Differential diagnosis of the rash and musculoskeletal symptoms considered at morning ward round
Differential diagnosis | Factors supporting this diagnosis | Factors not supporting this diagnosis |
---|---|---|
Rheumatic diseases | ||
Pauciarticular juvenile idiopathic arthritis (JIA) | Lymphadenopathy is sometimes present in JIA | The diagnosis of JIA is based on the physical finding of arthritis (or synovitis) in at least one joint that persists for at least 6 weeks, with other causes being excluded. Typically knees ankles and wrists are affected Rash is “salmon pink” There is often hepatosplenomegaly in JIA |
Elevated ESR | ||
Systemic lupus erythematosis | Fever | Arthralgia that is not episodic |
No malar rash | ||
Vasculitis | ||
Kawasaki disease | Fever, rash (although not polymorphic) and lymphadenopathy | No stomatitis |
No conjunctivitis | ||
Fever duration <5 days | ||
Serum sickness | Acute onset | No recent medications |
Fever | Rash not urticarial | |
Henoch-Schlonlein purpura | Rash not purpuric | |
High fever unusual | ||
Bacterial infection | ||
Septic arthritis | Elevated ESR, C-reactive protein | Ultrasound normal, blood culture negative (but only positive in 30% of cases) |
Osteomyelitis | Elevated ESR in 90% | Ultrasound not showing elevation of the periosteum (may be seen in experienced hands within the first week) |
Elevated CRP in 98% | ?need for bone scan to exclude this diagnosis but no bony tenderness noted | |
(Normal x ray compatible as x ray remains normal until >50% bone has been demineralised) | ||
Viral infection | ||
Rubella | MMR vaccine up to date | |
Rash not typical | ||
Parvovirus B19 | Arthralgia usually symmetric, involving hands, wrists, knees, and feet; arthralgia not symmetrical in this case Erythema infectiosum (fifth disease) characterised by a erythematous malar rash (slapped cheek) and a reticulated lace like rash on the extremities | |
Rash not typical | ||
Fever did not resolve when rash appeared | ||
Hepatitis viruses | Never had a blood transfusion | May get arthritis with hepatitis B |
Post-infectious | ||
Rheumatic fever | May have some minor criteria—fever, arthralgia, and raised acute-phase reactants. Perhaps the rash is erythema marginatum? | No carditis |
No chorea | ||
No subcutaneous nodules | ||
No polyarthritis | ||
Reactive arthritis | No history of sore throat, no hepatosplenomegaly, no diarrhoea, no compatible rash | |
Neoplastic | ||
Acute leukaemia | No haematological abnormalities |