Share this article on:

Contaminant Treponema-Positive Bacteria in Cutaneous Biopsies With an Infiltrate Rich in Plasma Cells

Fernandez-Flores, Angel MD, PhD

American Journal of Dermatopathology: June 2011 - Volume 33 - Issue 4 - pp 415-417
doi: 10.1097/DAD.0b013e3181e84e4b
Letter to the Editor

The Service of Cellular Pathology, Clinica Ponferrada, Ponferrada, Spain

To the Editor:

Since we published a previous article on possible pitfalls of the immunohistochemical method for Treponema,1 we have seen some other interesting examples that we would like to report.

It is well known that when tap water is used to wash the slide (instead of distilled water), in many occasions, it is possible to observe bacteria on the slide, in the areas that surround the tissue of the biopsy. It is less known, perhaps, that distilled water can also be contaminated by bacteria. We have observed how these bacteria are immunostained many times with the antibody for Treponema. This fact would be merely anecdotal, except for the fact that on some occasions, such bacteria can be superimposed to the tissue section. Figure 1 is an example of this. It shows a cutaneous biopsy with a dermal inflammatory infiltrate rich in plasma cells. Due mainly to the presence of these cells, immunostaining for Treponema was requested and, some positive bacteria were evidenced on the epidermis. Some of them were even the same length as Treponema (between 6 and 20 μm), although they were obviously easily distinguishable from Treponema due to their morphology that was not spiralled. The diagnostic clue was readily evident from looking at the slide out of the tissue, where the same types of bacteria were found (Fig. 2).

In many cutaneous biopsies with an inflammatory infiltrate rich in plasma cells the clinical history can be nondeterminant for the diagnosis as “syphilitic lesion.” Thus, it is crucial to take into account that there can be “transient” bacilli on the epidermis of the biopsy. This, therefore, can induce to mistakes if we do not consider their nonspiral morphology.

Angel Fernandez-Flores, MD, PhD

The Service of Cellular Pathology, Clinica Ponferrada, Ponferrada, Spain

Back to Top | Article Outline


1. Fernandez-Flores A. Immunostaining for Treponema pallidum: caution in its evaluation. Am J Dermatopathol. In press.
© 2011 Lippincott Williams & Wilkins, Inc.