Two thirds of keratoacanthomas occur on the face; the rest occur elsewhere including the ears (usually sun damaged, hair bearing skin). They arise from hair follicle skins cells for unknown reasons. The lesions usually start as a small pink papule which rapidly enlarges over the following few months. Eventually (6-12 months), the lesions spontaneously regress, leaving an ugly scar. Many are removed to exclude squamous cell carcinomas (SCCs) and to prevent scarring.
Key learning points from the video
- 74-year-old patient with an evolving lesion on his left arm
- Lesion on the patient started as a small scaling lesion on the arm
- Developed by building up around the base with a central evolving area
- Likely that under the scale will be ulceration
- Diagnosis of keratoacanthoma variant of a squamous cell carcinoma derived from pilosebaceous cells
- For excision it requires good surgical margins but taking as little tissue as possible
- Langer’s lines or skin tension lines will dictate the direction of the excision
- Lignocaine with adrenaline can be used for local anaesthetic
- Elliptical excision is required in this case in one fluid motion
- Cut down to subcutaneous tissue so the lesion is floating up
- Keratoacanthomas generally do not extend deeper into underlying tissues
- Start from the apex and work backwards once lateral excisions in place
- It is important to see subcutaneous flat underneath the lesion with a yellow sheen underneath
- Check for any signs that invasion has occurred under the lesion
- It is important to ensure the excision is deep enough so that closure is made easier
- Suture lesion at the two thirds and third point to then close across the middle
