Lip nodules caused by hyaluronic acid filler injection: report of three cases.

Many dermal fillers have been used for reducing facial skin lines and for providing lip augmentation, and hyaluronic acid (HA) is one of the most widely used agents. One of the main commercial forms of HA is Restylane (Q Med, Sweden) produced by microbiological engineering techniques. Although HA is non-immunogenic, hypersensitivity and Granulomatous foreign body reactions have been reported. Herein, we report three female patients (average age 56 years) who presented with firm nodular lesions of the lip and a history of injection with HA (Restylane, Q Med, Sweden). Histopathologically, all cases showed pools of amorphous hematoxyphilic material surrounded by bands of densely collagenized connective tissue with no inflammation or foreign body reaction. Histochemical stains confirmed the presence of acid mucopolysaccharides such as hyaluronic acid. We conclude HA (Restylane, Q Med, Sweden) is an inert filler that may persist at an injection site, resulting in a tumor-like nodule.