ACRODERMATITIS CHRONICA-ATROPHICANS - A CHRONIC T-CELL-MEDIATED IMMUNE-REACTION AGAINST BORRELIA-BURGDORFERI - CLINICAL, HISTOLOGIC, AND IMMUNOHISTOCHEMICAL STUDY OF 5 CASES

Background: Acrodermatitis chronica atrophicans (ACA) is a late manifestation of infection caused by Borrelia burgdorferi. Objective. Our purpose was to study the clinical, histopathologic, and immunohistochemical findings in patients with ACA to understand better the pathogenesis of the disease. Methods. Five patients were studied. Skin biopsy specimens were obtained from active lesions for histologic and immunohistochemical studies. Results: Clinical lesions included an initial erythematous discoloration in one patient and violaceous infiltrated plaques and nodules in four patients, three of whom also had late atrophic lesions. Biopsy specimens showed a dermal perivascular and interstitial lymphocytic infiltrate with plasma cells. There was a predominance of CD3+, CD4+ T cells in the dermal infiltrate. B cells were present in three patients. The dermal infiltrate showed an intense expression of lymphocyte function-associated antigen. The intercellular adhesion molecule type 1 was expressed on endothelial cells, perivascular mononuclear cells, and focally on basal keratinocytes. Conclusion: Our findings suggest that a chronic, T-cell-mediated immune reaction against B. burgdorferi is involved in the pathogenesis of ACA.