Still’s disease is a rare, body-wide inflammatory condition. It includes two related disorders: Systemic Juvenile Idiopathic Arthritis (SJIA) in children, and Adult-Onset Still’s Disease (AOSD), which emerges between ages 16 and 35. While some individuals experience a single episode that resolves, for others it can become a chronic condition with recurring flare-ups. The underlying cause remains unknown.
Core Symptoms and Presentation
The classic presentation of Still’s disease involves a distinct trio of symptoms. A high, spiking fever is a hallmark, often exceeding 102°F (39°C). This fever follows a predictable daily pattern, peaking once or twice a day, often in the late afternoon or evening, before returning to normal. Many people also experience significant muscle pain that intensifies with the fever spikes.
Accompanying the fever is a characteristic skin rash. This rash is a faint, salmon-pink color and is non-itchy. It often appears on the trunk, arms, or legs and emerges during febrile episodes, only to fade as body temperature subsides.
Joint pain, or arthritis, is the third component of the classic triad. Joints can become swollen, stiff, and painful, with the wrists being particularly susceptible to inflammation that can lead to long-term damage if not controlled. Beyond these core symptoms, individuals may also experience a severe sore throat, swollen lymph nodes, and feelings of fatigue and malaise.
The Diagnostic Process
There is no single test to confirm Still’s disease, so it is diagnosed by exclusion. This means physicians must rule out other conditions with similar symptoms, such as infections, cancers like lymphoma, and other autoimmune disorders. The process requires evaluating symptoms and using laboratory tests to build a case for the diagnosis.
Blood tests are a central part of this evaluation. Doctors look for markers of widespread inflammation, including a high white blood cell count (leukocytosis). Other indicators are an elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). A telling marker for Still’s disease is an extremely high level of ferritin, a protein that stores iron, which is often disproportionately elevated.
To provide a structured approach, clinicians use established criteria, such as the Yamaguchi criteria for Adult-Onset Still’s Disease. These criteria organize clinical findings like the characteristic fever, rash, and arthritis, along with laboratory results. This framework requires meeting several major and minor criteria while also excluding other diseases before confirming a diagnosis.
Treatment Approaches
The primary goals of treatment are to control systemic inflammation, alleviate symptoms, and prevent irreversible joint damage. The strategy is layered, starting with initial therapies and escalating to more targeted medications if the disease is severe or persistent. Each approach is tailored to the individual’s symptoms and disease course.
First-line treatments include nonsteroidal anti-inflammatory drugs (NSAIDs), like ibuprofen or naproxen, to manage milder symptoms. For more significant inflammation, corticosteroids like prednisone are often necessary. These drugs are effective for controlling fever, rash, and joint swelling, but their long-term use is managed carefully due to potential side effects.
If symptoms are not controlled or the disease becomes chronic, doctors introduce other medications. Disease-Modifying Antirheumatic Drugs (DMARDs), such as methotrexate, may be used to suppress the overactive immune system. For persistent cases, biologic agents offer a targeted approach. These medications block specific inflammatory proteins, like interleukin-1 (IL-1) and interleukin-6 (IL-6), which are drivers of inflammation in Still’s disease.
Potential Complications
While many people manage their condition effectively, there are potential long-term complications. The persistent inflammation can lead to chronic destructive arthritis, causing lasting damage to the affected joints, particularly the wrists. In some cases, inflammation can also affect internal organs like the heart or lungs, though this is less common.
The most serious complication of Still’s disease is a life-threatening condition known as Macrophage Activation Syndrome (MAS). MAS is a form of secondary hemophagocytic lymphohistiocytosis (HLH) that occurs when the immune system becomes dangerously overactive. This immune storm leads to a rapid, severe inflammatory response throughout the body.
Warning signs of MAS include a sudden persistent high fever, an abrupt drop in blood cell counts, and signs of liver dysfunction. Patients may also exhibit neurological symptoms and an enlarged spleen. Because MAS can progress rapidly and be fatal, it is a medical emergency requiring immediate and aggressive immunosuppressive therapy.