On the other hand, there were 6/13 (46.2%), 10/13 (76.9%), 12/13 (92.3%), and 0/13 (0.0%) with CK7-positive, CK20-positive, CDX-2-positive, and GCDFP-15-positive in the secondary PPD cases, respectively. This evidence concerns the gene KRT20 and progressive pseudorheumatoid arthropathy of childhood.