Table 2 Clinician, molecular and radiological comparison between JIA and JIA mimics to aid differentiation
From: Monogenic disorders as mimics of juvenile idiopathic arthritis
Condition | Characteristics | Inheritance | Typical age of onset (years) | Typical inflammatory markers (normal or raised) | Physical examination | Typical Image findings |
|---|---|---|---|---|---|---|
JIA | Arthritis lasting > 6 weeks | Multifactorial | Childhood (< 16) | Raised | Soft tissue swelling Stiffness (mainly morning) Warmth to touch Painful ROM of affected joints Small and large joints affected | x-ray findings - soft tissue swelling, loss of joint spaces, osteopenia, erosions, growth disturbances, joint subluxation (1) US findings – synovial proliferation, joint effusions MRI findings – synovitis, bone erosion, bone marrow oedema, enhancement (2) |
MCTO | Osteolysis of Carpo-tarsal bones renal failure +/− Corneal clouding +/− Craniofacial abnormalities +/− Other manifestations ie skin changes +/− | AD | <  1 | Normal | Deformity of hands and feet Stiffness and restriction in ROM in hands and feet | x-ray – progressive destruction of the carpal and tarsal bones |
CACP | Camptodactly Arthropathy Coxa vara Pericarditis | AR | <  1 | Normal | Fixed flexion deformity of the proximal interphalangeal joints (most commonly affecting the 5th digit) Limitation in ROM of the hips and knees | x-ray - bilateral coxa vara with shallow acetabular and periarticular osteopenia Large acetabular cysts US - bilateral effusions of large joints - hips and knees Prominent synovial proliferation with normal synovial vascularity MRI - short and broad femoral necks with minimal enhancement with ring pattern, synovial thickening |
Blau syndrome | Granulomatous, arthritis, uveitis & dermatitis Visceral involvement +/− | AD | <  4 | Raised | Painful ROM of affected joints Joint swelling Skin changes Ocular symptoms | x-ray - osteopenia, joint space narrowing with no erosions, typically symmetrical (3) |