title: Diagnostic dilemma of paraneoplastic arthritis: case series.
abstract: OBJECTIVE
  Paraneoplastic arthritis (PA) may mimic rheumatic diseases. While presenting the demographic and laboratory features of the patients diagnosed with PA, this study also aims to provide possible appropriate tools to differentiate the PA cases from early rheumatoid arthritis (ERA).
  
  
  METHODS
  Sixty-five patients with PA (male/female: 43/22) from 15 different rheumatology clinics and 50 consecutive patients with ERA (male/female: 13/37) fulfilling the 2010 American College of Rheumatology (ACR) criteria for the diagnosis if the RA from Gaziantep Rheumatology Early Arthritis Trial (GREAT) as controls who were diagnosed at least 12 months before, were enrolled into study.
  
  
  RESULTS
  Mean ages of the patients with PA and ERA were 50.2 ± 15.3, and 42.7 ± 12.3, respectively, and the mean ages of the patients with PA were significantly higher than the ERA. Unlike the ERA patients, in our case series PA was predominantly observed among males. Oligoarthritis was significantly higher in solid tumors in contrast to ERA (P = 0.001). Polyarthritis and symmetric arthritis were significantly higher in the ERA group in contrast to all malignancies (P = 0.001). Rheumatoid factor (RF) and anticyclic citrullinated peptide antibody (anti-CCP) positivity were significantly higher in the ERA group (each P = 0.001). Lactic dehydrogenase levels of hematologic malignancies were significantly higher than other groups (each, P = 0.001).
  
  
  CONCLUSIONS
  ERA patients had more symmetric joint involvement than PA; laboratory markers could be also an alternative where there is high RF and anti-CCP positivity with antibody levels among the ERA patients. Finally, the demographic features can be used as differentiating factors; ERA was seen predominantly among females aged 40-59 years which refers to young adults.
authors.affiliation: Department of Internal Medicine, Division of Rheumatology, Gaziantep University Faculty of Medicine, Gaziantep, Turkey.
authors.forename: Bunyamin
authors.initials: B
authors.lastname: Kisacik
authors.forename: Ahmet M
authors.initials: AM
authors.lastname: Onat
authors.forename: Timucin
authors.initials: T
authors.lastname: Kasifoglu
authors.forename: Yavuz
authors.initials: Y
authors.lastname: Pehlivan
authors.forename: Omer N
authors.initials: ON
authors.lastname: Pamuk
authors.forename: Ediz
authors.initials: E
authors.lastname: Dalkilic
authors.forename: Salim
authors.initials: S
authors.lastname: Donmez
authors.forename: Sule Y
authors.initials: SY
authors.lastname: Bilge
authors.forename: Sedat
authors.initials: S
authors.lastname: Yilmaz
authors.forename: Hakan
authors.initials: H
authors.lastname: Erdem
authors.forename: Ridvan
authors.initials: R
authors.lastname: Mercan
authors.forename: Mehmet A
authors.initials: MA
authors.lastname: Ozturk
authors.forename: Cemal
authors.initials: C
authors.lastname: Bes
authors.forename: Mehmet
authors.initials: M
authors.lastname: Soy
authors.forename: Sukran
authors.initials: S
authors.lastname: Erten
authors.forename: Veli
authors.initials: V
authors.lastname: Cobankara
authors.forename: Soner
authors.initials: S
authors.lastname: Senel
authors.forename: Fatma A
authors.initials: FA
authors.lastname: Oner
authors.forename: Haner
authors.initials: H
authors.lastname: Direskeneli
authors.forename: Sema
authors.initials: S
authors.lastname: Yilmaz
authors.forename: Ayten
authors.initials: A
authors.lastname: Yazici
authors.forename: Hakan
authors.initials: H
authors.lastname: Emmungil
authors.forename: Kenan
authors.initials: K
authors.lastname: Aksu
authors.forename: Seval
authors.initials: S
authors.lastname: Kul
authors.forename: Gozde Y
authors.initials: GY
authors.lastname: Cetin
authors.forename: Mehmet
authors.initials: M
authors.lastname: Sayarlioglu
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001168:Arthritis / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007596:Joints / Q000473:pathology; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008297:Male; D008875:Middle Aged; D010257:Paraneoplastic Syndromes / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D010456:Peptides, Cyclic / Q000276:immunology; D011237:Predictive Value of Tests; D012217:Rheumatoid Factor / Q000097:blood; D016896:Treatment Outcome; D014421:Turkey
chemical_list: D018501:Antirheumatic Agents; D015415:Biomarkers; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor; D007770:L-Lactate Dehydrogenase
keywords: early rheumatoid arthritis; malignancy; paraneoplastic arthritis