I first looked at PSA and saw this and then went to SAPHO Syndrome....very interesting.
Acne and nail changes are commonly seen in psoriatic arthritis. Pitting and ridges are seen in fingernails and toenails of 80% of patients with psoriatic arthritis. Interestingly, these characteristic nail changes are observed in only a minority of psoriasis patients who do not have arthritis. Acne has been noted to occur in higher frequency in patients with psoriatic arthritis. In fact, a syndrome exists that features inflammation of the joint lining (synovitis), acne and pustules on the feet or palms, thickened and inflamed bone (hyperostosis), and bone inflammation (osteitis). This syndrome is, therefore, named by the eponym SAPHO syndrome