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.
Sources
Based on clinical guidelines from the American Academy of Dermatology (AAD) and British Association of Dermatologists (BAD). Statistics from NCI SEER Program and IARC GLOBOCAN. Staging per AJCC Cancer Staging Manual, 8th ed. Full methodology