What are the symptoms of Still's disease?

Symptoms of Still's Disease

Still's disease presents with four cardinal features: high spiking fevers ≥39°C (102.2°F) lasting at least 7 days, a transient salmon-pink rash that coincides with fever spikes, musculoskeletal pain (arthralgia or myalgia), and markedly elevated inflammatory markers—critically, overt arthritis is NOT required for diagnosis and typically appears later. 1, 2

Core Clinical Manifestations

Fever Pattern

• High spiking fevers exceeding 39°C (102.2°F) occur in approximately 96% of patients 3
• The fever follows a characteristic quotidian (once daily) or double-quotidian (twice daily) spiking pattern 1, 2
• Fever episodes are transient, with temperature returning to normal or near-normal between spikes 3
• This distinctive fever pattern must persist for at least 7 days to meet diagnostic criteria 1, 2

Skin Manifestations

• The evanescent salmon-pink (erythematous) rash occurs in 51-87% of patients 3
• The rash is transient and characteristically coincides with fever spikes 1, 2
• It predominantly affects the trunk and proximal limbs 3
• The rash may be mildly pruritic and can be challenging to identify on darker skin 1
• Critical pitfall: Do not dismiss this rash as a drug allergy—it is pathognomonic for Still's disease 3

Musculoskeletal Involvement

• Arthralgia or myalgia is present in 64-100% of patients and is sufficient for diagnosis 1, 3
• Overt arthritis is NOT mandatory for diagnosis and typically appears later with a median delay of 1 month after disease onset (range 0 to several months) 1, 2
• When arthritis develops, it most commonly affects the knees, wrists, and ankles in a symmetric polyarthritis pattern 3
• Critical pitfall: Requiring arthritis for diagnosis leads to dangerous and potentially life-threatening diagnostic delays 1

Additional Common Symptoms

Systemic Features

• Sore throat occurs frequently, particularly in younger patients 4, 5
• Lymphadenopathy and/or splenomegaly are common systemic manifestations 5
• Hepatomegaly occurs in 50-75% of patients 3
• Critical pitfall: Do not attribute liver dysfunction solely to NSAIDs—hepatomegaly and abnormal liver biochemistry are intrinsic disease features 3

Serosal Involvement

• Pericarditis can develop and may progress to cardiac tamponade 3
• Pleuritis occurs, particularly in patients with high disease activity 3, 6
• Routine transthoracic echocardiography or thoracic ultrasonography at diagnosis can help detect serosal involvement early 7

Laboratory Abnormalities (Part of Disease Presentation)

Inflammatory Markers

• Neutrophilic leukocytosis is typical, with 50% of patients having white blood cell counts >15×10⁹ cells/L and 37% having counts >20×10⁹ cells/L 3
• Erythrocyte sedimentation rate (ESR) is elevated in virtually all patients 3
• C-reactive protein (CRP) is typically markedly raised 1, 3

Ferritin Elevation

• Very high ferritin levels are characteristic, ranging from 4,000-30,000 ng/mL (approximately 5-fold or more above the upper normal limit) 2, 3
• Extreme ferritin levels up to 250,000 ng/mL have been reported 3
• Ferritin levels correlate with disease activity 3

Other Laboratory Features

• Anemia of chronic disease is common with active disease and normalizes with remission 3
• Platelet count is often increased 1
• Fibrinogen and D-dimers are typically elevated 1

Life-Threatening Complications (Critical to Recognize)

Macrophage Activation Syndrome (MAS)

• MAS occurs in up to 23% of patients with Still's disease and carries high mortality 3, 8, 5
• MAS can develop at disease onset, during treatment, or even during remission—particularly when concurrent infection is present 2, 3
• Key clinical features of MAS include:
  • Persistent high fever with loss of the characteristic quotidian pattern 9
  • Pancytopenia (declining platelet counts even within normal ranges may signal early MAS) 7
  • Elevated liver enzymes 9
  • Paradoxically, ferritin may be very high (often >10,000 ng/mL) but can decrease in established MAS 9, 10
• Critical pitfall: Do not miss pancytopenia—it signals potentially fatal MAS requiring urgent intervention 3

Other Severe Complications

• Disseminated intravascular coagulation can occur, particularly in older patients 4
• Parenchymal lung involvement ("Still's lung disease") may develop 9
• Cardiac tamponade from pericarditis 3
• Respiratory failure 3
• Amyloidosis in chronic cases 3

Disease Patterns and Heterogeneity

Clinical Phenotypes

• Three distinct clinical patterns exist, each affecting approximately one-third of patients 3:
  • Self-limited/monocyclic pattern: Single systemic episode with favorable prognosis
  • Intermittent/polycyclic systemic pattern: Multiple flares alternating with remissions
  • Chronic articular pattern: Persistently active disease dominated by articular manifestations that can lead to joint destruction

Age-Related Variations

• Older-onset Still's disease (age >60 years) presents with less-typical features 4
• Older patients have less frequent sore throat, skin lesions, and splenomegaly 4
• Older patients experience more complications including pleuritis and disseminated intravascular coagulation 4
• Higher inflammatory marker levels and poorer outcomes occur in older patients 4

Radiographic Features (When Arthritis Develops)

• Bilateral intercarpal and carpometacarpal joint space narrowing occurs in 69% of patients with chronic arthritis 3
• Pericapitate ankylosis develops in 25% of cases 3
• Critical pitfall: Do not overlook wrist involvement—carpal and pericapitate abnormalities distinguish Still's disease from rheumatoid arthritis 3