Background: Morphoea or localized scleroderma is a cutaneous inflammatory disease with still unknown aetiology. Borrelia burgdorferi as causative agent has been discussed controversially.
Objectives: To assess the evidence for infection with B. burgdorferi in patients with morphoea by focus-floating microscopy (FFM).
Methods: Using standard histological equipment, tissue sections stained with a polyclonal B. burgdorferi antibody were simultaneously scanned through in two planes: horizontally as in routine cytology, and vertically by focusing through the thickness of the section, i.e. FFM. Part of the material was also investigated with a Borrelia-specific polymerase chain reaction (PCR).
Results: One hundred and twenty-two cases of morphoea and 68 controls (58 negative and 10 positive by PCR) were investigated for the presence of Borrelia within tissue specimens. Using FFM Borrelia was detected in 84 cases (68.9%) of morphoea and in all positive controls, but was absent in all negative controls. Borrelia was significantly more frequent in early inflammatory-rich (75%) than late inflammatory-poor (53%) cases (P = 0.018). What seemed to be vital microorganisms were mostly found close to the active border, while degenerated forms were more common in fibrosclerotic parts. The presence of B lymphocytes determined by CD20 staining proved to be a good positive predictor of the microorganism (correlation 0.85, P < 0.001). Borrelia-specific DNA was detected in only one of 30 cases of morphoea analysed by PCR.
Conclusions: FFM is a reliable and highly sensitive method to detect Borrelia in tissue sections. The frequent detection of this microorganism in morphoea points to a specific involvement of B. burgdorferi or other similar strains in the development of or as a trigger of this disease.