BACKGROUNDThe false positive in conventional syphilis serological test was found in patients with multiple myeloma (MM).

OBJECTIVETo investigate the relationship between the M-protein of patients with MM and the false positive in conventional syphilis serologic test.

METHODSThe M-protein of 68 MM cases was typed with immunofixation electrophoresis and 68 cases of MM were screened with non-specific and specific syphilis serologic tests, then the samples with syphilic serological positive were chosen and confirmed with immonobloting test, finally the relationship between M protein of MM and the false positive of syphilis serological test were analysed.

RESULTSFour out of 68 cases showed the positive in syphilis serological test and further were confimed to be false positive by immunoblotting test, the false positive rate was nearly 6%. The M-protein of MM patients in our hospital mostly possessed IgG, κ type, followed by IgA, κ type, light chain κ type. In general, κ : λ = 2.4 : 1. Among samples of 4 cases with syphilis serological positive 2 cases were of IgG and κ type, 1 case was of IgG, λ type, another 1 case was IgA, κ type.

CONCLUSIONThe M-protein of IgG and IgA types in MM patients results in syphilis serological false positive reaction. The clinicians and laboratorial technicians should pay a great attention to screen the MM patients for the false positive syphilis serological test so as to avoid the misdiagnosis and subsequent embarassment.