Background: The cutaneous manifestations of Borrelia burgdorferi infection include an early phase of erythema chronicum migrans and a late stage of acrodermatitis chronica atrophicans lesions.
Objective: We describe 11 patients with peculiar cutaneous manifestations and distinctive histopathologic findings as the result of B burgdorferi infection.
Methods: Eleven patients with B burgdorferi detected by polymerase chain reaction or polymerase chain reaction enzyme-linked immunosorbent assay in their cutaneous lesions were included in this study. We analyzed clinical data and histopathologic findings in all patients. The inflammatory infiltrate was also immunohistochemically investigated.
Results: Most patients showed a peculiar clinical setting of morphea, and a few cases presented the characteristic appearance of erythema chronicum migrans instead of acrodermatitis chronica atrophicans, as would be expected in a late phase of B burgdorferi infection. The histopathologic findings were similar in all cases and consisted of an interstitial inflammatory infiltrate mostly composed of histiocytes dispersed among the collagen bundles of the dermis and focal areas of small pseudorosette formation, characterized by small histiocytes radially disposed around thick collagen bundles. In some cases there were also a few plasma cells intermingled with the histiocytes.
Conclusion: Cutaneous lesions with clinical appearance similar to that of morphea and histopathologic features closely resembling those of the interstitial type of granuloma annular may be seen in intermediate-stage cutaneous lesions of B burgdorferi infection. These clinical and histopathologic findings represent a constellation of findings that have not been previously characterized as a cutaneous manifestation of B burgdorferi infection.