title: Erosive discovertebral lesion (Andersson lesion) as the first sign of disease in axial psoriatic arthritis.
abstract: OBJECTIVE
  To present two cases of Andersson lesion (AL) as the form of onset of psoriatic arthritis (PsA), to review the form of onset of axial disease in PsA in our area, and to study the prevalence of AL in this series.
  
  
  METHODS
  Two patients with psoriasis and recent-onset inflammatory back pain (IBP) with no known arthritis are presented. A final diagnosis of AL based on magnetic resonance imaging (MRI) findings was made. The medical records of 120 consecutive patients with axial PsA were reviewed and the most relevant features at disease onset analysed.
  
  
  RESULTS
  Including the two cases presented, an AL prevalence of 5.7% was found in this series. The most common onset forms of axial PsA were: oligoarthritis (30%), IBP (21.7%), enthesitis (17.5%), polyarthritis (16%), gluteal pain (8.3%), dactylitis (3.3%), and distal interphalangeal (DIP) involvement (3.3%). Compared to women, men more frequently showed enthesitis (25% vs. 9%, p = 0.03) and IBP (31% vs. 10.7%, p = 0.007) as onset forms whereas a polyarticular onset was predominant in women (25% vs. 8%, p = 0.01). The polyarticular onset was predictive of radiological damage in the cervical column during follow-up [odds ratio (OR) 2.6, 95% confidence interval (CI) 1.82-6.83, p = 0.01]. Enthesitis (23.6% vs. 8.3%, p = 0.02) and IBP (29.7% vs. 10.4%) were the predominant onset forms in patients with age at disease onset ≤ 40 years and polyarthritis (27% vs. 8.3%, p = 0.009) was predominant in those with disease onset > 40 years.
  
  
  CONCLUSIONS
  AL is an uncommon finding in axial PsA and its appearance at disease onset is exceptional. MRI is a key tool in its early recognition.
authors: Department of Rheumatology, HUCA, Central University Hospital of Asturias, Oviedo, Spain. rubenque7@yahoo.es
authors: R
authors: R
authors: Queiro
authors: P
authors: P
authors: Tejón
authors: S
authors: S
authors: Alonso
authors: M
authors: M
authors: Alperi
authors: J
authors: J
authors: Ballina
mesh_terms: D000328:Adult; D015535:Arthritis, Psoriatic / Q000473:pathology*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D013166:Spondylitis / Q000473:pathology