How does one interpret an SPEP showing potentially obscured but non-quantifiable M-spike however an IFE showing monoclonal protein?   

Not all patients with monoclonal gammopathies make a detectable paraprotein on SPEP, or, in some cases like IgA gammopathies, it may be 'hidden' in the beta-region of the SPEP, or the rare IgD and IgE gammopathies may be too low to detect on the SPEP. In addition, for the 15-20% of patients who have...

Sounds to me like the patient has a polyclonal increase in gamma fraction with the technician trying to look for an M-spike on the graph when the patient has none. I would ask for the exact words on the IFE and SPEP used to describe these findings. I usually review all SPEP graphs myself rather than...

Excellent answer from @David H. Vesole.  Only thing I will add is the SPEP has a limit of detection that is less sensitive than IFE, so there are cases where there is a low paraprotein detected by IFE but not SPEP (as in this one). If this is a follow-up test, this likely still indicates the ...