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

Abstract

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.

Figure 1

Keratoacanthoma on the left lower lip.

Figure 2

Locally arising squamoproliferative lesion composed of lobules of keratinocytes with glassy cytoplasm and mild cytological atypia, extending to the upper dermis consistent with keratoacanthoma. In the background there are scattered vacuoles, a dense histiocytic infiltrate and filler deposition, in keeping with hyaluronic acid. Haematoxylin and eosin; original magnification × 2

Figure 3

Amorphous basophilic material in keeping with hyaluronic acid associated with a dense histiocytic infiltrate comprising foamy histiocytes and pseudolipoblasts, features consistent with a reaction to cutaneous filler. Haematoxylin and eosin, original magnification x 10 (top) and × 20 (bottom).