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Unexpected non-reactive nontreponemal serology in secondary syphilis: The prozone phenomenon and clinician-laboratory
Mahomed A Aboo1, Matilda Mphahlele2, Melanie Louw3,4
1Department of Internal Medicine, Tambo Memorial Hospital, Johannesburg, South Africa.
Abstract:
We describe a case of a 22-year-old woman living with human immunodeficiency virus (HIV) who presented with classical features of secondary syphilis. Initial Rapid Plasma Reagin (RPR) testing was unexpectedly non-reactive; however, repeat RPR testing with serum dilution yielded a reactive result, illustrating the prozone phenomenon.
Contribution:
The prozone phenomenon is uncommon. We aim to encourage clinician-laboratory communication when there is a high pretest probability of syphilis, with serological discordance, to facilitate prompt diagnosis and treatment.
