Evaluation of Rare Insulin-derived Amyloidoma With 18 F-FDG PET/CT.

Amyloidosis causes extracellular tissue deposition of insoluble polymeric protein fibrils. Insulin-derived amyloidosis (AIns) is a rare complication of insulin therapy, causing insulin accumulation at the repeated injection site, forming subcutaneous lumps. This causes impaired insulin absorption, affecting further glycemic management. Our patient had anterior abdominal soft tissue lesions and a biopsy concerning multiple myeloma. 18 F-FDG PET/CT done to evaluate any osseous/other extraosseous lesions demonstrated hypermetabolic lesions confined to the anterior abdomen. The mass was excised, and histopathology revealed insulin-derived amyloidoma. Per the literature search, only 1 previous case of AIns has been evaluated with PET/CT. PET/CT helps assess disease extent, localize, guide biopsy, and follow-up.