Scleroderma questions love to test whether you can sort limited vs diffuse systemic sclerosis in 5 seconds—because that single decision predicts organ involvement, antibodies, and causes of death. Here’s a quick visual hack you can reuse on test day and in the hospital.
The 5-second “Map + Speed” visual hack
Step 1: Draw the body “map”
Think of systemic sclerosis as skin fibrosis spreading on a map:
- Limited = stays at the edges (distal)
- Face + fingers (± forearms)
- Diffuse = spreads inward (proximal)
- Trunk + proximal extremities (upper arms, thighs)
Step 2: Add the “speed” rule
- Diffuse = fast & furious internal organs
- Limited = slow burn, later complications
One-liner to memorize:
Limited = distal skin + late PAH. Diffuse = proximal skin + early lung/kidney.
Mnemonic that actually separates them: “CREST = CREEPS (slow)”
Limited systemic sclerosis = CREST
Calcinosis
Raynaud phenomenon
Esophageal dysmotility
Sclerodactyly
Telangiectasias
Why it helps: CREST features feel like “peripheral/vascular + GI” problems—not immediate visceral catastrophe.
High-yield antibody: Anti-centromere
- Classically tied to limited disease
- Board-style association: later pulmonary arterial hypertension (PAH)
Diffuse systemic sclerosis: “Diffuse = DOA organs early”
Diffuse systemic sclerosis tends to have:
- Widespread skin thickening (includes trunk)
- Early visceral fibrosis
- Lungs: interstitial lung disease (ILD) → restrictive pattern
- Kidney: scleroderma renal crisis
- Heart: arrhythmias/heart failure (myocardial fibrosis)
High-yield antibody: Anti–topoisomerase I (Scl-70)
- Strong association with diffuse disease and ILD
Also high-yield: Anti–RNA polymerase III
- Linked to diffuse disease and scleroderma renal crisis (classic test pairing)
Limited vs diffuse: the USMLE table you want in your head
| Feature | Limited (CREST) | Diffuse |
|---|---|---|
| Skin distribution | Distal (fingers/face), ± forearms | Proximal + trunk |
| Speed | Slow progression | Rapid progression |
| Key antibody | Anti-centromere | Anti–Scl-70 (topoisomerase I), anti–RNA pol III |
| Lung disease | PAH (late) > ILD | ILD (early) |
| Kidney | Less common renal crisis | Renal crisis risk ↑ |
| Cause of major morbidity/mortality | PAH/right heart failure | ILD, renal crisis, cardiac involvement |
What “scleroderma renal crisis” looks like (test favorite)
Clue cluster: diffuse disease + abrupt hypertension + AKI
- Malignant HTN
- Acute kidney injury
- Microangiopathic hemolytic anemia (MAHA) may be present
Treatment you should not miss:
- ACE inhibitor (e.g., captopril) even if creatinine rises initially
Board trap: high-dose steroids can increase risk of renal crisis in systemic sclerosis.
The lung split: ILD vs PAH in one glance
Diffuse → interstitial lung disease
- Restrictive PFTs: ↓ TLC, ↓ FVC
- ↓ DLCO (often early)
- Imaging: fibrosis (e.g., basilar reticular changes; honeycombing in advanced disease)
Limited → pulmonary arterial hypertension
- Often presents later with exertional dyspnea, fatigue, syncope
- Echo may show elevated pulmonary pressures; confirm with right heart cath
- DLCO can drop as PAH develops
Shortcut:
- Scl-70 = Scarring lungs (ILD)
- Centromere = Central pressure problem (PAH)
Raynaud + skin tightening: what’s actually happening?
Systemic sclerosis is driven by:
- Immune activation (autoantibodies)
- Endothelial dysfunction (Raynaud, telangiectasias, PAH risk)
- Fibroblast activation → collagen deposition (skin thickening, organ fibrosis)
That’s why vascular symptoms often show up early, while fibrosis-related organ failure depends on the subtype and timeline.
Rapid-fire exam pearls (high yield)
- Limited = CREST + anti-centromere + late PAH
- Diffuse = proximal skin + anti–Scl-70 (ILD) + anti–RNA pol III (renal crisis)
- Scleroderma renal crisis → ACE inhibitor
- Esophageal dysmotility is common (GERD, dysphagia); think smooth muscle atrophy + fibrosis
- Think “restrictive” when diffuse disease hits lungs (ILD)
Quick self-check (USMLE-style)
Patient with tight skin on fingers/face, telangiectasias, long history of Raynaud, now progressive dyspnea.
Most likely complication? Pulmonary arterial hypertension (limited/CREST, anti-centromere).
Patient with rapidly progressive skin thickening including trunk + new severe hypertension + AKI.
Next step? Start ACE inhibitor (scleroderma renal crisis; often anti–RNA pol III).