Triggering role of focal infection in the induction of extra-palmoplantar lesions and pustulotic arthro-osteitis associated with palmoplantar pustulosis.

Palmoplantar pustulosis (PPP) is a chronic inflammatory disorder characterized by sterile pustules predominantly involving the palms and soles of middle-aged women. Whether PPP is the acral type of pustular psoriasis or a distinct entity has long been discussed; however, the clinical features of PPP are really heterogeneous and different between Asians and Caucasians, which may depend on the race with backgrounds of different HLAs. PPP is closely related with psoriasis, but considered to be a distinct entity in Japan. Although the pathogenesis of PPP is still poorly understood, PPP is a representative skin disorder showing a close relationship with focal infections such as tonsillitis, chronic sinusitis, and dental infection. In particular, tonsillitis often triggers or deteriorates PPP. In Japanese patients, regions other than the palms and soles are occasionally affected manifesting scaly erythemas which resemble psoriasis, and solitary pustules are also seen. Some of these extra-palmoplantar lesions are induced by the Koebner phenomenon or occur after focal infections. Further, arthralgia is also induced on the sternum, clavics, sacroiliac joints, and upper ribs following focal infections. This paper makes a focus on the triggering role of focal infection in the induction of extra-palmoplantar lesions as well as arthralgia (putulotic arthro-osteitis).