Progressive pseudorheumatoid arthropathy of childhood (PPAC) is an inherited autosomal recessive skeletal dysplasia. The disease is associated with mutations of the gene WISP 3. Primarily it is a disorder of articular cartilage, followed by degeneration and loss of articular cartilage. The initial clinical symptoms, which usually appear between 3 and 8 years of age, are similar to the symptoms of juvenile idiopathic arthritis. The main features are progressive, non inflammatory arthropathy of minor and major joints and changes in the spine. Gradually there occurs enlargement of joints, then progressive restriction of joint and spine mobility. Radiographic imaging, the most important for diagnosis, revealed widened epiphyses and metaphyses of bones, generalized osteoporosis of bones, and narrowing of articular spaces. In the spine platyspondyly and narrow intervertebral disc spaces are typical. In differential diagnosis it is essential to exclude juvenile idiopathic arthritis, but also other connective tissue diseases, spondyloarthropathies, mucopolysaccharidoses, and inherited bone dysplasias.