PCR testing for Treponema pallidum in paraffin-embedded skin biopsy specimens: test design and impact on the diagnosis of syphilis

Background: Syphilis, a chronic infection caused by Treponema pallidum (T. pallidum), is a disease which is increasing in incidence, and thus more and more becoming a differential diagnosis in routine pathology. Aim: Since histological changes are not specific, we sought to develop a polymerase chain reaction (PCR)-based molecular assay for the detection of T. pallidum in formalin-fixed, paraffin-embedded tissues, and evaluate its diagnostic power, especially in comparison with other ancillary methods, i.e. immunohistochemistry and Dieterle staining. Methods: 36 skin biopsies with the clinical and /or serological diagnosis of syphilis were evaluated by morphology, immunohistochemistry and s…