Antineutrophil cytoplasmic antibody vasculitis associated with mycobacterium avium intracellulare infection.

A variety of possible associations between infection and antineutrophil cytoplasmic antibody (ANCA) associated vasculitis have been reported. We describe a 75-year-old woman who presented with chronic nonproductive cough, migratory polyarthralgias, and microscopic hematuria. She had an elevated perinuclear ANCA and antimyeloperoxidase antibody. She had a positive PPD test and a cavitary lesion in the right upper lung lobe; biopsy of the lung lesion showed granulomatous vasculitis, but the culture grew Mycobacterium avium intracellulare (MAI). There are clinical and histiologic similarities between ANCA vasculitis and pulmonary MAI infection. Treatment of vasculitis with immunosuppressive agents could be detrimental in patients with MAI infection. Thus, when ANCA associated vasculitis is considered, mycobacterium infection should be excluded before starting immunosuppressive therapy.