title: The clinical characteristics of sarcoid arthropathy based on a prospective cohort study.
abstract: BACKGROUND
  Sarcoidosis is known as a Th1-mediated disease, which can mimic many primary rheumatologic diseases or sometimes co-exist with them. Clinical characteristics of sarcoid arthropathy are not well described and the studies reported in the literature so far are mostly based on data from referrals. The aim of this study was to evaluate the incidence and clinical characteristics of sarcoid arthropathy.
  
  
  METHODS
  All our patients were prospectively evaluated in our rheumatology outpatient center from 2011 to 2015. A total of 114 (32 male) patients with sarcoidosis who were admitted to our clinic were included in the study. Clinical, demographical, laboratory, radiological and histological data of these patients obtained during 4-year follow-up and treatment period were compiled and analyzed.
  
  
  RESULTS
  The mean patient age was 48.1 years (range, 20-82 years), and the mean disease duration was 40.5 months (range, 1-300 months). Sarcoid arthritis was observed in 71 (62.3%), and arthralgia in 106 (92.9%) patients. Out of the 71 patients with arthritis, 61 (85.9%) had involvement of ankle, 7 (9.8%) knee, 2 (2.8%) wrist, MCP and PIP joints, and 1 (1.4%) had shoulder periarthritis. Oligoarthritis (two to four joints) was the most common pattern followed by monoarthritis and polyarthritis. Arthritis and erytjhema nodosum and arthritis and female sex was found to be correlated (p= 0.03 andp= 0.001). Again, in patients with arthritis, even higher levels of CRP/ESR as well as ANA and RF positivity were observed (p= 0.03,p= 0.01,p= 0.01, andp= 0.02, respectively). A total of 11 patients had another rheumatic pathology concurrent with sarcoidosis.
  
  
  CONCLUSIONS
  Inflammatory arthritis occurs in a majority of patients with sarcoidosis. Acute arthritis with bilateral ankle involvement is the most common pattern of sarcoid arthropathy. Sarcoidosis can mimic many primary rheumatic diseases or may coexist with them. Sarcoidosis should be considered not only as a mimicker but also as a Th1-mediated primary rheumatologic pathology.
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Istinye University, LIV Hospital, Istanbul, Turkey.
authors.forename: Senol
authors.initials: S
authors.lastname: Kobak
authors.affiliation: Department of Chest Diseases, Faculty of Medicine, Sifa University, Izmir, Turkey.
authors.forename: Fidan
authors.initials: F
authors.lastname: Sever
authors.affiliation: Department of Chest Surgery, Suat Seren Chest Diseases Hospital, Izmir, Turkey.
authors.forename: Ozan
authors.initials: O
authors.lastname: Usluer
authors.affiliation: Department of Chest Diseases, Faculty of Medicine, Ege University, Izmir, Turkey.
authors.forename: Tuncay
authors.initials: T
authors.lastname: Goksel
authors.affiliation: Department of Statistics, Faculty of Medicine, Ege University, Izmir, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Orman
keywords: arthropathy; incidence; sarcoidosis