Acute rheumatic fever classically involves large joints of lower or upper limbs referred to as fleeting migratory polyarthritis .But this pattern is not exclusive. In fact acute rheumatic fever commonly present with atypical features .The incidence can be up to 25 % in various series .The most surprising thing is , it can involve spinal as well as hip joints . Mono arthritis is also possible.
The only contention is , atypical features are frequently labelled by some as post streptococal reactive arthritis instead of rheumatic fever .
It is pure semantics at play . Whether you agree with the terminology or not , never hesitate to diagnose rheumatic fever when the joint involvement is atypical . If you ignore this you are bound to be guilty for damaging few hearts later.
What are the unusual joint involvement in acute rheumatic fever ?
- Small joints of the feet
- Small joints of the hands
- Cervical spine
- Thoracic spine
- Lumbar spine
The involvement of above joint can be up to 25%
Here is an excellent paper from Brazil about the huge variation in the pattern of joint involvement in acute rheumatic fever.