Serum protein electrophoresis pattern associated with elevated polyclonal IgG4 concentrations: a monoclonal-mimicking profile with potentially significant clinical implications

The SPEP pattern associated with elevated polyclonal IgG4 concentrations is significant not only as an MC mimicker to be recognised in the diagnostic workup of plasma cell dyscrasias, but also because, when confirmed by IgG4 measurement, it provides physicians with clinically relevant information, particularly within the context of IgG4-related conditions, potentially preventing unnecessary procedures that could harm the patient and delay diagnosis.