MEFV mutations have been documented in patients with palindromic rheumatism (PR) who do not meet FMF criteria, and RF and ACPA positive RA may start with PR.

To analyze the clinical phenotype and disease evolution of patients with intermittent, palindromic-like (PL) arthritis seen in our Arthritis Unit according to the RF, ACPA and MEFV mutation status.

MEFV genotyping was done in 76 patients with PL arthritis as defined by predominantly short attacks (≤7days) and a relapsing course. Characteristics of arthritic episodes, RF and ACPA positivity, and the colchicine response were retrospectively collected. Patients were stratified and evaluated according to MEFV mutations and/or positive autoantibodies (ACPA and/or RF).

Among the patients, 26.3% (20/76) had a MEFV mutation and 23 (30%) were ACPA and/or RF positive. MEFV mutations and/or autoantibody status allowed four PL arthritis patients to be distinguished: group I (MEFV+), with younger age of onset, short duration attacks (<3days), mainly located in the knee, more frequent non-articular manifestations (fever, pericarditis or abdominal pain) and good response to colchicine; group II (autoantibody+) is older than group I, with the same frequency of short attacks, but the most affected joints were the wrists and small joints of hands: 48% met RA classification criteria during follow-up and were taking DMARDs; group III (MEFV− and autoantibody−) was the most frequent (48%) and clinically heterogeneous group; 51% had attacks lasting>3days, and 15 patients developed criteria of immune-mediated inflammatory, autoinflammatory or infectious diseases. Group IV (MEFV+ associated with preexisting immune-inflammatory disease), was associated with very short attacks, like groups I and II, superimposed or coincident with definite immune-inflammatory disease, including seropositive RA, with good response to colchicine.

Patients with PL arthritis can be classified in four groups according to the presence or not of MEFV mutations and ACPA/RF antibodies with a different clinical evolution and therapeutic response.