Utilizing a multinational collaborative network, a study provided the first systematic description of urinary vacuolar casts in patients with acute or chronic kidney disease. Notably, these casts are not included in most textbooks of urinalysis and/or urine microscopy. The investigators reported that these distinct type of casts are associated with the presence of a glomerular disease and overt proteinuria. Moreover, individuals in which vacuolar casts were identified via urinary sediment microscopy had greater degree of proteinuria and greater percentage of glomerular obsolescence than a control group of patients without vacuolar casts. Further studies will be needed to examine the prognostic value of vacuolar casts.