CONCLUSION

In this patient, the diagnosis of borrelia-associated inflammatory neuropathy in stage III borreliosis was supported by the clinical picture including joint pain, skin changes (which initially led to the misdiagnosis of dermatomyositis), positive blood and CSF serology, and finally, a characteristic inflammatory pattern in the sural nerve. In most publications on borrelia-associated neuropathy, perivasculitis is described, but bona fide vasculitis may also be present.^1–6 Thus, the biopsy findings were compatible with borrelia neuropathy.

The presence of a positive borrelia serology in a patient with a neuropathy does not necessarily prove a causal relation. In a recent study, we aimed at determining potential histological markers for borrelia-associated neuropathies on sural nerve biopsies.⁷ We found that inflammatory signs were similar in quality to idiopathic vasculitic neuropathy, but that borrelia neuropathy had distinct features including thickening of the perineurium with increased vascularization. Therefore we consider it less likely that our patient suffered from idiopathic peripheral nerve vasculitis. Given the good response to the antibiotic, we consider this interpretation even more unlikely. In most previously published cases of borrelia neuropathy, perineurial thickening is not mentioned, but in the earliest study by Meier et al. on five patients, on careful re-inspection of the published images, we conclude that these already suggest perineurial thickening as a typical feature of borrelia neuropathy.⁴ It has to be considered that most reports on borrelia neuropathy relate to stage II neuroborreliosis with the typical clinical picture of meningoradiculoneuritis, where inflammation may be much more prominent in the meninges and spinal roots than in peripheral nerve.⁸

The case shows that borrelia neuropathy may have a distinctive pathology including vasculitis. Signs of acrodermatitis atrophicans are not frequently associated. The feature of perineurial thickening may aid in the diagnosis. For the patient, an established diagnosis of borrelia-associated inflammatory neuropathy leads us to consider treatment with antibiotics rather than using only glucocorticosteroids or other immunosuppressive drugs as it is the standard treatment in idiopathic vasculitic neuropathy.^9,10 With early diagnosis and treatment of borreliosis in stages I or II, the later stages have become a rare event but this may be different in regions where borreliosis is not endemic and therefore routine serology is not done.