• Composition: These casts are composed primarily of free light chains (Bence Jones proteins) produced by the malignant plasma cells in multiple myeloma.
• Appearance: Under the microscope, myeloma casts can appear as fractured, waxy, or crystalline structures. They often have a distinctive, large, and irregular appearance compared to other types of casts.
• Clinical Significance: The presence of myeloma casts in the urine is highly suggestive of cast nephropathy and indicates significant renal involvement in multiple myeloma.