Reflectance confocal microscopy for the in vivo detection of Treponema pallidum in skin lesions of secondary syphilis

Abstract

Background: Secondary syphilis is a diagnostic challenge that relies on microscopic and laboratory tests.

Objective: We sought to assess the usefulness of in vivo reflectance confocal microscopy (RCM) to detect Treponema pallidum in lesions suggestive of secondary syphilis.

Methods: Macular and papular skin lesions from 3 patients clinically suggestive of secondary syphilis were imaged by RCM and confirmed by skin punch biopsy.

Results: In all lesions RCM demonstrated elongated small bright particles with a spiral shape intermingled with the keratinocytes. These features corresponded with immunohistochemical findings that revealed several spirochetes infiltrating the epidermis.

Limitations: Unlike immunohistochemistry, RCM did not visualize T pallidum in the dermis and vascular walls because of limited imaging depth. The specificity and sensitivity of this technique need to be assessed.

Conclusion: RCM may be an effective diagnostic tool for in vivo real-time imaging of T pallidum in skin lesions of secondary syphilis, and seems to correlate well with immunohistochemistry.