Synopsis
Recognise the rapidly growing crateriform keratoacanthoma pattern, understand why it cannot be safely distinguished from well-differentiated SCC clinically, and arrange urgent complete histological assessment.
- A classic keratoacanthoma is a rapidly growing, symmetrical, dome-shaped nodule with a central keratin-filled crater on sun-exposed skin.
- Growth over two to eight weeks is typical, but speed does not prove benignity; SCC can show the same crateriform pattern.
- Manage a solitary suspected keratoacanthoma as SCC until complete architecture and depth have been assessed histologically.
Key red flags
Rapid growth, pain, lip or ear site, size over 2 cm, immune suppression, recurrence, fixation, neurological symptoms or a regional node increases SCC risk and requires urgent specialist assessment.
Increase from papule to centimetre-scale tumour within several weeks is characteristic and itself triggers urgent assessment.
Investigation priorities
Assess full crater architecture, invasive front, differentiation and margins while treating the lesion.
Management branches
A rapidly growing keratin-filled nodule is clinically compatible with keratoacanthoma.
- Document growth, site, size, neurological symptoms, immune state and nodes and make an urgent suspected-cancer referral.
- Arrange complete excision with adequate depth when feasible, preserving the specimen and orientation for histopathology.