Pitfalls with anti-neutrophil cytoplasmic antibodies (ANCA).

A 39-year-old Ugandan student is described presenting with general malaise, fever and a pulmonary infiltrate. Open lung biopsy showing infarction and positive ANCA lead to a diagnosis of Wegener's granulomatosis and a treatment with immunosuppressive drugs was instituted. Five weeks after admission, however, sputum cultures turned out to be positive for Mycobacterium tuberculosis. The importance of ANCAinterpretation and the possibility of false positive results is discussed. [ABSTRACT FROM AUTHOR]