073. RHEUMATOID VASCULITIS AND POLYARTERITIS NODOSA: THE ROLE OF ANTI-CYCLIC CITRULLINATED PEPTIDE ANTIBODIES

Abstract

Background: Classical classification of vasculitis is often not fully conclusive making, for example, rheumatoid vasculitis (RV) and polyarteritis nodosa (PAN) barely indistinguishable. Clinical setting and biomarkers such as anti-cyclic citrullinated peptide (anti-CCP) antibodies are of help to assure diagnosis. Methods: A case of a systemic vasculitis in a healthy male is reported setting the differential Sk diagnosis of RV and PAN. Results: We present the case of a healthy 63 years-old gentleman, with livedo reticularis in lower extremities, painless nodules and unilateral hypoesthesia of medial malleoli. Painless purple erythematous macular lesions on right hand and feet, nailfold lesions and digital necrosis was found. No arthritis, fever nor constitutional symptoms were present. Initial study found elevated inflammatory markers (C-reactive protein of 89 mg/L) with absence of anemia and leukocytosis, negative blood cultures and viral serologies, no cryoglobulins and no proteinuria nor alterations in sediment. Negative autoimmunity biomarkers were found (including rheumatoid factor, complement, antinuclear autoantibodies and ANCA) except for the presence of anti-CCP at high titers (>250 kU/L). Skin biopsy demonstrated medium sized vasculitis with arterial wall inflammation that destructed vessel's wall and caused obstruction. Chest and abdominal CT scan was clear. Electroneuromyography showed mononeuritis multiplex and distal asymmetric sensory neuropathy. Finally, hand and renal angiography evidenced circulation obstruction of necrotic finger with no aneurisms. Discusion There are no pathognomonic findings defining RV nor PAN - not even histopathological findings are definitive - making clinical setting crucial to differentiate both entities. In the presented case, the absence of prior RA and the compatible clinic makes PAN the most likely diagnosis. RV occurs more frequently in patients with long-standing RA but the presence of anti-CCP at high titers has been pointed to have a high specificity for rheumatoid vasculitis in a cohort of patients with systemic vasculitis and it has proven to predict which patients with any type of arthritis will develop RA. Conclusion: RV and PAN could be two clinical entities difficult to distinguish, being RV a rare disease. Anti-CCP antibodies could be helpful in the diagnosis but in cases without joint involvement long term follow-up may contribute to setting the diagnosis.