Porokeratosis

Porokeratosis is a group of skin conditions that cause circular, discolored skin lesions with rough borders. Experts don’t fully understand the exact cause. But they think it may occur when a group of abnormal keratinocytes produces an abnormal skin growth. Keratinocytes are the main type of cell in your outer layer of skin (epidermis). They produce the protein keratin, which helps support your skin and keeps your nails and hair healthy. When your body makes too many keratinocytes, these cells build up on the surface of your skin.

Porokeratosis (pronounced “pawr-oh-ker-uh-TOH-sis”) isn’t common. Depending on the type, lesions may appear on areas that get a lot of sun. These include your:

• Shoulders
• Arms
• Legs
• Back
• Torso

The lesions can be precancerous. This means they aren’t cancer. But they may have signs that suggest they’re likely to become cancer if you don’t get treatment. There’s no cure for porokeratosis. But treatment may help improve the appearance of lesions, reduce symptoms or treat lesions at higher risk for developing skin cancer.

Types

There are many different types of porokeratosis. The most common types include:

• Disseminated superficial actinic porokeratosis (DSAP): Lesions are small — usually between 2 and 5 millimeters in diameter — and affect areas that get a lot of sun. They’re round with a thin, raised border and may itch. DSAP usually appears in your 30s or 40s.
• Porokeratosis of Mibelli (PM): Lesions are skin-colored, pink or brown and have a round, raised border. They usually appear on your arms, legs and torso. They can range in size from a few millimeters to a few centimeters. This type usually starts during infancy or childhood. But it can develop later in life.

Rarer types include:

• Disseminated superficial porokeratosis (DSP): The lesions look similar to those in DSAP. But they may appear anywhere on your body, not just the areas that get a lot of sun.
• Disseminated superficial porokeratosis of immunosuppression: Lesions appear when your immune system isn’t working as expected (immunocompromised). They may appear after certain conditions or treatments that suppress the immune system. Examples include an organ transplant, chemotherapy or other medications.
• Linear porokeratosis: Lesions appear along linear streaks with raised borders (Blaschko lines). Linear porokeratosis usually appears during infancy or childhood. This form has a higher risk of developing into skin cancer than some other types of porokeratosis.
• Porokeratosis palmaris et plantaris disseminata (PPPD): Lesions first appear on the palms of your hands and soles of your feet. They may later spread to other areas of your body. PPPD usually appears during adolescence or early adulthood.
• Eruptive pruritic papular porokeratosis: Small, raised lesions appear suddenly on your arms, legs and torso. They’re often very itchy. This form typically develops in adults.

What does porokeratosis look like?

Each type may look slightly different. But the main features are skin bumps that are:

• Small, thin and round
• Scaly or dry
• Discolored (red or brown) or around the same color as the surrounding skin

The lesions also have ridge-like borders that are rough and slightly raised. They may be itchy. Over time, they may increase in number and expand into larger patches.

Porokeratosis can appear anywhere on your skin. But it most commonly affects areas that get a lot of sun. You may only have a few lesions, or you may have over 100.

Causes

Experts believe genetic variations contribute to it. They don’t know exactly what causes the variations. But certain triggers may make porokeratosis worse. These include:

• Exposure to sunlight, ultraviolet (UV) rays and other forms of radiation
• Taking corticosteroids or immunosuppressants for a long time
• Long-term rubbing, scratching or other types of skin injury

Risk factors

You have a greater chance of getting porokeratosis if you:

• Have lighter skin
• Get a lot of sun
• Have a weakened immune system or take medications that suppress your immune system

Complications

There’s a chance that porokeratosis can lead to skin cancer. Some people develop squamous cell carcinoma or basal cell carcinoma. The more time you spend in the sun or the more exposure you have to UV rays or other forms of radiation, the more your risk of developing skin cancer increases.

How doctors diagnose porokeratosis

Healthcare providers will first review your health history and ask about any symptoms. Then, they’ll examine the lesions. They often use a handheld instrument (dermatoscope) to take a closer look at your skin. They can usually make a porokeratosis diagnosis with a physical exam. But they may also remove a sample of skin tissue (skin biopsy) to confirm the diagnosis.

Your provider may refer you to a dermatologist.

How is porokeratosis treated?

In many cases, lesions usually expand slowly and don’t cause any troublesome symptoms. Your healthcare provider may not recommend treatment at first. But they’ll want to see you regularly (active surveillance) to look out for any changes.

If porokeratosis causes symptoms or bothers you, your provider may recommend creams or ointments that you rub on the lesions. These may include:

• Keratolytics
• 5-fluorouracil
• Imiquimod 5%
• Retinoids
• Corticosteroids

They may also recommend treatments like:

• Cryotherapy
• Laser resurfacing
• Dermabrasion

It’s important to note that not all treatments work for everyone. It may take a few tries to figure out which treatment works best for you. It’s also possible that none of the treatment options will work.

Recovery time

It can take several weeks or even months for porokeratosis lesions to go away. Some treatments may cause the lesions to fade. But they may not completely disappear. Your healthcare provider will explain what to expect based on your specific treatment plan.

When should I see my healthcare provider?

Reach out to your healthcare provider if you notice porokeratosis symptoms. These may include skin color changes or growths. Schedule an appointment if lesions quickly change colors, grow or hurt.

What can I expect if I have porokeratosis?

It’s a chronic (long-term) condition that you’ll have throughout your life. There’s no cure. But treatment may help remove individual lesions or improve their symptoms or appearance.

Porokeratosis isn’t contagious. But it’s possible that you could pass the condition on to your biological children. If you have porokeratosis, talk to your primary care provider. They can let you know if it’s a good idea to talk to a genetic counselor.

Your outlook depends on what type you have. Some types affect more areas of skin than others or are more likely to appear during certain ages. Your healthcare provider will work with you to find the best treatment option.

Because some porokeratosis lesions can develop into skin cancer, it’s important to take extra steps to protect your skin. You can help reduce your risk by:

• Limiting sun exposure, especially between 10 a.m. and 4 p.m.
• Applying sunscreen with an SPF of at least 30 every time you go outside, even if it’s cloudy
• Reapplying sunscreen every two hours or after swimming or sweating
• Wearing protective clothing, wide-brimmed hats and UV-blocking sunglasses when you’re outside
• Avoiding tanning beds
• Scheduling regular appointments with your healthcare provider