Acellular urinary casts Myoglobin casts 2019-12-22T09:23:06Z A type of acelluar casts with positive myoglobin staining A that have a surface composed of granules, which can vary in size. The granules can be rather heterogeneous, ranging from fine (finely granular cast) up to coarse (coarsely granular cast), dark, clear, and pigmented.