Erythema migrans: a reassessment of diagnostic criteria for early cutaneous manifestations of borreliosis with particular emphasis on clonality investigations

Abstract

Infiltrates in erythema migrans are dominated by T cells followed by CD68+ histiocytes and B lymphocytes. Plasma cells are an inconsistent finding. Pseudoclonality of IgH rearrangement is a result of infiltrates being sparse in B lymphocytes and represents a pitfall in molecular pathological diagnosis that can only be avoided by duplicate or triplicate tests. Incidental B-cell clonality may be encountered in patients with unequivocal erythema migrans and should not be interpreted as a malignant lymphomatous process induced by borrelia.