11. Characteristics of Inflammatory Arthritis in Polyarteritis Nodosa

Background: Polyarteritis nodosa is a small to medium vessel vasculitis that can be limited to cutaneous manifestations or occur as a systemic disorder. Arthralgia has widely been reported in polyarteritis nodosa, but true inflammatory arthritis is seemingly rare in the literature. When inflammatory arthritis does occur, it has been reported to have a predilection for the lower extremities and treatment options are unclear. We report on a case series of 22 patients with a co-diagnosis of cutaneous polyarteritis nodosa and inflammatory arthritis. Methods: Advanced Text Explorer software was utilized to identify chart notes that contained the phrases “cutaneous polyarteritis nodosa” and “inflammatory arthritis”. A thorough chart review was conducted on the 34 resulting patients. Twelve patients did not have a diagnosis of cutaneous polyarteritis nodosa and/or a diagnosis of inflammatory arthritis so were excluded. The charts were then reviewed for pertinent demographic information, clinical history, lab values, pathology, synovial fluid analysis, and imaging results. Results: Of the 22 patients included, 16 (72.7%) were female with an average age of 40 at diagnosis (18-78). The arthritis most often involved the ankles (91.3%), followed by feet (43%), hands and wrists (35% each), and sacroiliitis/low back (13%). Six of the patients (27%) had erosive disease. In 77.7% of the patients cutaneous PAN preceded the inflammatory arthritis or co-occurred. Average time between diagnoses was 4.25 years. C-reactive protein was elevated in 10 (45%) and ESR in 5 (23%). ANA was positive in 23% and ANCA in 14%. Treatments varied widely with success reported most often using methotrexate (positive response in 7 of 10 patients treated). The average number of treatments utilized at the time of last follow-up was 3.4. Conclusions: Inflammatory arthritis in association with polyarteritis nodosa has a predilection to begin in the ankles and progresses to an oligoarthritis that can be difficult to treat with current immunosuppressive medications. Further research into the pathophysiology and treatment options of this oligoarthritis are indicated