Keratoacanthoma. The clinical picture is typical and so is the history: a tumour that has grown in a few weeks and is rapidly increasing in size, with a high collar and a keratinized central top. In this case, the tumour was treated with powerful liquid nitrogen cryotherapy. The patient should be referred without delay to a specialist who is acquainted with the special features of this tumour (ENT or dermatology). Waiting two weeks may mean that the tumour will be doubled in size.