Abnormal pattern of the rough endoplasmic reticulum of plasma cells in multiple myeloma with multiple concentric lamellar bodies and "single sac loops".

A patient with IgG myeloma showed a highly abnormal pattern of the rough endoplasmic reticulum (RER) with multiple concentric lamellar bodies and "single sac loops". This abnormal pattern might be due to either a complete rearrangement of the architecture within the cell, and/or a pathology in the wall of the sacs of RER.