# Clinical Cases: Rheumatic Diseases

## Case 1: Rheumatoid Arthritis

### Patient Presentation
A 42-year-old woman presents with 3 months of bilateral hand pain, stiffness, and swelling. She reports that her fingers feel stiff in the morning for approximately 2 hours before loosening up. The pain and stiffness are worse in the morning and after periods of inactivity. She has noticed difficulty opening jars and has been dropping things more frequently.

### Vital Signs
- Blood Pressure: 122/74 mmHg
- Heart Rate: 76 bpm
- Temperature: 37.0°C

### Physical Examination
- General: Well-appearing
- Hands: Symmetric swelling and tenderness of MCP and PIP joints bilaterally, warmth over affected joints, no DIP involvement
- Wrists: Bilateral synovitis
- Feet: Tenderness at MTP joints bilaterally
- No nodules, no rashes

### Laboratory Results
- **RF (Rheumatoid Factor)**: 85 IU/mL (positive, normal <14)
- **Anti-CCP antibodies**: 124 U/mL (positive, normal <20)
- **ESR**: 48 mm/hr
- **CRP**: 2.8 mg/dL
- **CBC**: Normal
- **CMP**: Normal
- **Hand X-rays**: Periarticular osteopenia, soft tissue swelling, no erosions yet

### Clinical Image
![RA Hands](image_01.png)
*Figure 1: Clinical photograph of hands demonstrating symmetric swelling of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints characteristic of rheumatoid arthritis.*

**Image Source**: Educational illustration for teaching purposes.

### Questions

1. **What classification criteria support the diagnosis of rheumatoid arthritis?**
   - A) Presence of joint pain only
   - B) 2010 ACR/EULAR criteria: joint involvement, serology (RF/anti-CCP), acute phase reactants, symptom duration >6 weeks
   - C) Positive ANA only
   - D) Erosions on X-ray required for diagnosis

2. **What is the significance of anti-CCP antibodies?**
   - A) Non-specific inflammatory marker
   - B) Highly specific for RA (>95%), associated with erosive disease and worse prognosis
   - C) Rules out RA when negative
   - D) Indicates infection

3. **What is the first-line DMARD for rheumatoid arthritis?**
   - A) Prednisone
   - B) Methotrexate
   - C) NSAIDs
   - D) Biologic agents

4. **What monitoring is required for methotrexate therapy?**

5. **When should biologic DMARDs be considered?**

### Answers

1. **B) 2010 ACR/EULAR criteria: joint involvement, serology (RF/anti-CCP), acute phase reactants, symptom duration >6 weeks** - Classification criteria (score ≥6/10):
   - Joint involvement (0-5 points): Number and size of involved joints
   - Serology (0-3 points): RF and anti-CCP negative, low positive, or high positive
   - Acute phase reactants (0-1 point): Normal or abnormal CRP/ESR
   - Duration (0-1 point): <6 weeks or ≥6 weeks

2. **B) Highly specific for RA (>95%), associated with erosive disease and worse prognosis** - Anti-CCP significance:
   - Specificity >95% for RA
   - Can be positive years before symptom onset
   - Associated with more aggressive, erosive disease
   - RF is less specific (also elevated in infections, other autoimmune diseases, healthy elderly)
   - Double-positive (RF+ and anti-CCP+) indicates highest risk

3. **B) Methotrexate** - Treatment approach:
   - Methotrexate is first-line DMARD (disease-modifying antirheumatic drug)
   - Start 10-15 mg weekly, titrate to 25 mg weekly
   - Add folic acid 1 mg daily to reduce side effects
   - Bridge with low-dose prednisone (≤10 mg/day) while DMARD takes effect
   - NSAIDs for symptomatic relief but do not modify disease

4. **Methotrexate monitoring**:
   - **Baseline**: CBC, CMP (liver, kidney function), hepatitis B/C serologies, chest X-ray
   - **Ongoing**: CBC, CMP every 2-4 weeks initially, then every 8-12 weeks when stable
   - **Watch for**: Hepatotoxicity (elevated LFTs), bone marrow suppression (cytopenias), pulmonary toxicity (pneumonitis)
   - **Contraindications**: Pregnancy (teratogenic), significant liver disease, significant renal impairment
   - Avoid alcohol; supplement with folic acid

5. **Indications for biologic DMARDs**:
   - Inadequate response to methotrexate (after 3-6 months at optimal dose)
   - Intolerance to methotrexate
   - High disease activity with poor prognostic factors (high anti-CCP, erosions, functional impairment)
   - Options: TNF inhibitors (etanercept, adalimumab, infliximab), IL-6 inhibitors (tocilizumab), JAK inhibitors (tofacitinib), B-cell depleting (rituximab), T-cell costimulation blocker (abatacept)

---

## Case 2: Systemic Lupus Erythematosus

### Patient Presentation
A 28-year-old woman presents with 2 months of fatigue, joint pain, and a facial rash. She has noticed the rash worsens with sun exposure. She reports diffuse hair thinning and painful mouth ulcers. She also describes episodes where her fingers turn white then blue in cold weather.

### Vital Signs
- Blood Pressure: 138/88 mmHg
- Heart Rate: 84 bpm
- Temperature: 37.6°C

### Physical Examination
- General: Fatigued appearance
- Skin: Erythematous malar rash sparing nasolabial folds, oral ulcers on hard palate, diffuse non-scarring alopecia
- Joints: Symmetric polyarthralgia without obvious synovitis (Jaccoud's arthropathy pattern)
- Cardiovascular: Normal
- Lungs: Clear

### Laboratory Results
- **ANA**: 1:640 (positive, homogeneous pattern)
- **Anti-dsDNA**: 120 IU/mL (positive)
- **Anti-Smith antibodies**: Positive
- **C3**: 58 mg/dL (low, normal 90-180)
- **C4**: 8 mg/dL (low, normal 10-40)
- **CBC**: WBC 3,200/μL, Hgb 10.8 g/dL, Platelets 118,000/μL
- **Urinalysis**: Protein 2+, 10-15 RBC/hpf, RBC casts
- **Creatinine**: 1.2 mg/dL
- **Spot urine protein/creatinine ratio**: 1.8 g/g

### Clinical Image
![Malar Rash SLE](image_02.png)
*Figure 2: Classic malar (butterfly) rash of systemic lupus erythematosus - erythematous rash over cheeks and bridge of nose characteristically sparing the nasolabial folds.*

**Image Source**: Educational illustration for teaching purposes.

### Questions

1. **What clinical and laboratory features support the diagnosis of SLE?**
   - A) Positive ANA alone
   - B) Multiple criteria: malar rash, oral ulcers, arthritis, renal involvement, hematologic abnormalities, positive ANA, anti-dsDNA, low complements
   - C) Joint pain only
   - D) Fatigue and fever

2. **What antibodies are most specific for SLE?**
   - A) ANA
   - B) Anti-dsDNA and anti-Smith antibodies
   - C) Rheumatoid factor
   - D) Anti-CCP

3. **What findings suggest lupus nephritis in this patient?**
   - A) Elevated creatinine only
   - B) Proteinuria, hematuria with RBC casts, low complements, elevated anti-dsDNA
   - C) Positive ANA
   - D) Hypertension alone

4. **What is the next step in management for suspected lupus nephritis?**

5. **What are the treatment principles for SLE?**

### Answers

1. **B) Multiple criteria: malar rash, oral ulcers, arthritis, renal involvement, hematologic abnormalities, positive ANA, anti-dsDNA, low complements** - SLICC or ACR/EULAR criteria include:
   - Mucocutaneous: Malar rash, discoid rash, photosensitivity, oral ulcers, alopecia
   - Musculoskeletal: Arthritis
   - Renal: Proteinuria, RBC casts
   - Hematologic: Hemolytic anemia, leukopenia, lymphopenia, thrombocytopenia
   - Immunologic: ANA, anti-dsDNA, anti-Smith, low complements, antiphospholipid antibodies

2. **B) Anti-dsDNA and anti-Smith antibodies** - Antibody significance:
   - ANA: Sensitive (>95%) but not specific
   - Anti-dsDNA: Highly specific; correlates with disease activity and nephritis
   - Anti-Smith: Most specific (>99%) but less sensitive
   - Low complements (C3, C4): Indicate active immune complex consumption

3. **B) Proteinuria, hematuria with RBC casts, low complements, elevated anti-dsDNA** - Lupus nephritis indicators:
   - Proteinuria (>500 mg/24h)
   - Active urinary sediment (RBC casts = glomerulonephritis)
   - Elevated creatinine
   - Elevated anti-dsDNA (correlates with renal activity)
   - Low complements (active disease)
   - This patient has multiple concerning features

4. **Next step for suspected lupus nephritis**:
   - **Renal biopsy** is essential for:
     - Confirming diagnosis
     - Classifying nephritis (Class I-VI)
     - Guiding treatment intensity
   - Treatment depends on class:
     - Class I-II: May need only hydroxychloroquine and ACE inhibitor
     - Class III-IV: Requires immunosuppression (mycophenolate or cyclophosphamide + steroids)
     - Class V (membranous): Immunosuppression if nephrotic-range proteinuria
   - Also start ACE inhibitor for renal protection

5. **Treatment principles for SLE**:
   - **Hydroxychloroquine**: All SLE patients (reduces flares, mortality, damage)
   - **NSAIDs/low-dose steroids**: For mild symptoms (arthritis, serositis)
   - **Immunosuppressants**: For major organ involvement
     - Mycophenolate mofetil (preferred for nephritis induction and maintenance)
     - Azathioprine (maintenance therapy)
     - Cyclophosphamide (severe nephritis, neuropsychiatric lupus)
   - **Belimumab**: B-cell targeted biologic for active SLE
   - **Avoid sun exposure**: Photosensitivity triggers flares
   - **Monitoring**: Regular labs for disease activity and medication toxicity

---

## Case 3: Gout

### Patient Presentation
A 54-year-old man presents with acute onset of severe left first metatarsophalangeal (MTP) joint pain that woke him from sleep 12 hours ago. The pain is so intense he cannot bear weight or tolerate even bedsheet contact. He had a similar episode 6 months ago that resolved spontaneously. He has a history of hypertension treated with hydrochlorothiazide and reports drinking 2-3 beers most nights.

### Vital Signs
- Blood Pressure: 148/92 mmHg
- Heart Rate: 88 bpm
- Temperature: 37.8°C

### Physical Examination
- General: In significant pain
- Left foot: First MTP joint is exquisitely tender, swollen, erythematous, and warm; overlying skin is shiny and taut
- Right foot: Normal
- Hands: No tophi
- Ears: No tophi

### Laboratory Results
- **Serum uric acid**: 9.8 mg/dL (elevated, normal <6.8)
- **WBC**: 12,400/μL
- **Creatinine**: 1.3 mg/dL
- **Joint aspiration**: Cloudy fluid, WBC 42,000/μL (predominantly neutrophils), negatively birefringent needle-shaped crystals

### Clinical Image
![Gout Podagra](image_03.png)
*Figure 3: Acute gouty arthritis of the first metatarsophalangeal joint (podagra) showing intense erythema, swelling, and characteristic taut, shiny overlying skin.*

**Image Source**: Educational illustration for teaching purposes.

### Questions

1. **What finding on joint aspiration confirms the diagnosis of gout?**
   - A) Elevated WBC count
   - B) Negatively birefringent needle-shaped monosodium urate crystals
   - C) Positive culture
   - D) Low glucose

2. **What is the appropriate acute treatment for this gout flare?**
   - A) Allopurinol
   - B) NSAIDs, colchicine, or corticosteroids (but NOT urate-lowering therapy acutely)
   - C) Probenecid
   - D) Increased hydration only

3. **What risk factors for gout does this patient have?**
   - A) Young age
   - B) Thiazide diuretic use, alcohol consumption, elevated uric acid, male sex
   - C) Vegetarian diet
   - D) Low BMI

4. **When should urate-lowering therapy be initiated?**

5. **What is the target serum uric acid level for gout management?**

### Answers

1. **B) Negatively birefringent needle-shaped monosodium urate crystals** - Definitive diagnosis:
   - Joint aspiration is gold standard
   - MSU crystals are needle-shaped and show negative birefringence (yellow when parallel to polarizer axis)
   - Pseudogout (CPPD) crystals are rhomboid and show positive birefringence (blue when parallel)
   - High WBC suggests inflammatory arthritis but is not specific
   - Always rule out septic arthritis if clinically suspected

2. **B) NSAIDs, colchicine, or corticosteroids (but NOT urate-lowering therapy acutely)** - Acute treatment:
   - **NSAIDs**: Indomethacin 50 mg TID or naproxen 500 mg BID (avoid if CKD, GI risk, or cardiovascular disease)
   - **Colchicine**: 1.2 mg initially, then 0.6 mg 1 hour later; then 0.6 mg daily-BID (best if started within 12-24 hours)
   - **Corticosteroids**: Prednisone 30-40 mg/day tapered over 7-10 days OR intra-articular injection
   - Do NOT start allopurinol during acute flare (can prolong/worsen flare)

3. **B) Thiazide diuretic use, alcohol consumption, elevated uric acid, male sex** - Risk factors:
   - Thiazides decrease uric acid excretion
   - Alcohol (especially beer) increases uric acid production and decreases excretion
   - Male sex (premenopausal women protected by estrogen)
   - Obesity, metabolic syndrome
   - Chronic kidney disease
   - Diet high in purines (organ meats, shellfish)
   - Certain medications (cyclosporine, low-dose aspirin)

4. **When to initiate urate-lowering therapy**:
   - ≥2 flares per year
   - Presence of tophi
   - Radiographic evidence of gouty erosions
   - Chronic kidney disease (stage ≥2)
   - History of urolithiasis
   - Consider for any patient after first flare if comorbidities present
   - Wait until acute flare resolves (or at least 2 weeks) before starting
   - Provide flare prophylaxis (colchicine 0.6 mg daily-BID) for 3-6 months when starting

5. **Target serum uric acid**:
   - Goal: <6.0 mg/dL (below saturation point of 6.8 mg/dL)
   - More stringent goal <5.0 mg/dL for severe/tophaceous gout
   - **Allopurinol**: First-line; start low (100 mg), titrate to goal
   - **Febuxostat**: Alternative xanthine oxidase inhibitor
   - **Probenecid**: Uricosuric agent; avoid if CKD or nephrolithiasis
   - Treat-to-target approach with regular uric acid monitoring

---

## Learning Points

1. **Rheumatoid arthritis** is a symmetric inflammatory polyarthritis affecting MCP/PIP joints; anti-CCP is highly specific; methotrexate is first-line DMARD.

2. **Systemic lupus erythematosus** is a multisystem autoimmune disease; anti-dsDNA and anti-Smith are specific; hydroxychloroquine is foundational therapy; lupus nephritis requires renal biopsy.

3. **Gout** is diagnosed by negatively birefringent needle-shaped MSU crystals; treat acute flares with NSAIDs/colchicine/steroids; urate-lowering therapy targets uric acid <6.0 mg/dL.

4. **Joint aspiration** is essential when crystal arthropathy or septic arthritis is suspected.

5. **Early and aggressive treatment** of inflammatory arthritis prevents joint damage and disability.