Cutaneous manifestations of Lyme borreliosis. Clinical definitions and differential diagnoses.

At the IVth international Conference on Lyme borreliosis the cutaneous manifestations and differential diagnoses were reviewed. Erythema migrans (EM) is a spontaneously healing erythematous lesion occuring at the site of borrelial inoculation. Typically it is homogeneous or is annular with centrifugal spreading. Atypical variants may also occur. Borrelial lymphocytoma (BL) generally presents as a bluish-red nodule. Histologically there is a dense polyclonal lymphocytic infiltrate. Predilection sites are the ear and the breast. It may appear secondarily to EM or be the first manifestation of Lyme borreliosis. EM and BL are early, localized cutaneous manifestations, but sometimes extracutaneous signs or symptoms of disseminated disease may appear simultaneously with either of these lesions. Multiple EM-like lesions, occurring as a result of hematogenous spread, are the cutaneous markers of disseminated disease. Acrodermatitis chronica atrophicans is a chronic skin lesion which is generally seen on the extremities. It starts with an inflammatory phase with bluish-red discoloration, which years to decades later may be followed by an atrophic phase. Sclerotic skin lesions may also develop. Important differential diagnoses are granuloma annulare, malignant lymphoma, benign lymphoreticular infiltrations and sclerotic lesions of non-borrelial origin, collagenoses and circulatory insufficiency.