Clinical characteristics of pustulotic arthro-osteitis in Korea.

Pustulotic arthro-osteitis (PAO) has been studied primarily in Japan. However, there is a lack of research regarding its clinical features among large populations in other countries and it is often believed to be similar to psoriatic arthritis (PsA). Although the association between psoriasis (PsO) and palmoplantar pustulosis (PPP) is debatable, differences in the clinical characteristics between PsA and PAO might support the notion that PsO and PPP are distinct entities. This study aimed to investigate the clinical characteristics of PAO in Korean patients and to compare them with those of PsA. We retrospectively reviewed the medical records of patients diagnosed with PPP, PAO, and PsA. Among 266 patients with PPP, 13.2% had PAO. Unlike Japanese patients with PAO, Korean patients had a relatively lower involvement of the chest wall. PAO patients demonstrated lower age of onset, higher proportion of females, and higher severity of cutaneous eruptions compared to PPP patients without PAO, but the differences were not statistically significant. Female predominance was prominent in PAO compared to PsA. Cutaneous eruptions occurred earlier than joint symptoms in 83.5% of the patients with PsA and in 42.9% of the patients with PAO. PAO involved axial joints more frequently compared to PsA, especially the chest wall and spine. PsA mainly involved the peripheral joints, especially the metacarpophalangeal joints and distal interphalangeal joints of the hands and feet. In conclusion, PAO and PsA exhibited different demographics and locations of joint involvement, supporting the notion that PPP and PsO are separate disorders. Many PAO patients presented with joint symptoms before the appearance of skin eruptions, underlining the important role of dermatologists in recognizing PAO among PPP patients. Physicians should be aware of the characteristics of PAO while treating patients with PPP.