Linear scleroderma 'en coup de sabre' associated with facial atrophy in a patient seropositive for Borrelia burgdorferi: a true case of molecular mimicry?

Borrelia burgdorferi has been linked to the pathogenesis of localized scleroderma (LSc) and lichen sclerosus et atrophicus. However, considerable controversy still exists as to the actual role. We describe a peculiar presentation of linear scleroderma en coup de sabre associated with facial atrophy in a patient seropositive for B. burgdorferi, raising the possibility that this spirochete might trigger the clinical appearance of this disease. Infectious agents may act as triggers of autoimmune skin diseases via direct damage or molecular mimicry, because of homologies between microbiologic proteins and skin. Increasing clinical and experimental evidences suggest, in fact, the possible association of infectious agents with autoimmune diseases, and cross-reactivity between host self-antigens and microbial determinants was also observed. Infecting pathogens express peptides that are similar in structure or sequence to particular selfcomponents, and this may induce autoimmune responses.