Eosinophilic Panniculitis Following the Subcutaneous Injection of Exenatide Extended-Release

Exenatide extended-release was recently developed as an antidiabetic drug; it acts as a glucagon-like peptide-1 receptor agonist. A 54-year-old male visited our clinic complaining of a subcutaneous tender nodule on his left thigh that had developed over the course of 1 week. The patient had received exenatide extended-release injections for 5 months to treat diabetes. A histopathologic examination showed septal and lobular panniculitis with lymphohistiocyte and eosinophil infiltration. The patient was diagnosed with eosinophilic panniculitis (EP) due to exenatide extended-release injection. EP is a rare type of panniculitis characterized by a prominent infiltrate of eosinophils in the subcutaneous fat layer. It is a histologic reaction pattern that is associated with various clinical conditions. Among the injection-site reactions reported in exenatide extended-release users, injection-site nodules occur infrequently. Clinicians who treat diabetics who use exenatide extended-release should be aware of the possible occurrence of injection-site nodules.