Wegener's granulomatosis: false positive anti-neutrophil cytoplasmic antibody test

The anti-neutrophil cytoplasmic antibody (A.N.C.A.) test is a solid phase radioimmunoassay which detects auto-antibodies specific for Wegener's granulomatosis. The case of a young male is reported with a nasal septal perforation who was extensively investigated revealing no other clinical features, apart from a positive A.N.C.A. test, warranting a diagnosis of Wegener's granulomatosis. It is felt the case represents a false positive A.N.C.A. test and emphasises that the test, whilst useful, should be interpreted in the context of other diagnostic criteria.