Dr.Jerin.K.John, Dr.Suma Balan (Ped Rheumat, AIMS), Dr.C. Jayakumar
An eight year-old boy initially presented with high-grade fever and progressive additive polyarthritis involving both large joints (knees, elbows, and ankles) and small joints of the hands. The pain was severe, with morning stiffness, restricted mobility, and tearfulness due to discomfort. During his hospital stay, significant synovitis was observed across multiple joints. Despite treatment with naproxen, the patient developed fever, but joint function and pain improved with ongoing therapy. There was no involvement of other systems
Mantoux testing and chest X-ray done were normal, ruling out tuberculosis.
On follow-up, the patient developed psoriatic changes on both feet, consistent with psoriatic arthritis.
Whole-body MRI revealed two Chronic recurrent multifocal osteomyelitis (CRMO)-type lesions—one in the left pubic bone adjacent to the symphysis and another in the posterior left acetabulum. These lesions appeared as (short T1inversion recovery )STIR-bright marrow hyperintense signals with no associated joint effusion, soft tissue changes, or areas of restricted diffusion.
No other bones or soft tissues showed abnormalities.
The laboratory investigations demonstrated mild elevation in inflammatory markers, with CRP ranging from 0.36 to 0.90 mg/L and ESR between 6 and 17 mm/hr. Liver enzymes (AST) were mildly elevated, peaking at 24.7 IU/L. Neutrophil counts fluctuated, reaching as high as 76.6%, with occasional mild anemiaand microcytosis.
Given the evolving clinical picture, the patient was initially treated with sulfasalazine (SAAZ) and Naproxen, which improved his joint symptoms. However, as the psoriatic changes progressed, treatment was escalated to methotrexate 15 mg weekly with folic acid 5 mg supplementation.
Differential Diagnosis
1. Juvenile Idiopathic Arthritis (JIA): Persistent polyarthritis with raised inflammatory markers, though the presence of CRMO-like bone lesions makes JIA less likely.
2. Psoriatic Arthritis: Suggested psoriatic changes on the feet, but this diagnosis alone does not explain the bone lesions typical of SAPHO.
3. Chronic Recurrent Multifocal Osteomyelitis (CRMO): Bone lesions are a characteristic feature, though arthritisand psoriatic changes align more with SAPHO syndrome.
4. Reactive Arthritis: Initially suspected due to the preceding fever and arthritis, but the chronic course and evolving symptoms do not fit the typical pattern of reactive arthritis.
5. SAPHO Syndrome: Best fits the clinical picture with polyarthritis, bone lesions, psoriatic changes, and acne.
Discussion
SAPHO syndrome (Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis) is a rare auto inflammatory condition that presents with a combination of arthritis, skin manifestations, and bone lesions. Its clinical presentation often overlaps with conditions such as psoriatic arthritis, CRMO, and reactive arthritis, making the diagnosis challenging.
In this case, the polyarthritis and CRMO-type bone lesions in the pubis and acetabulum are hallmark features of SAPHO. The presence of psoriatic changes on the feet and acne further supports the diagnosis, as skin involvement is a frequent component of SAPHO syndrome.
The syndrome typically follows a relapsing-remitting course, with arthritis and osteitis being the most persistent manifestations.
Bone lesions in SAPHO are often sterile, seen on imaging as hyperintense signals in marrow on STIR sequences, with little to no soft tissue involvement.
The absence of joint effusions or soft tissue collections, as noted in this patient’s MRI, is also typical of SAPHO.
Diagnosis of SAPHO syndrome is largely clinical, based on the combination of bone lesions, synovitis, and skin changes, as specific laboratory markers or diagnostic tests are not available. It is essential to differentiate SAPHO from other conditions like JIA, CRMO, and psoriatic arthritis, as management strategies differ.
Though SAPHO syndrome is chronic and may require long-term treatment, patients usually respond well to disease-modifying agents (DMARDs). The use of methotrexate is particularly effective for managing both arthritic and skin symptoms, as demonstrated in this case. Regular monitoring for flare-ups or the development of new lesions is crucial, as the disease can relapse. Timely and appropriate treatment is necessary to prevent joint damage and improve quality of life.
This case highlights the importance of recognizingSAPHO syndrome as a distinct clinical entity, especially in children presenting with arthritis, bone lesions, and psoriatic changes. Early diagnosis and tailored therapy are key to managing symptoms and preventing complications.