Nevus Simplex vs Port-Wine Stain: Key Distinguishing Features
Nevus simplex (salmon patch) and port-wine stain are both flat capillary malformations, but they differ fundamentally in appearance, borders, natural history, and clinical significance 1.
Clinical Differentiation
Nevus Simplex (Salmon Patch/Stork Bite)
- Appearance: Flat, pink or light red capillary malformation
- Borders: Poorly defined, ill-defined borders 1
- Color: Pink to light red ("salmon" colored)
- Natural history: Present in up to 43% of the general population; typically fades or disappears completely in approximately 50% of cases during the first years of life 1, 2
- Common locations:
- Clinical significance: Generally benign with no associated complications when located in typical sites (glabella, nape, eyelids)
Port-Wine Stain (PWS)
- Appearance: Flat, darker vascular lesion
- Borders: Well-defined, sharp borders 1
- Color: Darker red to red-purple 1
- Natural history: Permanent - does not involute; tends to darken and thicken over time 1
- Common locations: Can occur anywhere, often follows trigeminal nerve distribution on face 4
- Clinical significance: Persistent cosmetic concern; may develop nodules with age; can be associated with underlying syndromes (e.g., Sturge-Weber syndrome when in trigeminal distribution)
Risk Stratification Context
When these lesions appear in the lumbosacral midline region, the clinical significance changes dramatically 1:
- Nevus simplex: Classified as intermediate-risk cutaneous marker for spinal dysraphism when located in midline or juxta-midline lumbosacral areas
- Port-wine stain: Also classified as intermediate-risk in the same location
- Both may warrant imaging evaluation when overlying the spine, particularly if accompanied by other cutaneous markers
Practical Clinical Pearls
The single most reliable distinguishing feature is border definition: if you can clearly trace the edge of the lesion with your finger, it's likely a port-wine stain; if the borders blend gradually into normal skin, it's likely nevus simplex 1.
Color intensity is secondary but helpful: nevus simplex appears lighter (pink/salmon), while port-wine stains are darker (red-purple) and become progressively darker with age 1.
Location provides prognostic information: Nevus simplex in typical locations (glabella, nape, eyelids) requires no intervention and often resolves spontaneously. Port-wine stains never resolve spontaneously and may require laser therapy (pulsed dye laser) for cosmetic management 5.
Common Diagnostic Pitfall
Do not confuse either of these flat capillary malformations with infantile hemangiomas, which are raised, highly vascular lesions with well-defined borders that proliferate postnatally 1. Infantile hemangiomas are vascular tumors, not malformations, and have a completely different natural history and management approach.