A Blast from the Past: Abdominal Wall Amyloidosis Due to Enfuvirtide Injections.

Enfuvirtide was the first marketed fusion inhibitor that worked by binding to glycoprotein 41 of the HIV envelope, preventing the conformational changes required for HIV fusion with CD4+ T cells. Due to its novel mechanisms of action, it was frequently used in the past as part of regimens for the indication of multi-class-resistant HIV until newer oral agents emerged. Here, we describe the case of a 40-year-old man who used enfuvirtide injections from 2012 to 2017 inclusive for multi-class-resistant HIV until he presented in 2021 with an abscess overlying a right lower quadrant mass requiring drainage via pigtail. Congo red stain of the tissue showed positive apple green birefringence on amorphous material after polarization, enabling the diagnosis of enfuvirtide-induced amyloidosis. The patient experienced significant improvement following surgical excision of the cysts and nodules. This case demonstrates that sequelae of injection site reactions can persist for many years following the cessation of enfuvirtide injections.