[Case of minocycline-induced vasculitic neuropathy]

A 70-year-old woman was admitted to our hospital because of fever, numbness in her extremities and right drop foot. Because her hip prosthesis had loosened as a result of infection, she had been taking 100 mg of minocycline orally for eight months. Three months before admission, she had had melena several times and body weight loss and pyrexia developed. A month before admission, asymmetrical paresthesia and numbness appeared in her extremities and finally right drop foot developed. Laboratory tests showed elevated C-reactive protein and positive anti-nuclear antibody. Abnormalities found in nerve conduction study were compatible with mononeuritis multiplex. Sural nerve biopsy revealed an occluded medium-size artery in the epineurium and axonal degeneration in the nerve fascicles, confirming the diagnosis of vasculitic neuropathy. These manifestations met the American Congress Rheumatology criteria for polyarteritis nodosa. However, her clinical conditions markedly improved after discontinuing minocycline and therefore she was diagnosed as having minocycline-induced vasculitic neuropathy. Although minocycline-induced vasculitis is a well known adverse effect of the drug, peripheral neuropathy with biopsy findings has rarely been reported. Drug induced-vasculitis is important as a differential diagnosis for mononeuritis multiplex because the symptoms can be improved by the discontinuation of an offending drug.