What Is Tree Man Syndrome?

Tree man syndrome or epidermodysplasia verruciformis (EV) is a rare inherited health condition. It causes wart-like skin growths resembling tree bark and is linked to a high risk of skin cancer. Only about 200 cases have been identified since it was first discovered.

The bark-like growths are extremely painful and disfiguring. They can become quite large, which leads to substantial disability. Surgery can help, but the growths may come back.

This article discusses the symptoms, causes, and treatment options for tree man syndrome.

Tree Man Syndrome Symptoms

The major symptoms of tree man syndrome are growths on the skin. They generally appear on the face, neck, torso, hands, and feet.

Growths are usually widespread but may be confined to a single hand or foot, or face. They can extend deep under the skin, where they cause pain by putting pressure on your nerves.

Several types of skin problems are possible, including:

• Flat, flaky, or scaly, reddish-brown areas of skin (macules)
• Small, raised, solid pimple-like bumps (papules)
• Horn-like or bark-like growths on the skin, which can be extremely painful
• Skin cancer

Some cases of tree man syndrome involve extremely large, hard protein growths called keratin. It's the same material that makes up horns, hooves, claws, and fingernails.

All of these problems occur because EV makes you especially susceptible to the human papillomavirus (HPV).

Causes

EV can be genetic or acquired. They’re classified based on causes, which involve infection with certain strains of HPV plus either a genetic mutation or a compromised immune system.

Genetics and Tree Man Syndrome

The genetic form of EV usually develops early in life, before age 20. Sometimes, though, it shows up as late as middle age.

The condition is believed to be caused by a genetic mutation that impairs your immune system’s response to certain viruses, including a strain of HPV. This allows those viruses to spread. The mutation is believed to be recessive, meaning you must receive the gene from both parents. Your parents can pass along the gene whether or not they have symptoms.

About 75% of people with EV have mutations in one of two genes, which are called EVER1 and EVER2. The other 25% comprises non-genetic cases and mutations in several genes that allow for extensive HPV replication. These genes are called:

• RHOH
• MST1
• CORO1A
• IL-7

Acquired Tree Man Syndrome

Acquired EV occurs in people with compromised immune systems, which may be from:

• HIV/AIDS (the most common cause)
• Some blood disorders
• Immunosuppressant medications

HPV

In the United States, HPV is the most common sexually transmitted infection (STI). It can also lead to cervical, genital, and anal cancer. A vaccine exists to prevent the strains known to cause these types of cancer.

EV is related to different strains of HPV, which infect the skin. They’re called beta-HPVs. Strains known to be involved in EV are HPV types 5, 8, and 10.

So far, no vaccine exists for these strains, but researchers have called for the development of one.

Diagnosis

EV is often diagnosed on sight because of its characteristic appearance. Healthcare providers may confirm the diagnosis with a biopsy, in which a small amount of tissue is removed and evaluated at a lab.

EV growths have certain characteristics that are visible under a microscope. Also, the type of HPV can generally be identified.

Treatment

There is no cure for EV. However, some treatments can be successful. They include:

• Growth removal: This may involve chemicals, cryotherapy (freezing), electrosurgery, or laser ablation. It may need to occur periodically due to regrowth.
• Retinoid medications: Oral (by mouth) or topical (on the skin) forms are available. One example is Claravis (isotretinoin).
• Cancer surgery: Removal of tumors and reconstruction are options for invasive skin cancers.

Protecting yourself from the sun is also important because exposure can make cancer more likely. This includes avoiding direct sunlight, wearing protective clothing, and using sunscreen.

Your healthcare team may want to change your medications if you have acquired EV after a transplant.

For How Long Can You Live With Tree Man Syndrome?

Tree man syndrome doesn't shorten your life expectancy unless you have untreated cancer. The prognosis is better when the condition is diagnosed and treated early. The goal is to prevent or treat skin cancer.

Though growths can be removed, they usually come back later. Expect periodic removals as well as lifelong treatment.

Summary

Tree man syndrome, or EV is a rare condition that causes several types of skin growths, the most distinctive of which are large, painful, bark-like growths. HPV skin infections, certain genetic mutations, or compromised immune systems can cause it. EV is diagnosed on sight and possibly a tissue biopsy. Treatments include growth and tumor removal and retinoid medications. Bark-like growths may come back, requiring more surgeries. Early diagnosis and treatment lead to better outcomes.