Background and Aims

ANCA specific antibodies are related with small vessel vasculitis (SVV). Nevertheless, atypical ANCA (xANCA) are frequent in clinical practice and its positivity raises doubts and consultation in order to rule out a systemic autoimmune disease. The aim of this study is to assess whether xANCA are related with autoimmune diseases.

Methods

We collected all patients with xANCA result during 2015-2021 in a county hospital (Hospital General de Granollers) and its diagnostic.

Results

78 patients were identified, with a mean age of 62+/-8 yo, 63% of them being women and 14% smokers. None of them reported cocaine use.

14 patients (18%) were diagnosed with interstitial lung disease being interstitial usual pneumonitis (IUP)/ pulmonary fibrosis the most frequent (10 patients).

11 patients (14%) were diagnosed with inflammatory bowel disease (10 ulcerative colitis and 1 Chron’s disease), 3 autoimmune hepatitis and 2 primary biliary cholangitis.

10 patients (13%) had a bacterial infection requiring hospitalization and intravenous antibiotics (being the most frequent respiratory tract infections and urinary tract infections). One patient had an acute Epstein-Barr infection, three patients had latent tuberculosis and one patient cured syphilis.

Only one patient was diagnosed with autoimmune systemic disease: a sarcoidosis. 5 patients had been previously diagnosed with seropositive rheumatoid arthritis and three of CTD (two antiphospholipid syndrome and one undifferentiated CTD).

Conclusions

No patient was diagnosed with SVV. Multitude of diseases with autoimmune or inflammatory background and bacterial infections are related with xANCA. ANCA should be restricted when suspecting a SVV and an unspecific result (xANCA) should be careful assessed.