Systemic Sclerosis (Scleroderma): Pathological Essentials
Systemic Sclerosis is a multisystem autoimmune disorder defined by three pathological pillars: autoimmune-mediated vascular damage, persistent activation of fibroblasts, and excessive collagen deposition in the skin and internal organs.
1. Classification and Serological Markers
| Variant | Antibody | Clinical Scope |
|---|---|---|
| Diffuse | Anti-Scl-70 | Widespread skin involvement + rapid progression to visceral organ fibrosis. |
| Limited | Anti-Centromere | Skin involvement is limited to the hands/face. Known as CREST syndrome. |
2. Clinical Manifestations
- CREST Syndrome (Limited Variant):
- C – Calcinosis cutis
- R – Raynaud phenomenon (the hallmark, earliest sign)
- E – Esophageal dysmotility (reflux, dysphagia)
- S – Sclerodactyly (thickening of finger skin)
- T – Telangiectasia (dilated blood vessels)
- Visceral Involvement:
- Renal: Scleroderma renal crisis—characterized by sudden-onset malignant hypertension, requiring prompt ACE inhibitor therapy.
- Pulmonary: Interstitial lung disease and pulmonary arterial hypertension are major causes of death.
- Gastrointestinal: Fibrosis leading to “pouch-like” colonic sacculations and impaired peristalsis.
3. Pathological Exam Must-Knows
Pathology Pearl: The disease starts with microvascular endothelial injury, which triggers chronic platelet activation and recruitment of inflammatory cells. These cells release cytokines (e.g., TGF-beta, PDGF) that stimulate fibroblasts to synthesize excessive, disorganized extracellular matrix, transforming normal tissue into dense, fibrotic scar-like tissue.
- Raynaud Phenomenon: Ischemic blanching of digits followed by cyanosis and reactive hyperemia (redness). It can occur alone or precede clinical sclerosis by years.
- Skin Biopsy: Shows thinning of the epidermis and a thick, dense zone of dermal collagen replacing normal subcutis, leading to the clinical finding of “skin tightening” and loss of normal skin folds.
- Cardiac Involvement: Myocardial fibrosis can cause arrhythmias and cardiomyopathy, independently worsening the patient’s prognosis.