Eosinophilic granulomatous reaction after intradermal injection of hyaluronic acid.

Sir, Hyaluronic acid, one of the components of the extracellular matrix of dermis and other tissues, has natural hydrating functions with an ability to bind a large volume of water. It can be modified to form an insoluble, cross-linked, high viscosity gel whose dermal injection is suitable for the correction of soft tissue defects and the improvement of facial contouring. Dermal injection is generally believed to be safe without causing any serious adverse reactions. Acute reactions, which include bruising, erythema, and oedema, disappear within a couple of days. Delayed hypersensitivity reactions are considered to be exceptional since hyaluronic acid is non-immunogenic. We recently encountered a rare case of a delayed hypersensitivity reaction that was histologically characterized by a granulomatous change in a woman after the injection of hyaluronic acid for the correction of facial wrinkling.