Detection of spirochetal micro-organisms by focus-floating microscopy in necrobiotic xanthogranuloma

BackgroundNecrobiotic xanthogranuloma (NXG) is a rare histiocytic disorder of unknown origin.ObjectiveWe conducted an investigation of skin biopsy specimens from 7 patients with NXG for the presence of Borrelia by focus-floating microscopy.MethodsFocus-floating microscopy is a recently described, modified immunhistochemical technique in which the sections of a slide are simultaneously scanned both horizontally and vertically. Focus-floating microscopy is more sensitive for the detection of micro-organisms than polymerase chain reaction.ResultsBorrelia could be detected as single, paired, or clusters of spirochetes in 6 cases of NXG whereas two cases investigated with a Borrelia-specific polymerase chain reaction (23s-RNA) remained negative.LimitationsLimited biopsy material in each patient prohibited a more detailed study of the life history of cutaneous lesions in NXG.ConclusionsThe detection of this micro-organism in NXG points to a specific involvement of B burgdorferi or other similar strains in the development of or as a trigger of this disease.