Objective: To present four related patients with progressive pseudorheumatoid dysplasia (PPsRD) each with distinctive history, unique phenotype and some peculiar radiographic findings.
Results and conclusions: The history was characterised by weather-dependent articular pain. The unique phenotypic features were hypoplasia/dysplasia of one or two toes. Peculiar radiographic findings were hypoplasia of the 3rd and 4th metatarsals, platyspondyly with rectangular shape of the lumbar spinal canal, progressive narrowing of the joint spaces and early synovial chondromatosis. Finally, the condition was inherited as a dominant trait. This constellation of abnormalities constitutes a distinct form of PPsRD. PPsRD must be differentiated from other bone dysplasias, specifically spondyloepiphyseal dysplasias, autosomal dominant spondylarthropathy, juvenile rheumatoid arthritis and osteoarthritis.