A 63-year-old man has noted increasing back pain for 7 months. He has had three respiratory tract infections with Streptococcus pneumoniae within the past year. On examination, he has pitting edema to his thighs. Laboratory studies show total serum protein, 9.6 g/dL; albumin, 3.5 g/dL; creatinine, 3 mg/dL; urea nitrogen, 28 mg/dL; and glucose, 79 mg/dL. Urinalysis shows proteinuria of 4 g/24 hr, but no glucosuria or hematuria. Abdominal CT scan shows enlarged kidneys without cysts or masses. A renal biopsy specimen shows deposits of amorphous pink material within glomeruli, interstitium, and arteries with H&E stain. Which of the following diseases is he most likely to have?
A) Analgesic nephropathy
B) Diabetes mellitus
C) Membranous glomerulonephritis
D) Multiple myeloma
E) Systemic lupus erythematosus