25734 Migratory panniculitis of the pannus

Abstract

We present a case of a 63-year-old Hispanic female with a medical history significant for type II diabetes mellitus who presented with a 1-year history of painful migratory nodules on her abdomen. She reported that approximately 2 months after beginning weekly injections with exenatide for diabetes she noticed a tender lesion on the left lower quadrant of her abdomen. Her primary care physician diagnosed it as a lipoma. Over the subsequent months she developed a new painful nodule roughly every week on her abdomen that coincided with prior exenatide injection sites. She stated that the lesions were initially painful then spontaneously resolved after several weeks. On examination there were two 1-cm deep-seated nodules that were tender to palpation without any overlying epidermal changes. An ultrasound demonstrated two 3-6 mm foci of increased echogenicity in the subcutaneous fat. One 4-mm punch biopsy of each of the 2 lesions demonstrated a predominantly septal panniculitis containing amorphous material associated with a mixed inflammatory infiltrate. No organisms were identified with GMS and AFB stains; however, the AFB stain highlighted the amorphous material. Infrared spectroscopy of the material closely matched normal tissue containing poly(lactide-co-glycolide) (PLGA). Exenatide extended-release is incorporated in PLGA microspheres. Given the clinical presentation, histologic findings, and infrared spectroscopy results, a diagnosis of exenatide-induced panniculitis was made. Clinicians should be aware of possible injection site reactions with subcutaneously administered medications.