What is a pencil cell?

Altered red cell: These are long, slender, small red blood cells that for some reason form in the presence of true iron deficiency, less so in anemias with small red cells that have other causes. They actually look like hot-dogs and don't have pencil-points, .

Deformed red cell: Pencil cells are red blood cells that are deformed so that they are cylindrical, about 3 times as long as they are wide. They are usually seen in people who are iron deficient.