The development of a keratoacanthoma following injection of hyaluronic acid-based dermal fillers into the lips.

This case report illustrates an unusual case of a keratoacanthoma (KA) developing on the lips following repeated injections with hyaluronic acid-based dermal fillers. Hyaluronic acid dermal fillers dominate nonsurgical aesthetic treatments in the UK due to their effectiveness, while also being relatively safe. The vast increase in various filler products has resulted in an increase in adverse events, although these likely remain under-reported. There have been no previously reported cases of KA directly post-hyaluronic acid injections, and KAs are not currently considered a side-effect. The patient in our case had several risk factors for developing a KA, including high sun exposure and smoking, as well as a history of repeated injections performed by a lay practitioner. Moreover, poor injection technique and repeated trauma to the lips from the injections are also likely to be implicated. Given the all-time high increase in demand for cosmetic dermal fillers, we believe that KA should be considered a possible adverse reaction of dermal fillers, particularly in patients with other significant risk factors for KA development.