Juvenile Idiopathic Arthritis (JIA): Diagnosis, Treatment, and Related Conditions

Posted on May 7, 2024 in Medicine & Health

Examination of a Child with Rheumatic Diseases

I. Medical History

• Pain (7 Questions)
• Predisposing Factors
• Trauma
• Fever/Rashes
• Weight Loss
• Abdominal Pain
• Eye Damage

II. Physical Exam

• Blood Pressure
• Skin
• Eyes

III. Lab Tests

IV. Radiology (X-ray/Ultrasound)

Diagnosis Criteria for JIA

• Duration of 6 weeks

Subtypes:

1. Systemic
2. Oligoarthritis (Persistent/Extended)
3. Polyarthritis (RF factor negative)
4. Polyarthritis (RF factor positive)
5. Psoriatic Arthritis

RF Factors:

• Oligo: HLA DR5+8
• AS: HLA B27
• Poly: HLA DR4

JIA Treatment

Goals:

• Reduce Inflammation
• Prevent Deformity
• Prevent Blindness

Reactive Arthritis

General Characteristics:

• 8-14 years old
• Girls = Boys

Causes:

• Salmonella enteritidis
• Salmonella typhimurium
• Shigella flexneri
• Shigella dysenteriae
• Campylobacter jejuni
• Yersinia enterocolitica
• Streptococcus sp.

Clinical Features:

• Onset 1-3 weeks after disease…lasts 1-2 weeks….
• Large Joints (Oligo, Mono = 70% Mostly Leg)
• Uncommon: Fluid retention in joint
• X-ray: Nothing!
• Triad = Ocular inflammation/Urethritis/Arthritis!

Treatment:

• NSAIDs for 6 weeks (after infection)
• Antibiotics if additional infection

Systemic Disorders of Connective Tissue

Autoimmune diseases with abnormal humoral and cell-mediated immune responses, leading to inflammation.

Causes of Immune Dysregulation:

• Infection
• Medication
• Other Antigens
• Genetic Factors

Possible Damage:

• Skin
• Nails
• Mucous membranes
• Joints
• Lymph nodes
• Muscles
• Parenchymal organs
• Serous membranes
• Eyes
• Central nervous system

Systemic Lupus Erythematosus (SLE)

General Characteristics:

• 20% of patients become sick before 20 years old
• Usually teenage girls

Peculiarities in Children:

• High Activity
• Aggressive
• Systemic
• Needs Emergency Treatment!

Clinical Features:

• General: Fatigue, anorexia, weight loss, lymphadenopathy
• Musculoskeletal: Arthralgia, arthritis
• Skin: Butterfly rash on face
• Renal: Glomerulonephritis, hypertension, nephrotic syndrome, renal failure
• Hematopoietic: Hemolytic anemia, thrombocytopenia
• Lab: High ESR+CRP, Low C3&C4, ANA (+), Anti-dsDNA Ab

Treatment:

• Must be very aggressive
• High dose of glucocorticoids IV + pulse therapy!
• Later, put patients on disease-modifying therapy depending on which system is more affected!

Dermatomyositis

Disease of the skin and striated muscle. Non-purulent and non-infectious inflammation of striated muscle with skin involvement.

Diagnostic Criteria:

1. Symmetric progressive muscle weakness
2. EMG will show characteristics of myositis!
3. Enzyme elevation in blood serum
4. Muscle biopsy shows chronic inflammation
5. Rash (very typical)

Clinical Features:

1. Rash (100%) Gottron’s papules
2. Weakness (100%)
3. Myalgia (65%)
4. Fever (44%)
5. Periorbital edema
6. Gottron’s papules/Rash

Treatment:

• Start with glucocorticoids, then methotrexate

Scleroderma

Disease only in the skin (localized). Focus on localized scleroderma, more common in children.

Clinical Features:

1. Subtypes depend on how it looks on the skin:
   • Subtype 1: Morphea (circles)
   • Subtype 2: Linear (subcutaneous down to leg)
   • Subtype 3: Coup de sabre (only in face) goes with neurological symptoms (Parry Romberg Syndrome)
2. No systemic changes
3. Autoantibodies (ANA+) + fibrosis of skin
4. Stages: Redness/swelling/induration/atrophy

Treatment:

Topical with emollients only!!

Henoch-Schonlein Purpura (Small Non-ANCA Vasculitis)

General Characteristics:

• Most often diagnosed in children (90%)
• Peak in autumn and spring
• Palpable rash (100%)
• Kidney/Arthritis/GI bleeding
• Upper respiratory tract infection before in 50%
• IgA elevated

Clinical Features:

• Palpable purpura in 100% of cases + (arthritis/nephritis/GI bleeding)
• All rash in legs, rarely in upper body

Pathophysiology:

IgA deposits in blood vessels

Differential Diagnosis:

Diseases that mimic this rash:

• A- Thrombocytopenia ——-> CBC
• B- Meningococcal Sepsis (Fever) ——–> All clinical features, FEVER + General Condition (meningococcal has fever, bad condition)

Treatment:

• A- With antihistamines + anti-allergic diet
• B- If arthritis: Analgesics + NSAIDs
• If nephrotic symptoms/GI bleeding: A + glucocorticoids

Kawasaki Disease (Medium-Sized Vasculitis)

General Characteristics:

1. More common in Asia
2. Age is around <5 years old or before
3. Fever lasting 5 days (like normal infection) + CRASH:
   1. Conjunctivitis
   2. Rash
   3. Adenopathy
   4. Strawberry tongue
   5. Hand/Foot changes
4. Increase in ESR, CRP, thrombocytes
5. This disease affects coronary arteries, which causes aneurysms.

Diagnosis:

Need to have 5/6 criteria:

1. Fever lasting at least 5 days
2. Bilateral non-purulent conjunctival injection
3. Polymorphic rash at the beginning of fever
4. Changes in mucosa of oropharynx:
   • Redness/dry/lip angel tear
5. Changes in peripheral extremities
6. Acute non-purulent lymph node adenitis up to 1.5 cm

——–> Diagnosis = 5 out of 6!

Treatment:

Immunoglobulin (IV) 2 g/kg + high dose of aspirin 80-100 mg/kg/day

—> Do US echo of heart to check for aneurysms

Rheumatic Fever

Secondary disease after tonsillitis (B-hemolytic Streptococcus). Most often affects children from 5-18 years old. Streptococcal antigen reacts with human tissue. Genetic predisposition is a must (HLA DR4, HLA2, DR).

Jones Criteria:

Proof of streptococcal infection +

Treatment:

1. Penicillin for 14 days
2. Give aspirin/NSAIDs

Rheumatic Fever Prophylaxis

1. First proper treatment
2. Anti-inflammation (aspirin 100mg/kg)
3. (prednisolone 2-2.5 mg/kg)
4. Treat complications (heart failure)
5. Valvuloplasty
6. If rheumatic carditis + heart defect —> 10+ years of prophylaxis
7. Rheumatic carditis without defect —> 10 years
8. Acute rheumatic fever —> 5 years