Sections demonstrate a large diverticulum lined by small intestinal mucosa. Focally, ectopic gastric mucosa is identified in the tip of the diverticulum. Beneath the mucosa, in the wall of the diverticulum, there are nodules of basophilic cells. At higher magnification, these cells are forming nests and cords. The nuclei are round and uniform with "salt and pepper" chromatin pattern. There is a moderate amount of amphophilic cytoplasm. Chromogranin stain is positive in these cells.