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.

Cutaneous Borreliosis With a T-Cell-Rich Infiltrate and Simultaneous Involvement by B-Cell Chronic Lymphocytic Leukemia With t(14;18)(q32;q21).

Pseudolymphomatous infiltrates in Borrelia infection of the skin most commonly manifest with dense B-cell infiltrates and plasma cells. Cutaneous infiltrates of B-cell chronic lymphocytic leukemia (B-CLL) may accumulate at sites of infection, including Borrelia infection. We report an unusual constellation in a patient with synchronously diagnosed B-CLL and Borrelia infection of skin presenting with a dense dermal T-cell-rich infiltrate masking specific leukemic infiltrates of neoplastic B cells in the context of B-CLL harboring t(14;18)(q32;q21). Specific cutaneous involvement by B-CLL was confirmed by the detection of t(14;18)(q32;q21) (BCL2-IGH) using FISH in neoplastic B cells within the skin infiltrates. Borrelia burgdorferi (sensu lato) DNA detected by nested polymerase chain reaction in the skin biopsy and serological findings proved Borrelia infection. Complete resolution of the cutaneous infiltrates was observed after antibiotic treatment. This case demonstrates that Borrelia infection of the skin may present with dense T-cell-rich infiltrates mimicking cutaneous T-cell lymphoma and masking the synchronous presence of neoplastic B cells in the context of B-CLL.