How does the number of affected joints help in sorting through the differential diagnosis of arthritis?
Factors helpful in assessing the etiology of arthritis are the duration of disease at the time the child is evaluated, the sex and age of the child, and the onset type and pattern of joint involvement. The differential diagnosis of polyarthritis is considerably different from that of monoarthritis or oligoarthritis. JIA is the most common cause of chronic monoarthritis, especially in girls aged <5 years.
Causes of Acute and Chronic Monoarthritis and PolyarthritisAdapted from Cassidy JT, et al: Textbook of Pediatric Rheumatology, 6th ed. Philadelphia, WB Saunders, 2011.
| Monoarthritis | Polyarthritis | |
|---|---|---|
| Acute monoarthritis | Chronic monoarthritis | |
| Early rheumatic disease | JIA | Polyarticular JIA (RF+, RF–) ERA |
| Oligoarticular JIA | ERA | Juvenile psoriatic arthritis |
| ERA | Juvenile psoriatic arthritis | SLE |
| Arthritis related to infection | Oligoarticular | MCTD |
| Septic arthritis | Sarcoidosis | Sjogren syndrome |
| Reactive arthritis | Infection | Polyarthritis related to infection |
| Lyme disease | Tuberculosis | Rheumatic fever |
| Malignancy | Lyme disease | Reactive arthritis |
| Leukemia | Hemarthrosis | Lyme disease (rarely) |
| Neuroblastoma | PVNS | Mucopolysaccharidoses |
| Hemophilia | Hemophilia | Pseudorheumatoid chondrodysplasia |
| Traumatic | Hemangioma | Sarcoidosis |
| Gout | Noninflammatory | |
| Synovial chondromatosis | ||
| Internal derangement | ||
| Lipomatosis arborescens | ||
| Lymphangioma |
ERA, enthesitis-related arthritis; JIA, juvenile idiopathic arthritis; MCTD, mixed connective tissue disease; PVNS, pigmented villonodular synovitis; RF, rheumatoid factor; SLE, systemic lupus erythematosus.
