Background: Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in childhood and is of unknown aetiology. Progressive pseudorheumotoid dysplasia is a rare, autosomal recessively inherited, non-inflammatory musculoskeletal disorder caused by mutations occurring in the WISP3 gene. Joint cartilage is the primary site of involvement, leading to arthralgia, joint stiffness, contractures, enlargement of the epiphyses and metaphysis of the hand joints, spinal abnormalities, short stature, early osteoarthritis, and osteoporosis. The clinical features resemble juvenile idiopathic arthritis (JIA), and patients with PPD are usually misdiagnosed as JIA.
Case Presentation: A 13 year old female presented to the rheumatology clinic with history of joint pains, bone pains and bone deformity for 5 years. Weight and Height were below the 3rd centiles. There was none tender swelling of metacarpophalangeal and interphalangeal joints and with scoliosis. Radiographs of the hands revealed widening of the epiphyses. With these findings Progressive Pseudorhematoid Dysplasia was suspected and genetic testing for WISP1, WISP2 and WISP3 was requested. A homozygous, likely pathogenic, variant was identified in WISP3 gene which confirmed our diagnosis.
Conclusion: Progressive Pseudorhematoid Dysplasia is a rare form of spondylo-epi-metaphyseal dysplasia and clinically misdiagnosed as Juvenile Idiopathic arthritis. It’s important to consider PPD especially in patients with normal inflammatory markers who are being followed up for arthritis and not improving on anti-rheumatic intervention.