Porokeratosis
Ring-like lesions with a distinctive raised ridge border. 7-11% lifetime SCC risk.
What to look for
Side-by-side comparison
Normal skin
No ring lesions
Porokeratosis
Ring with raised ridge border
Porokeratosis is characterized by well-defined patches surrounded by a distinctive thin raised ridge (cornoid lamella) - a column of abnormal keratin.
Disseminated superficial actinic porokeratosis (DSAP) is the most common variant: multiple small ring-like lesions on sun-exposed arms and legs. Classic porokeratosis of Mibelli presents as a single larger plaque.
The estimated 7-11% lifetime SCC risk means monitoring is important, particularly for larger, longstanding, or immunosuppressed cases.
Quick self-check
Does this look like porokeratosis? Answer 2 questions.
Does the lesion have a ring shape with a thin raised ridge border?
Has it been present for months to years?
Risk factors
- Genetic predisposition
- Immunosuppression
- Chronic sun exposure (DSAP variant)
- Older age
When to see a dermatologist
- ⚠Ring-like skin lesions with a raised border
- ⚠Any lesion within porokeratosis that thickens, ulcerates, or changes
- ⚠Porokeratosis in immunosuppressed patients
Often confused with
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Full ABCDE check →Frequently asked questions
Can porokeratosis become cancer?
Yes. 7-11% lifetime SCC risk. Higher for larger, longstanding lesions, linear variant, and immunosuppressed patients.
How is it different from ringworm?
Both ring-shaped, but porokeratosis has a distinctive thin hard ridge (cornoid lamella) versus ringworm's scaly inflammatory ring. Porokeratosis does not respond to antifungals.