Keratoacanthoma is a rapidly growing epidermal tumour that resembles squamous cell carcinoma both clinically and histologically.
It is believed to arise from hair follicles. There is little evidence that keratocanthoma has malignant potential but it may mimic histological features of squamous cell carcinoma.
Trauma, viral infection, sun exposure, and chronic exposure to tar, pitch and petroleum have all been implicated as aetiologic agents.
In keratocanthoma (molluscum sebaceum), a firm nodule, appears singly on the skin and grows to around 2 cm across in about six weeks, gradually disappearing during the next few months.
Men are affected more than women, commonly between the ages of 50 and 70.
Keratoacanthomas occur on the nose, face, hands and fingers and sometimes on the scalp or neck.
The cause is not well-known. Although the nodules disappear spontaneously they may leave an unsightly scar, therefore treatment by curettage, cautery or excision and sucture is often carried out.
Surgical excision is thought to produce less scarring than leaving the lesion to resolve spontaneously.