‐lactide‐co‐glycolide) (PLG or PLGA) microspheres are used as vehicles for extended‐release drugs. Here we describe the histopathologic features of a case of SL induced by exenatide extended‐release injections, and the staining pattern of PLG microspheres and microsphere remnants with carbol fuchsin.