Complications caused by filler injections are generally categorised by their timing from when the initial injection took place. A complication which occurs within days post treatment will be classed as an early event, whereas a delayed reaction will be classified as an event that occurs weeks to years post injection.1
The variation between aetiology and clinical presentations can make delayed onset nodules (DONs) more challenging to address or prevent.2 A DON is described in the literature as a palpable or visible unintended mass that occurs close to or at the injection site of dermal filler. It may appear weeks or even years after the initial treatment.3 Once identified by the practitioner, a DON can then be further categorised as inflammatory or non-inflammatory. An inflammatory nodule may be characterised by pain, tenderness, swelling, heat and erythema.4
Even though DONs remain a rare complication, they are now being recognised more often. A four year retrospective study published in 2006 of 4,320 filler treatments found only a 0.6-0.8% incidence in…
