18F-FDG PET/CT imaging for a gastrointestinal mantle cell lymphoma with multiple lymphomatous polyposis

Figure 3 Pathological findings. A: Macroscopic specimen showed perforation in the duodenal bulb; B: Histopathologically, lymphoma lesion in the duodenal bulb invaded deep into the muscularis propria (HE stain, x 20); C: Tumor cells varying in size from small to middle-sized densely proliferated (HE stain, x 200); D-F: These tumor cells were positive on immunohistochemical staining for CD20 (D), CD5 (E), and Cyclin D1 (F), findings compatible with mantle cell lymphoma (x 200); G: Ki-67 proliferative (MIB-1) index in the duodenal bulb was 50.2% (1397 cells/2781 cells) (x 200).