Russell body duodenitis with immunoglobulin kappa light chain restriction

Figure 1 Endoscopic findings of duodenum. A: Endoscopic image shows a cluster of lobulated polyps in duodenal bulb; B: Numerous eosinophilic inclusions (Russell bodies, arrow) in the lamina propria and gastric foveolar metaplasia of the duodenal surface epithelium. H and E, 400 ×; C: CD138 immunohistochemistry highlights numerous mature plasma cells. The Russell bodies are round to ovoid clear spaces (arrow) within the lamina propria. Immunohistochemistry, 400 ×; D: Immunoglobulin kappa light chain immunohistochemistry shows a dark-rim staining and light internal staining pattern of Russell bodies (arrow). Immunohistochemistry, 400 ×.