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.
- Urgent complete excision is preferred when feasible because partial punch or superficial shave may not show the diagnostic shoulders and deep interface.
- Do not observe for spontaneous regression when SCC cannot be excluded, especially in immune suppression or high-risk sites.
- Palpate regional nodes and ask about pain, numbness and weakness in a rapidly growing keratinising tumour.
- Multiple synchronous lesions should trigger medicine, immune and family-history review and specialist dermatology care.
- Destructive treatment such as curettage or cryotherapy without adequate histology risks erasing an SCC diagnosis.
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.
Irregular infiltration, fixation, neurological symptoms, lip or ear location, recurrence or palpable nodes heightens SCC concern.
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.
- Review the definitive report and manage margins and surveillance according to the SCC risk assessment.