39 Pediatric monoarthritis of the elbow: atypical onset of a common disease

Abstract

Abstract Background Oligoarticular type of juvenile idiopathic arthritis (oligoJIA) is considered the most common type of JIA. It usually affects one or < 4 joints. The knee is the most common affected joint followed by the ankle and wrist. Oligoarticular JIA presenting with erosive elbow monoarthritis as an initial sign of the disease is a rare condition which needs prompt diagnosis and management. Objective To recognize that isolated chronic elbow monoarthrits is an atypical presentation for oligoJIA. Case presentation: A 14-year-old volleyball player female child presented with chronic recurrent left elbow swelling of six months’ duration. No history of morning stiffness, constitutional symptoms, other joint swelling, uveitis, or skin manifestations were reported. On examination there was mild cubitus valgus with elbow effusion associated with limited last degree elbow extension with no other signs of inflammation or infection (redness, tenderness, hotness). Hypermobility was noted in both elbows and knees. Patient was advised to rest the elbow and symptomatic treatment was recommended. On follow up there was mild improvement of the swelling, so further investigations were ordered. Erythrocyte Sedimentation Rate (ESR), C-reactive protein (CRP), Rheumatoid factor (RF) and antinuclear antibody (ANA) showed average normal values. X-ray of the elbow showed degenerative changes. Musculoskeletal ultrasound showed mild elbow effusion and magnetic resonance imaging (MRI) was ordered revealing effusion and early joint erosion at the ulnar articular surface with no synovial hypertrophy. Arthroscopy was recommended to detect the underlying pathology and histopathology revealed chronic active synovitis suggesting JIA. Non-steroidal anti-inflammatory drugs (NSAIDs) were recommended but one month later knee arthritis was noted, so methotrexate was started and the condition started to improve. Results We report a 14-year-old female child who presented with atypical isolated chronic swelling of the elbow and was diagnosed by arthroscopy and histopathology. Non-steroidal anti-inflammatory drugs (NSAIDS) were tried as a first line treatment followed by methotrexate. Conclusion Chronic elbow monoarthritis is an atypical onset of oligoJIA and its diagnosis is important to prevent irreversible joint damage. Synovial biopsy can have a major role in the diagnosis of atypical monoarticular JIA and can help in early diagnosis and management improving the outcome. The implication to policy, practice, research, and advocacy: Monoarthritis of the elbow as initial sign of oligoJIA is an atypical onset of this disease and in the absence of systemic signs or other clinical indicators determining the exact cause of monoarthritis in children might be difficult. Synovial biopsy can have an important role in the diagnosis of monarticular arthritis in pediatric patients.