Glomerular Diseases USMLE Step 1 Practice Question

A 56-year-old man with a 10-year history of hypertension and chronic kidney disease stage 3 presents to the emergency department with acute dyspnea, hemoptysis, and cough productive of blood-tinged sputum. His wife reports he has had fatigue and malaise for 2 weeks. Vital signs: BP 162/94 mmHg, HR 102/min, RR 24/min, SpO2 92% on room air. Physical examination reveals crackles in bilateral lower lung fields. Laboratory studies show: serum creatinine 2.3 mg/dL (baseline 1.8 mg/dL), BUN 48 mg/dL, urinalysis with 3+ protein and dysmorphic RBCs, 24-hour urine protein 3.5 g/day. Serum complement C3 and C4 levels are normal. Serum ANCA (c-ANCA, p-ANCA), ANA, and anti-GBM antibodies are all negative. Chest X-ray shows bilateral alveolar infiltrates without pleural effusion. Kidney biopsy demonstrates membranoproliferative glomerulonephritis with electron-dense intramembranous deposits on electron microscopy arranged in a characteristic 'ribbon-like' or 'dense intramembraneous deposit' pattern. Which of the following is the most likely diagnosis?