Inf lammatory Mass with Fibrinoid Necrosis of Vessels Caused by Methylene Blue Marking of a Colonic Polyp

Methylene blue is a relatively non-toxic dye that is used in a variety of procedures including the marking of margins and skin flaps, identifying sinus and fistulous tracts, localizing islet cell tumors, and marking colonic polyps. It has been used intravascularly for the labeling of arteriovenous malformations or to find small bleeding sites. Few adverse effects have been reported with its use. We report an unusual case of an inflammatory mass secondary to transmural injection of methylene blue that resulted in fibrinoid necrosis of arterial media mimicking a necrotizing vasculitis.