Acellular urinary casts Fatty casts 2017-06-27T11:10:06Z The presence of fatty casts in urine may be associated with heavy proteinuria in patients with nephrotic syndrome. A type of acellular urinary casts that contain lipid droplets, oval fat bodies or cholesterol crystals, and are often associated with the free forms of these elements. Their identification may require the use of polarized light microscopy, under which fatty particles embedded into the cast matrix appear as Maltese crosses.