Histopathologic patterns of erythema migrans and borrelial lymphocytoma

Abstract

Erythema migrans and borrelial lymphocytoma are early signs of Lyme borreliosis. After infection with Borrelia burgdorferi via a tick bite, the body undergoes a series of events in an attempt to destroy the microorganism or limit its spread to other sites. Biopsies taken from patients soon after a tick bite show the tick head and neighboring skin with edema, vascular dilation, extravasation of erythrocytes, and an inflammatory infiltrate of neutrophils and eosinophils. If the spirochetes persist in the skin, the infiltrate shows predominantly lymphocytes and, in many circumstances, plasma cells. The infiltrates in the early phase of the disease are histologically characterized by the presence of both B and T lymphocytes (helper and suppressor phenotypes), macrophages, interdigitating reticulum cells, mast cells, and plasma cells. After dissemination, B. burgdorferi appears to cause direct organ damage or to provoke immune mechanisms resulting in inflammation. 1