Pseudorheumatoid progressive dysplasia (PRPD) is a hereditary, non-inflammatory skeletal disorder, autosomal, and recessive, associated to the WISP3. It is characterized by joint pain and effusion and progressively involves the hips, knees, wrists, and fingers. A reduction in joint mobility and multiple contractures lead to severe disability.

A 13-year-old male patient presented pain of the right hip and left knee which had started when he was 13. Five months later he presented swelling of both knees and the interphalangeal joints of the right hand. The patient referred a history of difficulty walking since he was 3 years of age. Upon examination we found a normal teenager with abnormal gait, spinal scoliosis, and kyphosis of the thoracic spine. Mobility of the lumbar spine, coxofemoral joints, knees, ankles, and interphalangeal joints were severely limited. X-rays of the hands and feet (Fig. 1a and b), hips and knees (Fig. 2a and b) revealed diffuse osteopenia, tubular widening of the epiphysis and loss of joint space, without erosive lesions; X-rays of the hip and knees also showed degenerative changes, with widening of the femoral heads. Thoracic and lumbar vertebrae were flattened and had an irregular surface (Fig. 3a and b). C reactive protein and erythrosedimentation rate were normal.

Fig. 1.

(a and b) Hand and feet X-rays show osteopenia, tubular epiphyseal widening and loss of joint space, without erosions.

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Fig. 2.

(a and b) Coxofemoral and knee X-rays show severe degenerative changes.

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Fig. 3.

(a and b) Flattened thoracic and lumbar vertebral bodies with irregularities of their surfaces (platyspondylia).

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PRPD clinically simulates early stages of JIA1,2; however, the evidence used to establish the diagnosis of bone dysplasia is non-inflammatory joint involvement and characteristic radiological findings, such as the presence of enlarged epiphyses, generalized osteoporosis, and platyspondylia.3

This disease is caused by mutations in the WISP 3 gene, essential for normal growth and postnatal skeletal and joint cartilage homeostasis.4 Therefore, in contrast to most of the skeletal dysplasias, prenatal skeletal growth and morphogenesis not altered in PRPD and affected individuals are asymptomatic during the first year of life. Subsequently, patients have progressive loss of joint cartilage and severe degenerative changes.4,5

The authors have no conflicts of interest to make.