Sir,Pustulotic arthro-osteitis (PAO) is associated with palmoplantar pustulosis (PPP),[1] which was estimated to be nearly 10% in PPP;[2] however, data regarding its frequency are still few. Anti-cyclic citrullinated peptide (anti-CCP) antibody is rarely detected in rheumatic disorders other than rheumatoid arthritis (RA).[3] We have aimed to determine the frequency of PAO among PPP patients, and the prevalence of anti-CCP antibody in PAO.We retrospectively examined the ratio of PAO and the presence of anti-CCP antibody in 134 patients with PPP who visited our department in these 7 years. Among them, 38 patients (28.4%) were diagnosed with PAO, which was assessed by the presence of joint pain and bone scintigraphy. The age range was 23–80 years (mean age 51.7 ± 9.7) and the female-to-male ratio was 3.75:1. All patients had typical PPP limited to the palms and soles, without extra palmoplantar skin lesion involvement. Among the 38 PAOpatients, anti-CCP antibody was examined in 35 cases using ELISA. Only three of them (7.9%) showed titers beyond the cut-off value (<4.5 U/ml) [Table 1]. Case 1 was a 43-year-old woman who was diagnosed with PPP 6 years ago. She had developed several tender and swollen sternoclavicular, shoulder and waist joints 2 months prior to diagnosis. Laboratory studies showed negative rheumatoid factor, increased level of anti-CCP antibody (7.1 U/ml), and anti-streptolysin O (ASO) (285 IU/ml, normal <244). Otological and dental examination did not find any focal infections. Case 2 was a 43-year-old woman with a 3-year history of intermittent pain of the right shoulder, who had vesiculopustular lesions on the palms and soles. Laboratory examination showed increased levels of white blood cell (10,600/μl), C-reactive protein (CRP: 0.38 mg/dl), and anti-CCP antibody (4.7 U/ml); however, ASO titers were within the normal range. Otological examination revealed swelling and enlargement of the tonsils. Tonsillectomy was recommended, but she selected to be treated with conservative treatment. Case 3 was a 70-year-old woman who was diagnosed with PPP 5 years ago. Pain of sternoclavicular and fifth thoracic vertebra joints appeared 3 months after the onset of PPP. CRP (0.77 mg/dl) and anti-CCP antibody (7.4 U/ml) values were elevated. Dental radiography showed chronic periodontitis.
Table 1
Analysis of characteristic features in the presence of anti-cyclic citrullinated peptide in patients with pustulotic arthro-osteitis
Analysis of characteristic features in the presence of anti-cyclic citrullinated peptide in patients with pustulotic arthro-osteitisOur results have demonstrated that more than 25% of patients with PPP have arthro-osteitis, which was much higher as compared with previous studies.[2] One reason is that our hospital is a university hospital and many PPP patients with refractory arthritis are referred; therefore, a bias may exist. Alternatively, PAO has become well known, and thus a large number of possible or occult patients are now being referred than previously. Other than RA, anti-CCP antibody becomes positive in almost 10% of patients with psoriatic arthritis[45] whereas PAO showed lower ratio of anti-CCP antibody with only low titers in this study. Serum CRP and matrix metalloproteinase-3 levels were not found to be associated with anti-CCP antibody levels in the three patients. In conclusion, we have demonstrated (i) a higher ratio of PAO in PPP (28.4%) than previous studies and (ii) a lower prevalence of anti-CCP antibody (7.9%) in PAO.