What is a cutaneous horn?
While around 60 percent of cutaneous horns are benign, the remaining percentage are cancerous or precancerous. Because of this, anyone with a cutaneous horn should seek medical attention.
What does it look like?
A cutaneous horn may look and feel similar to an animal's horn.
Image credit: Jojo (2013, May 27).
Cutaneous horns are skin tumors that resemble an animal's horn. It is hard and yellowish-brown in color.
To be called a horn, the height must be at least one half of the largest diameter. In very rare cases, a horn may be large, like the horn of an animal.
However, a cutaneous horn is very different from an animal's horn. Animal horns form around a centrally located bone, while cutaneous horns, including giant cutaneous horns, do not.
Usually, only a single horn will grow. They are most likely to appear on the face, ears, and the back of the hand in older people. Nail horns may also develop, especially on the big toe. Rarely, a horn may occur on the penis.
Occasionally, the growths look like coral or wood.
Causes and risk factors
Scientists are not sure of the causes of cutaneous horns. However, they do believe that there is a link between high levels of radiation exposure and an increased likelihood of developing a cutaneous horn.
Because cutaneous horns often appear on the face and hands, some researchers also believe there may be a link between sun exposure and the likelihood of developing a cutaneous horn. This is because both of these areas receive a higher level of sun exposure than other parts of the body.
Researchers believe certain people may be at greater risk for developing a cutaneous horn, though developing a cutaneous horn can happen to anyone. Higher-risk groups include:
- people with fair skin
- those with human papillomavirus (HPV)
- older adults
- individuals with a lot of sun damage
Men are not only more likely than women to develop a cutaneous horn when they are younger, but they are also more likely to have a malignant cutaneous horn.
Cutaneous horns found on the face are more likely to be cancerous or precancerous than cutaneous horns located elsewhere on the body. Giant cutaneous horns are also more likely to be cancerous than smaller horns.
A doctor can often diagnose a cutaneous horn based on its physical appearance alone. Most cutaneous horns share the following characteristics:
- a curved brown or yellow horn-like growth on the surface of the skin
- surrounded by normal or slightly thickened skin
- usually at least twice as tall as it is wide
- often only one appears, though in rare occasions they may grow in groups
- often small, though giant horns exist
- most common on face, hands, forearms, and ears
Most cutaneous horns do not cause any symptoms other than the horn itself. However, because the horn sticks out from the surface of the skin, it may become injured. When a horn is damaged, it may cause pain or become infected.
When to see a doctor
Anyone who discovers a cutaneous horn should schedule an appointment with a doctor to have the horn evaluated for cancer.
Those who have existing cutaneous horns that have already been seen by a doctor should schedule another appointment promptly if any of the following symptoms develop:
- an increase in size
- redness at the base of the horn
- the horn becomes wider than it is tall
- hardened or puckered skin surrounds the horn
The above symptoms indicate that the horn may have become cancerous.
Associated conditions and complications
There are many other conditions that doctors associate with cutaneous horns. The conditions and complications range from benign to cancerous.
Conditions associated with cutanous horn include psoriasis, viral skin infections, Bowen's disease, and arsenical keratosis.
Benign conditions associated with cutaneous horns include:
- pigmented growths on the skin called nevuses
- harmless, warty growths on the skin known as seborrhoeic keratosis
- viral warts not related to HPV
- viral skin infections, such as molluscum contagiosum
While these conditions are not cancerous, some of them may require medical treatment. These conditions include the viral skin infections and psoriasis.
More serious conditions associated with cutaneous warts include:
- squamous cell carcinoma or Bowen's disease
- basal cell carcinoma
- melanoma (very rarely)
- intraepidermal carcinoma
- arsenical keratosis
Another growth, keratoacanthoma, is a lesion that resembles a small volcano. It can grow up to 2 centimeters (cm) in diameter in sun-damaged skin. It may start as a small pimple, then develop over a few months, before shrinking.
A doctor may recommend surgery to reduce the risk of it becoming malignant, as it can resemble squamous cell carcinoma (SCC).
Almost all cutaneous horns will be biopsied to rule out malignancies.
A doctor will take a sample of the horn that includes a piece of the base. After the procedure, the horn will then be sent to a laboratory for further testing and examination to verify the diagnosis and determine whether it is cancerous or benign.
During a diagnostic biopsy, a doctor may remove the entire cutaneous horn depending on its size.
During the procedure, the person receives a local anesthetic to numb the horn and the area around the horn. Once the area is numb, a doctor will cut away the horn from its base to remove it from the skin.
A doctor may also remove layers of the skin around or under the horn and will then close the area.
Further treatment depends on the results of the biopsy. If the cutaneous horn is cancerous, doctors will recommend further checks to make sure cancer has not spread.
For some cutaneous horns, cryosurgery, or removing the horn through extreme cold, may be considered.
During cryosurgery, a doctor gives the person a local anesthetic and then applies liquid nitrogen through either a swab or spray to the horn. This damages the tissues making up the horn. The horn will then eventually fall off.
Doctors choose cryosurgery most often for horns caused by specific conditions, including actinic keratosis, verruca vulgaris, and molluscum contagiosum.
Once a horn is removed, the outlook is usually good, even for people with cancerous cutaneous horns. Most people do not need further treatment for a cutaneous horn after its removal.
However, those who discover basal cell or squamous cell cancer as the horn's underlying cause will need to be screened regularly in case the cancer returns.