Cutaneous borreliosis associated with T cell-predominant infiltrates: a diagnostic challenge.

BACKGROUND

With the exception of erythema migrans, Borrelia infection of the skin manifests much more commonly with B cell-rich infiltrates. T cell-rich lesions have rarely been described.

OBJECTIVE

We report a series of 6 patients with cutaneous borreliosis presenting with T cell-predominant skin infiltrates.

METHODS

We studied the clinicopathologic and molecular features of 6 patients with T cell-rich skin infiltrates.

RESULTS

Half of the patients had erythematous patchy, partly annular lesions, and the other patients had features of acrodermatitis chronica atrophicans. Histopathology revealed a dense, band-like or diffuse dermal infiltrate. Apart from small, well differentiated lymphocytes, there were medium-sized lymphocytes with slight nuclear atypia and focal epidermotropism. An interstitial histiocytic component was found in 4 cases, including histiocytic pseudorosettes. Fibrosis was present in all cases but varied in severity and distribution. In 5 patients, borrelia DNA was detected in lesional tissue using polymerase chain reaction studies. No monoclonal rearrangement of T-cell receptor gamma genes was found.

LIMITATIONS

This retrospective study was limited by the small number of patients.

CONCLUSION

In addition to unusual clinical presentation, cutaneous borreliosis can histopathologically manifest with a T cell-rich infiltrate mimicking cutaneous T-cell lymphoma. Awareness of this clinicopathologic constellation is important to prevent underrecognition of this rare and unusual presentation representing a Borrelia-associated T-cell pseudolymphoma.