A, Case 1. Electron micrograph showing abundant rhomboid crystals within the proximal tubular epithelium (uranyl acetate stain, original magnification ×3000). B, Case 2. Electron micrograph showing the latticelike structure of the rhomboid crystals (uranyl acetate stain, original magnification ×50 000).Figure 4. Case 5. Immunogold stain for λ light chain, which is positive within phagolysosomes in the proximal tubular epithelium. The stain for the κ light chain was negative (not shown) (original magnification ×12 000).