Background Fibromyalgia (FM) is a frequent cause of chronic widespread pain (CWP). Although its occurrence in psoriatic subjects represents a clinical challenge in terms of diagnosis and management, such issue is still poorly investigated.

Objectives Our aim was to describe the features of CWP syndromes in a series of patients wild mild psoriatic subjects and to compare the existing classification criteria for FM.

Methods In a cohort of psoriatic patients followed in a dermatological clinic dedicated to psoriasis care, 307 were consecutively enrolled for an epidemiological study. Patient on biological treatment and those unable to give informed consent were not eligible.

All candidates underwent a thorough rheumatological evaluation. Details about history of pain and somatoform symptoms (SS) were collected as well. Imaging and laboratory investigations were performed as needed. Diagnosis was established through expert opinion.

Results The 307 studied patients had mean age of 53.8 years (SD 16.4); 188 (61.2%) were males. Median psoriasis duration was 11 years (IQR 4.5-20), median PASI score was 3.1 (IQR 1.6-6.5). Systemic therapies were prescribed to 91 (29.6%) subjects.

Chronic pain history was reported by 151 patients (49.2%), in 34 (11.1%) cases it was widespread. Median number of SS was 2 (IQR 1-3), median SS scale score was 2.5 (IQR 1-4).

Pain on examination was observed in 105 patients (34.2%) and it was widespread in 13 (4.2%) cases. Two hundreds-forty-eight subjects (80.8%) had no tender point.

In this series, 21 patients (6.8%) were diagnosed as CWP syndromes, only 3 satisfied the 1990 ACR criteria for FM (sensitivity 14.3%), 9 satisfied the 2010 criteria (sensitivity 42.9%), none satisfied both, 8 cases were close to satisfy at least one set of criteria. CWP syndromes were more frequent in females (P<0.001), but there was no difference in terms of age, psoriasis duration or PASI score from the rest of studied patients.

Scores of SS scale, WPI, tender points, reported or objective widespread pain were significantly more frequent (all P<0.001) in CWP syndrome patients. After logistic regression analysis only the number of SS (OR 54.7, 95% CI 1.4-2076.8; P=0.03) and reported widespread pain (OR 178.8, 95% CI 1.7-18533; P=0.02) remained significant. ROC curve analysis of SS yielded AUC=0.95 with a cut off of 4 (sensitivity 80.4%, specificity 93%).

Conclusions In this study, CWP was not common in psoriatic patients. The more recent classification criteria for FM proved to be were more sensitive than the older criteria, but problems of classification with borderline cases remained. The number of SS correlates well with CWP syndromes, representing a potential help in the diagnostic work up.

Disclosure of Interest None Declared