Pathology of Keratoacanthoma
Keratoacanthoma was first described in 1889 by Jonathan Hutchinson.
He described the lesion as 'crateriform ulcer of face'.
Keratoacanthoma is a controversial cutaneous tumour that usually occurs in elderly patients.
Males are more often affected than females.
Keratoacanthomas often occur spontaneously as a single rapidly growing tumour on sun-exposed skin.
Multiple keratoacanthomas are rarely seen.
Keratoacanthomas may also develop after trauma, laser resurfacing, radiation therapy, and at the donor site after skin grafting.
This lesion grows rapidly to the size of 1-2 cm over a period of one to
two months and tend to resolve spontaneously after several weeks to
months leaving an atrophic scar.
The lesion presents as solitary nodule with a central keratin plug.
The histologic differential diagnosis of keratoacanthoma is principally with well differentiated squamous cell carcinoma.
The following features favour the diagnosis of keratoacanthoma over squamous cell carcinoma.
- Rapidly growing lesion with a characteristic low power appearance of a crateriform lesion with central keratinous plug.
- Cytological pleomorphism is less common.
- The cytoplasm has a glassy, pale eosinophilic appearance.
- There is an abrupt transition between the lesion and adjacent epidermis and a sharp outline between the tumour nests and stroma.
- Absence of stromal desmoplasia.
- Presence of intraepithelial elastic fibres and intracytoplasmic
- Giant keratoacanthoma ;
- Keratoacanthoma centrifugm marginatum (multinodular keratoacanthoma);
- Subungual keratoacanthoma ;
- Multiple Keratoacanthoma.
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