Keratoacanthoma: Understanding Symptoms, Causes, and UK Management

A keratoacanthoma (KA) is a common skin growth that primarily appears on sun-damaged skin. In the UK, these lesions are often encountered in dermatology clinics because of their striking appearance and incredibly fast growth rate. Typically, a keratoacanthoma begins as a small, red papule and, within just three to four weeks, can grow into a dome-shaped nodule with a central crater filled with keratin (a protein found in the skin).

This central plug gives the lesion its classic 'volcano-like' appearance. While many cases of keratoacanthoma eventually resolve on their own if left for several months, UK clinical practice following NICE guidelines generally involves active treatment. This is because these lesions look almost identical to a type of skin cancer called Squamous Cell Carcinoma (SCC). Without a biopsy, it is extremely difficult for even an experienced doctor to tell them apart with 100% certainty.

Identifying a keratoacanthoma early is essential for peace of mind and effective management. Most patients notice these growths on areas of the body that receive the most sunlight, such as the face, forearms, and the backs of the hands. Common characteristics include:

• Rapid Growth: The lesion may reach a size of 1cm to 2cm within a few short weeks.
• Shape: A firm, dome-shaped lump with a distinct central plug of hard, scaly material.
• Colour: Usually flesh-coloured or slightly pink/red.
• Sensation: They are generally painless, though they may feel tender if caught on clothing or if they become inflamed.

Because they grow so quickly, they often cause significant anxiety for patients. If you notice a new lump that is changing shape or size every few days, it is important to book a consultation with a GP or speak to an online doctor for an urgent review.

The exact cause of keratoacanthoma is not fully understood, but clinical evidence suggests several contributing factors. The primary driver is ultraviolet (UV) radiation from the sun or tanning beds. This explains why they are more prevalent in older populations in the UK who may have accumulated decades of sun damage.

Other risk factors include:

• Age: Most commonly seen in those over 50.
• Skin Type: People with fair skin (Type I or II on the Fitzpatrick scale) are at higher risk.
• Immunosuppression: Individuals taking medication to suppress the immune system (e.g., after an organ transplant) may develop multiple lesions.
• Chemical Exposure: Historical exposure to certain tars or mineral oils has been linked to these growths.
• Previous Skin Trauma: They sometimes develop at the site of a minor injury or scar.

The most important aspect of keratoacanthoma is its relationship with Squamous Cell Carcinoma (SCC). Many pathologists actually categorise KA as a 'well-differentiated SCC, keratoacanthoma type.' For a British patient, this means the NHS treats the lesion as a potential malignancy until proven otherwise.

When you see a GP or an online doctor, they will examine the lesion using a dermatoscope. If they suspect a keratoacanthoma, the standard UK pathway is an urgent referral (often the 'two-week wait' pathway) to a dermatologist. A definitive diagnosis is usually made through an excisional biopsy, where the entire lesion is removed and sent to a laboratory for microscopic examination. This ensures that a true SCC has not been missed.

If you are worried about a skin growth but cannot get an immediate appointment at your local surgery, you can speak to a GP online for a prompt assessment. An online doctor can provide a visual review of the lesion via high-quality photographs or video consultation.

During an online GP consultation for skin concerns, the doctor will:

• Assess the history of the lesion (how long it has been there and how fast it is growing).
• Review your risk factors and medical history.
• Explain whether the lesion meets the criteria for an urgent secondary care referral.
• Provide a private referral letter if necessary for faster specialist review.
• Offer advice on managing the area while waiting for treatment.

Seeking early advice for rapidly growing skin lesions is always the safest course of action, as early intervention leads to the best cosmetic and health outcomes.

While some keratoacanthomas can heal on their own, the process leaves a significant scar and takes many months. Therefore, treatment is usually recommended. Options include:

• Surgical Excision: The most common method. The lesion is cut away under local anaesthetic. This is the preferred method as it allows for full lab testing.
• Curettage and Cautery: The lesion is scraped away and the base is heat-treated to stop bleeding and kill remaining cells.
• Cryotherapy: Freezing the lesion with liquid nitrogen, though this is less common for KA as it doesn't allow for a biopsy.
• Topical or Intralesional Treatments: In rare cases where surgery isn't possible, creams or injections may be used to shrink the growth.

Following removal, the wound will usually require stitches and a dressing. Your healthcare provider will give you specific aftercare instructions to minimise scarring and prevent infection.