Facial cosmetic procedures are increasingly requested, and dermal filler materials have been widely used as a nonsurgical option since the 1980s. However, injectable fillers have been implicated in local adverse reactions. Therefore, the aim of this article was to describe the use of fine needle aspiration cytology (FNAC) in the diagnosis of foreign-body reactions to the perioral injection of dermal fillers. A 69-year-old woman presented with a painful nodule on her right nasolabial fold. Intraoral FNAC was performed, and cytologic smears were examined under optical and polarized light microscopy, showing birefringent microspheres, confirming the diagnosis of an adverse reaction caused by polymethyl methacrylate filler. FNAC is a less invasive method to confirm the diagnosis of adverse reactions caused by perioral cosmeticdermal fillers Ver menos