Endocrine Abstracts

A rare skeletal dysplasia-Progressive Pseudorheumatoid dysplasia—close mimicker of juvenile idiopathic arthritis

Introduction: Progressive pseudorheumatoid dysplasia (PPD) or spondyloepiphyseal dysplasia tarda with progressive arthropathy (SEDT-PA) is a rare autosomal recessive arthropathy of childhood involving the entire skeleton. Here we report first genetically proven case of PPRD from the country. Often mistaken as juvenile rheumatoid arthritis, however, the joint problems in juvenile rheumatoid arthritis are associated with inflammation, while those in PPRD are not. The definitive diagnosis is established in a proband with characteristic radiologic findings and biallelic pathogenic variants in CCN6 (formerly WISP3) on genetic testing.

Case report: 7½ years old, vaccinated boy, having weight of 12.5 kg(SDS-3.0) and height of 104 cm(SDS -4.5) with normal vitals and no significant birth and developmental history, referred to our endocrine OPD for workup of short stature in 2019. He had restricted movements in small joints of hands bilaterally and painful right knee joint for last two years. Child had been extensively worked up for juvenile idiopathic arthritis and been given multiple oral NSAIDs. No familial disorder of joints or skeleton in the family. On examination a young cooperative boy of extreme short stature and lean built. His gait was normal with restricted movements in all PIP and DIP joints of bilateral hands and spindle shaped deformities of all fingers. Spine and TMJ were normal. His Hb was 11.9, TLC 9.1 and platelets were 361 with negative inflammatory markers including ESR and CRP. Serum biochemistry, renal functions and thyroid profile were within normal range. Screening for celiac disease TTg IgA and IgG were negative and he was found to be moderately growth hormone deficient on Insulin tolerance test (ITT).Skeletal survey showed large epiphysis and widened metaphysis of the metacarpals/metatarsal and phalanges of hands showing periarticular osteopenia without erosion. Spine radiographs showed inferior beaking, and platyspondyly typical for PPRD.fig Two pathogenic variants identified in WISP3 gene, confirming the diagnosis of PPRD.

Conclusion: Creating awareness regarding this rare form of skeletal dysplasia is crucial to avoid extensive workup and use of multiple drugs for JIA as well as to offer early management including orthopedic interventions.