Systemic Sclerosis (Scleroderma): Overview & Learning Objectives
A world-class, guideline-referenced introduction to the most lethal autoimmune rheumatic disease — built for medical students preparing for clinical clerkships, USMLE/PLAB, and real-world scleroderma clinics.
1.1 High-Yield Clinical Significance
Systemic sclerosis (SSc), historically called scleroderma, is an orphan autoimmune connective tissue disease characterized by three intertwined pathologic processes acting on virtually every organ system: microvascular injury (vasculopathy), autoimmunity/inflammation, and progressive fibrosis of the skin and internal organs. [Harrison’s, Ch. 360] Although the name “scleroderma” evokes skin thickening, the term SSc is preferred because visceral, not cutaneous, involvement drives prognosis. [EULAR 2023]
Key epidemiologic facts
- Estimated incidence: 9–46 new cases per million per year; prevalence in the U.S. approaches 100,000 cases, although true prevalence is likely underestimated because a substantial proportion of patients do not fulfil formal classification criteria. [Harrison’s, Ch. 360] In the UK, roughly 1,000 new cases are diagnosed per year. [BSR 2024]
- Female predominance of about 4.6:1, most pronounced during the childbearing years and declining after menopause — pregnancy and first-degree family history of SSc each independently raise disease risk (up to 13-fold for a first-degree relative). [Harrison’s, Ch. 360]
- Race/ethnicity: Black patients have higher age-specific incidence and mortality, more frequently develop diffuse cutaneous disease and ILD, tend to have earlier disease onset, and generally have a worse prognosis. [Harrison’s, Ch. 360]
- Juvenile-onset SSc (jSSc), defined as onset of the first non-Raynaud manifestation before age 18, is exceedingly rare (prevalence ~3 per 1,000,000) but carries important differences from adult disease, including more frequent overlap features. [BSR 2024]
- Around 1 in 3 people with SSc develop ILD and 1 in 10 develop pulmonary hypertension — together the leading direct causes of SSc-related death. 1 in 5 develop an overlap connective tissue disease requiring parallel management. [BSR 2024]
The disease at a glance: two major clinical subsets
| Feature | Limited Cutaneous SSc (lcSSc) | Diffuse Cutaneous SSc (dcSSc) |
|---|---|---|
| Skin involvement | Indolent onset; limited to fingers, distal to elbows/knees, face; slow progression | Rapid onset; extremities, trunk; rapid progression |
| Raynaud’s phenomenon | Antedates skin involvement, sometimes by years | Onset coincident with or shortly before skin involvement |
| Interstitial lung disease | Slowly progressive, generally mild | Frequent, early onset, can progress and be severe |
| Scleroderma renal crisis | Very rare | Occurs in ~5% (early, <4 years disease duration) |
| Characteristic autoantibody | Anti-centromere | Anti-topoisomerase I (Scl-70), anti-RNA polymerase III |
Adapted from Harrison’s Table 360-3 and Table 360-4.
A minority of patients present with the hallmark serologic and vascular features of SSc (Raynaud’s phenomenon, SSc-specific autoantibodies) yet lack cutaneous sclerosis — a benign disease subset termed SSc sine scleroderma. [Harrison’s, Ch. 360]
1.2 Learning Objectives (Mapped to Bloom’s Taxonomy)
1.3 How This Module Fits Into the Course
This overview is Module 1 of a 13-module systemic sclerosis curriculum. Each subsequent module builds toward full clinical competency — from molecular pathogenesis, through pattern recognition on imaging, to guideline-concordant management and USMLE/PLAB-style mastery testing. Bookmark this page as your anchor: every later module will refer back to the subsets, epidemiology, and objectives defined here.