This case study presents a patient with multiple myeloma whose serum specimen exhibits two distinct bands in serum protein electrophoresis but only one band in immunofixation electrophoresis. This latter, single band corresponds to the M-spike. An investigation is presented to determine the identity of this disappearing or phantom band. Furthermore, this case is used as a teaching point to explain the criteria used for staging multiple myeloma, how a cell can become a myeloma propagating cell, methods that can be used to identify unexpected bands in serum protein electrophoresis, possible explanations for bands in the beta region, the usual treatment regimens in multiple myeloma and finally specimen collecting and handling procedures for serum protein electrophoresis. Read more.