 In blister cells, an outer rim of cytoplasm is maintained, and when this ruptures, the resulting bite cells have horn-like projections.Blister cells appear as red blood cells containing a peripherally located vacuole.Bite cells are caused by G6PD deficiency, NADPH deficiency, thalassemia, glutathione synthase deficiency, and other red-cell enzymopathies involving the pentose phosphate shunt, oxidative drugs and unstable hemoglobins.