Epithelial cell casts appear as clear cylinders containing renal epithelial cells. These casts indicate tubular damage. In the broader cast, epithelial cells appear at random: in the narrow cast, however, epithelial cells often appear in two rows. Renal epithelial cell casts may be difficult to distinguish from WBC casts especially if the casts have begun to degrade. Contrast microscopy or supravital stains may aid differentiation.