Immunology · Year 2 · from Immunology
Case 1: Systemic Lupus Erythematosus
Patient Demographics
- Age: 28 years old
- Sex: Female
- Ethnicity: African American
Chief Complaint
Joint pain, facial rash, and fatigue for 3 months
History of Present Illness
A 28-year-old woman presents with a 3-month history of progressive fatigue, joint pain, and a rash on her face. She describes morning stiffness lasting over an hour and symmetric pain in her hands, wrists, and knees without significant swelling. The facial rash appeared after sun exposure during a beach vacation and has persisted. She also reports hair loss, oral ulcers, and occasional low-grade fevers. Recently, she noticed swelling in her legs and foamy urine.
Past Medical History
- Recurrent episodes of pleuritic chest pain over past year
- History of photosensitivity
- One miscarriage at 12 weeks gestation
Family History
- Mother with rheumatoid arthritis
- Maternal aunt with Sjogren's syndrome
Physical Examination
- General: Fatigued-appearing woman in no acute distress
- Vital Signs: T 37.8C, HR 92, RR 16, BP 148/94
- Skin: Erythematous malar rash sparing nasolabial folds; diffuse alopecia; oral ulcers on hard palate
- Musculoskeletal: Tenderness at MCPs, wrists, and knees bilaterally without synovitis
- Cardiovascular: Normal S1/S2, no murmurs or rubs
- Pulmonary: Decreased breath sounds at left base
- Extremities: 2+ pitting edema to mid-calf bilaterally
Laboratory Workup
| Test | Result | Reference Range |
|---|---|---|
| WBC | 3,100/uL | 4,500-11,000/uL |
| Hemoglobin | 10.2 g/dL | 12-16 g/dL |
| Platelets | 98,000/uL | 150,000-400,000/uL |
| Creatinine | 1.4 mg/dL | 0.6-1.2 mg/dL |
| ANA | 1:640 homogeneous | Negative |
| Anti-dsDNA | Positive (high titer) | Negative |
| Anti-Smith | Positive | Negative |
| Complement C3 | 45 mg/dL (low) | 90-180 mg/dL |
| Complement C4 | 8 mg/dL (low) | 10-40 mg/dL |
| Urinalysis | 3+ protein, 2+ blood, RBC casts | Normal |
| 24-hour urine protein | 3.2 g | <150 mg |
| Chest X-ray | Small left pleural effusion | Normal |
Clinical Image
Image showing characteristic malar (butterfly) rash distribution pattern seen in systemic lupus erythematosus, typically sparing the nasolabial folds. Image source: Course lecture materials.
Diagnosis
Systemic Lupus Erythematosus (SLE) with Class IV Lupus Nephritis
Discussion
SLE is a prototypical systemic autoimmune disease characterized by autoantibodies against nuclear antigens and multi-organ involvement:
Pathogenesis:
- Defective clearance of apoptotic cells exposes nuclear antigens
- Loss of tolerance leads to autoantibody production (ANA, anti-dsDNA, anti-Smith)
- Immune complex deposition causes inflammation via complement activation
- Type I interferon signature amplifies the autoimmune response
This patient meets multiple classification criteria:
- Malar rash (photosensitive)
- Arthritis (non-erosive)
- Serositis (pleuritis)
- Renal involvement (nephritis with proteinuria and casts)
- Hematologic (leukopenia, anemia, thrombocytopenia)
- ANA positive
- Anti-dsDNA and anti-Smith positive
Autoantibodies in SLE and their associations:
| Autoantibody | Association |
|---|---|
| Anti-dsDNA | Lupus nephritis, disease activity |
| Anti-Smith | Most specific for SLE |
| Anti-Ro (SS-A) | Neonatal lupus, photosensitivity |
| Anti-La (SS-B) | Sjogren's overlap |
| Antiphospholipid | Thrombosis, pregnancy loss |
Low complement levels indicate active immune complex disease.
Treatment
- Immediate: Renal biopsy to classify nephritis
- Induction therapy: Mycophenolate mofetil or cyclophosphamide plus corticosteroids for Class IV nephritis
- Maintenance: Mycophenolate mofetil with low-dose prednisone
- Hydroxychloroquine: All SLE patients (reduces flares, thrombosis, damage accrual)
- Sun protection: Strict photoprotection
- Monitoring: Anti-dsDNA titers and complement levels correlate with disease activity