PLE-5528

A 56-year-old male presented with recent onset of bipedal edema. His blood pressure was 120/80 and heart rate was 90. He does not recall any history of recent infections but has been reported to have multiple sexual partners. Over the past few weeks, he noticed his urine to be foamy and bubbly, and would have puffy eyelids especially upon waking in the morning. Further examination revealed +3 urine protein, 0-2 RBCs, 0-1 WBCs, +1 pus cells, no casts or crystals, urine specific gravity of 1.015, and urine pH of 5.5. A renal biopsy was eventually performed, which revealed large hypercellular glomeruli, thickened glomerular basement membrane, and increased mesangial matrix. Immunofluorescence showed a granular pattern of C3, IgG, and C1q, while electron microscopy revealed subendothelial deposits. What is the most likely finding?