Auer rod-like inclusions in multiple myeloma: Report of two diagnostically challenging cases.

Non-immunoglobulin intracytoplasmic inclusions in plasma cells of multiple myeloma are very rare presentation. These are morphologically similar to Auer rods but chemically different from them. We studied two cases of multiple myeloma in a 60-year-old woman and 45-year-old man. In both cases, plasma cells of bone marrow aspirate revealed multiple Auer rod-like inclusions (ARLI). Sudan black B (SBB) and myeloperoxidase (MPO) cytochemistry were negative. Serum protein electrophoresis in both of them showed M spike, one with raised IgA-kappa levels, while the other with raised IgG-kappa levels. Very few case reports have been published in the literature and its prognostic implications are still unknown. Due to its rarity, it is important to distinguish such cases from acute myeloid leukemia and its exact incidence with its therapeutic and prognostic implications.