Lipiduria or lipuria is the presence of lipids in the urine.
Lipiduria is most frequently observed in nephrotic syndrome where it is passed as lipoproteins along with other proteins.
[3] When lipiduria occurs, epithelial cells or macrophages contain endogenous fats.
Oval fat bodies exhibit a "Maltese cross" configuration under polarized light microscopy.
[4] The Maltese cross appearance occurs because of its liquid-crystalline structure giving it a double refraction (birefringence).