Objective. - To individualize a new clinical entity of chronic arthritis and/or a factor indicating good prognosis of chronic arthritis.

Methods. - We retrospectively studied 12 cases of monoarthritis or oligoarthritis that met none of the criteria sets for known diseases, even after more than 10 years of follow-up.

Results. - Features in these 12 patients included recurrent effusions of inflammatory joint fluid consistently showing a predominance of lymphocytes and monocytes, long periods of remission separating the flares, absence of clinical or radiological joint lesions despite prolonged follow-up (10-40 years), an excellent response to joint aspiration and intraarticular glucocorticoid injection, unresponsiveness to second-line drugs, and young age at onset. Males and females were equally affected. Absolute lymphocyte/monocyte counts in joint fluid were similar in the 12 study patients and in 59 patients with rheumatoid arthritis, whereas absolute and differential neutrophil counts were significantly lower in the study patients.

Conclusion. - The above-described features and excellent functional outcome suggest that this clinical pattern may deserve to be viewed as a separate entity. We suggest the name “idiopathic lymphomonocytic arthritis” or, since a low-neutrophil count in joint fluid was also a conspicuous finding, “Flory syndrome”, Flory being the name of the first patient in our series.