Granular casts are composed of cellular remnants and by-products of protein degradation. Granular casts appear as irregularly shaped cylinders of coarse or fine, highly refractive particles. A granular cast containing coarse brown granules is indicated by the yellow arrow in the image on the right (400× magnification). Hyaline casts are also present in this field and are indicated by the blue arrows.
The presence of an occasional granular cast is not considered pathologic.
