A case of catastrophic APS with involvement of the ampulla of Vater. (A) Morphologic appearance (on endoscopic examination) of ampulla of Vater, which is grossly edematous and unusual in appearance. (B) Ampullary biopsy showing small-vessel thrombosis. (Olympus BX41 microscope, objective lense used was the Olympus UPLANF 40×/0.75NA dry, original magnification ×400, H&E stain; camera: NIKON COOLPIX 995, image acquistion software: Olympus CAMEDIA Master.) (C) Resolution of changes after treatment with intravenous anticoagulation, corticosteroids, antibiotics, plasma exchange, and intravenous immunoglobulin.