Undifferentiated connective tissue disease: the diagnoses critically revised-experience of a single center

Although anti-nuclear antibodies (ANA) are considered the main entry criteria for a diagnosis of undifferentiated connective tissue disease (UCTD), many patients show different rate of ANA positivity and questionable diagnoses. Aim of the study was to revise the UCTD diagnoses and analyse the main predictors of evolution in a monocentric cohort. We retrospectively revised the diagnoses of 331 ANA positive patients, with at least one year of follow-up, classified as UCTD from 2009 and 2017. The diagnosis of UCTD was confirmed in 180 cases (54.4%). The evolution occurred in 18% of cases, after a follow-up of 6.9 (SD: 4.4) years. Raynaud's phenomenon (RP) (OR: 2.39), puffy hands (OR: 6.3), anti-ENA (OR: 2.34), anti-Topoisomerase I antibodies (OR: 4.93), rheumatoid factor (RF) (OR: 2.86) were associated with evolution. Evolution in Systemic Lupus Erythematosus (SLE) occurred in 5 patients (2.78%) and associated with the addition of new autoantibodies, compared with other evolutions (p: 0.034; OR: 12; 95CI: 1.4-103.4). Evolution in Systemic Sclerosis and pSS was found in 14 (7.8%) and 8 cases (4.4%), respectively. Puffy hands and RF positivity as the predictors of SSc and pSS evolution, respectively. A confirmed diagnosis of UCTD, according with the available criteria, was assessed in about a half patients. The occurrence of puffy hands since the onset defines a patient with a potential evolution into SSc, while the addition of new specific autoantibodies represents a typical "fingerprint" of patients developing SLE.