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Swollen Joints & Malaise

Bone and Joint infections in an Immunocompromised Host

Selena is a 6 year old girl with Juvenile idiopathic Arthritis (JIA). She first presented with swollen knees followed by a swollen elbow. She was treated with NSAIDS and intraarticular corticosteroid injections. Six months later she had a recurrence of swollen knees and elbows and was started on Methotrexate subcutaneous weekly.  Unfortunately, due to family problems, she left her home to stay with her elderly grandfather in the Philippines and was lost to follow up for 4 months. When she returned home, she was still noted to have one swollen knee, and a painful lump on her calf. Ultrasound of the knee showed an effusion, with septations and a Baker’s cyst. Additionally, she was having fatigue, a mild cough and had not gained weight since her last appointment.  

What diagnostic testing would you do?

Full Blood Count showed a differential WBC of 11.0  x 106/L with a neutrophil predominance, mild anaemia with a normal MCV, and normal platelet count.  A CRP was 50 (normal <10mg/L) and an ESR was 80 (normal 0 to 15 mm/hr).

What is the differential for recurrent swollen knee after intraarticular corticosteroids and Methotrexate injections?

Arthritis that is poorly controlled even on Methotrexate, infections, trauma, vascular malformations.

Which aspects of the history narrow the differential and what are the red flags?

The fatigue, cough and lack of weight gain in addition to the high CRP and ESR are concerning for an infection.  Trauma and vascular malformation are unlikely to cause the cough and fatigue, or the abnormal inflammatory markers.  Poorly controlled arthritis in one knee should not be associated with a cough, or poor weight gain and usually, the inflammatory markers are not markedly abnormal.

What should be done next?

A joint aspiration was done which showed a thick, purulent looking synovial fluid.  Gram stain showed acid fast bacilli. A CXR showed miliary tuberculosis (TB) of the lungs. 


JIA with disseminated TB.  Children who are on DMARDs or biologics and live in or travel to regions where TB or other infections are endemic, should have a workup for infection. Children who are immunosuppressed with medications may have a muted response to infection, hence one has to be more careful in looking for occult infection.