How is Adult-onset Stills Disease diagnosed?

Diagnosis of Adult-onset Still's Disease

Adult-onset Still's Disease (AOSD) is a rare systemic inflammatory disorder characterized by high spiking fevers, rash, joint pain, and other systemic symptoms. Diagnosing AOSD can be challenging due to its nonspecific symptoms and the absence of specific diagnostic tests. However, a combination of clinical evaluation, laboratory tests, and exclusion of other conditions can help in reaching a diagnosis.

Clinical Evaluation

The first step in diagnosing AOSD involves a thorough clinical evaluation by a healthcare professional. The doctor will review the patient's medical history, including symptoms, duration, and any previous episodes. They will also perform a physical examination to assess the presence of characteristic signs such as fever, rash, and joint involvement.

Laboratory Tests

Several laboratory tests are commonly used to support the diagnosis of AOSD:

• Complete Blood Count (CBC): A CBC can reveal elevated white blood cell count (leukocytosis), particularly neutrophils, and increased platelet count.


• Acute Phase Reactants: Blood tests measuring acute phase reactants such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are often elevated in AOSD patients, indicating ongoing inflammation.


• Liver Function Tests: AOSD can affect the liver, so liver function tests may show elevated liver enzymes.


• Ferritin: Ferritin levels are typically significantly elevated in AOSD patients and can serve as a useful marker for disease activity.

Exclusion of Other Conditions

Since the symptoms of AOSD can overlap with other diseases, it is crucial to exclude other potential causes before confirming the diagnosis. Some conditions that need to be ruled out include:

• Infections: Certain infections, such as viral or bacterial infections, can present with similar symptoms. Appropriate tests, such as blood cultures or serological tests, may be performed to exclude infectious causes.


• Rheumatologic Conditions: Other rheumatologic diseases, such as rheumatoid arthritis or systemic lupus erythematosus, may have overlapping symptoms. Clinical evaluation, specific laboratory tests, and imaging studies can help differentiate AOSD from these conditions.


• Malignancies: In rare cases, certain cancers can present with symptoms resembling AOSD. Imaging studies, biopsies, or other specific tests may be necessary to rule out malignancies.

Additional Diagnostic Tools

While there is no specific test to definitively diagnose AOSD, additional tools may aid in the diagnosis:

• Imaging: X-rays, ultrasound, or magnetic resonance imaging (MRI) may be used to assess joint involvement, rule out other causes of joint pain, or detect complications such as joint destruction.


• Joint Aspiration: In some cases, joint aspiration may be performed to analyze synovial fluid for signs of inflammation or infection.


• Biopsy: In rare instances, a biopsy of affected tissues (such as skin or lymph nodes) may be recommended to exclude other conditions and confirm the diagnosis.

Consultation with Rheumatologist

Given the complexity of diagnosing AOSD, it is often beneficial to involve a rheumatologist, a specialist in autoimmune and inflammatory diseases. Rheumatologists have expertise in recognizing and managing AOSD and can provide valuable insights into the diagnostic process.

Conclusion

Diagnosing Adult-onset Still's Disease requires a comprehensive approach involving clinical evaluation, laboratory tests, exclusion of other conditions, and sometimes additional diagnostic tools. The combination of characteristic symptoms, elevated acute phase reactants, and exclusion of other potential causes can help confirm the diagnosis. Consulting with a rheumatologist can further enhance the accuracy of the diagnosis and ensure appropriate management of the disease.