Progressive pseudorheumatoid dysplasia (PPRD) is a rare autosomal recessive skeletal dysplasia with an incidence of 1 per 1 million that occurs due to the mutations in the WNT1-inducible-signaling pathway protein 3 (WISP3; also known as CCN6) gene. It is characterized by progressive, noninflammatory osteochondrodysplasia, which results in joint stiffness, pain, enlargement, contractures, spinal deformities, short stature, and gait abnormalities.1,2
A 20-year-old woman presented with a 5-year history of progressive low back and hip pain, without morning stiffness or nocturnal pain. She gradually developed pain and swelling in the bilateral proximal interphalangeal joints, knees, and ankles, accompanied by a waddling gait and restricted neck movement. Her family history was unremarkable. She was initially diagnosed with spondyloarthritis and osteoarthritis based on magnetic resonance imaging (MRI) findings showing mild bone marrow edema in the right sacroiliac joint and hyperostosis of the hip. Despite treatment with nonsteroidal antiinflammatory drugs and traditional Chinese medicine (such as white peony root, clematis root, divaricate saposhnikovia root, and angelica root), her symptoms progressed. Physical examination revealed restricted neck and bilateral hip mobility. Schöber test measured 2 cm and bilateral Patrick tests were negative. Laboratory investigations showed normal levels of C-reactive protein, erythrocyte sedimentation rate, HLA-B27, rheumatoid factor, anticyclic citrullinated peptide antibody, and antinuclear antibody. The radiograph demonstrated mild straightening in the cervical spine. Thoracic and lumbar spines showed platyspondyly, reduced intervertebral disk spaces, and kyphosis (Figure 1A). Bilateral hips revealed hyperostosis and joint space narrowing, and the right sacroiliac joint showed mild osteosclerosis (Figure 1B). Shoulder and knee radiographs showed osteophytes, joint space narrowing, and sclerosis. MRI showed flattening and defects of the lumbar spine vertebrae. Hip MRI revealed bone marrow edema and cystic changes. Genetic analysis identified 2 heterozygous mutations in the CCN6 gene: c.346+5(IVS2) G>C and c.221(exon2) G>A (Supplementary Figure S1, available with the online version of this article), confirming a diagnosis of PPRD with limited effective therapeutic options.3 Although rare and lacking specific early signs, a previous study identified genu varum deformity as an initial sign in early-onset PPRD. PPRD should also be considered with radiological findings like metaphyseal irregularity, widened tibial/distal radial-ulnar metaphyses, and genu varum.4
Radiographic features in progressive pseudorheumatoid dysplasia. (A) Lumbar vertebrae show anterior endplate erosions and narrow intervertebral spaces, especially centrally and posteriorly. (B) Pelvis demonstrates bilateral hip joint space narrowing, osteophyte formation, and mild sacroiliac joint osteosclerosis.
Footnotes
S. Zheng and Z. Xu contributed equally to this work as co-first authors.
CONTRIBUTIONS
SZ, GD, and YW drafted and revised the manuscript. SZ and ZX collected clinical/imaging data and prepared the figure. All authors reviewed and approved the final manuscript.
FUNDING
No specific funding was received from any bodies in the public, commercial or not for profit sectors to carry out the work described in this article.
COMPETING INTERESTS
The authors declare no conflicts of interest relevant to this article.
ETHICS AND PATIENT CONSENT
Institutional review board approval was not required according to the authors’ institution. Patient consent was obtained directly from patient.
DATA AVAILABILITY
Data sharing is not applicable to this article as no new data were created or analyzed in this study.
- Copyright © 2026 by the Journal of Rheumatology
SUPPLEMENTARY DATA
Supplementary material accompanies the online version of this article.
