An elderly male presented with history of intractable diarrhea. His bone marrow and renal biopsy as shown below. Which of the following is the most appropriate diagnosis?

Ans. (b) Multiple myeloma(Ref: R 9/ 595)Key to the image: 1 - Increase in plasma cells in marrow, 2 - Kidney biopsy with pink deposits in glomerulus, 3 - Fibrils in electron microscope. So the diagnosis is Multiple myeloma, probably AL amyloidosis of kidney