Insulin-derived nodular amyloidosis at sites of injection.

We present the case of a 52-year-old man with insulin-dependent type 2 diabetes mellitus with multiple 2 to 3 cm firm subcutaneous masses on the abdomen, where biopsy confirmed nodular amyloidosis via apple green birefringence when stained with Congo red. Insulin, along with enfuvirtide, is one of two known medications capable of causing iatrogenic nodular amyloidosis, and patients should avoid repeat insulin injections into sites of amyloidosis, as absorption of insulin may be altered in these areas. Accurate amyloid typing may obviate the need for systemic evaluation and prevent accompanying costs and morbidity.