Erosion

What is it?

An erosion is a shallow, open area of skin where the outermost layer (epidermis) has been partially or completely lost, but the damage does NOT extend below the basement membrane (the boundary between the epidermis and the deeper dermis). Think of it as a superficial "scrape" — like the raw area left after a blister roof breaks. The key clinical significance of erosions is that they heal without scarring, because the structures needed for skin regeneration remain intact. This distinguishes them from ulcers, which extend deeper and often heal with scarring.

What does it look like?

Erosions have characteristic features:

• Surface: Moist, glistening, raw-looking area — may weep clear fluid
• Depth: Shallow — level with or slightly depressed below the surrounding skin
• Color: Pink to red, matching the underlying dermis
• Borders: Often round or oval (following the shape of a preceding blister), or irregular (from scratching)
• Size: Variable — from a few millimeters to several centimeters
• Base: Smooth, clean base without necrotic (dead) tissue
• Crusting: May develop a thin crust as the serous fluid dries
• Pain: Often tender or stinging, especially on contact

Where does it appear?

Erosions develop in characteristic locations depending on the cause:

• Mouth and oral mucosa: Pemphigus vulgaris, herpes simplex, aphthous ulcers, erosive lichen planus
• Trunk and extremities: After rupture of blisters in pemphigoid or pemphigus
• Face and lips: After herpes simplex vesicles break
• Skin folds: Intertrigo (groin, axillae, under breasts) — moisture-related erosion
• Genitals: Erosive lichen planus, herpes infections
• Widespread: Severe blistering diseases, toxic epidermal necrolysis

Associated features

Erosions may be accompanied by:

• Preceding blisters or vesicles that ruptured to leave the erosion
• Crusting as the erosion begins to heal
• Surrounding erythema (redness)
• Pain or burning sensation
• Positive Nikolsky sign (skin slides with gentle lateral pressure — pemphigus)
• Multiple erosions appearing over time
• Intact blister roofs at the edges of erosions
• Quick healing (days to a few weeks) without scarring

When to see a doctor

Seek medical evaluation for:

• Multiple erosions appearing without clear cause (possible autoimmune blistering disease)
• Persistent oral erosions that do not heal within 2-3 weeks (possible pemphigus or erosive lichen planus)
• Widespread erosions with skin peeling (possible drug reaction — urgent)
• Erosions that appear to be deepening (possible progression to ulceration)
• Signs of infection: increased pain, pus, expanding redness, fever
• Erosions in the mouth that make eating or drinking difficult
• Genital erosions — always need evaluation to exclude serious causes