Squamous cell carcinoma (SCC) in situ, formerly called Bowen disease, is an early form of skin cancer. This means the cancer cells are still limited to the epidermis (top layer of skin) and haven’t grown deeper yet.

Even though SCC in situ is an early-stage form of cancer, getting timely diagnosis and treatment still matters. Without treatment, there’s a chance that SCC in situ disease will grow into invasive squamous cell carcinoma and spread.

In this article, we’ll cover the basics: what SCC in situ looks and feels like, who gets it, how it’s diagnosed and treated, and its outlook.

What Is Bowen Disease?

SCC in situ is a slow-growing skin cancer. “In situ” means “in place.”

In Bowen disease, abnormal cells are found only in the epidermis, the outermost layer of skin. They have not yet invaded deeper layers.

That’s why it’s considered an early stage of squamous cell carcinoma. If treated early, it’s usually very manageable. If left untreated, it can become invasive and, rarely, spread.

Bowen Disease on Different Skin Tones

The appearance of squamous cell carcinoma in situ can vary depending on your skin color. On lighter skin, it’s often pink or red. On medium skin tones, it may look reddish-brown. On darker skin, it may appear darker brown, gray, or even slightly purple.

SCC in situ can sometimes be missed or mistaken for another skin condition because of its variable presentations.

Where Does It Appear?

SCC in situ can develop anywhere, but it most often appears on parts of the body exposed to the sun. For example, it can appear on the:

• Lower legs (most common location)
• Face, neck, scalp, or ears
• Hands or feet
• Arms

However, it also occurs on areas less often exposed to the sun, including the trunk, the genital area, or around the fingernails, where it may be related to the HPV virus.

There’s usually only one lesion, but up to 1 in 5 people may have multiple lesions at once.

Diagnosis of Bowen Disease

Diagnosis usually starts with a skin exam.

During a skin check, a dermatologist will look closely at the lesion with a dermatoscope. They will ask questions about how long it’s been there and how it’s changed over time.

Because SCC in situ can look like other conditions, a biopsy is needed to make a final diagnosis. In a skin biopsy, a small piece of skin is removed and examined under a microscope. This can help confirm whether abnormal cells are limited to the epidermis.

Bowen Disease Treatment Options

Treatment of squamous cell carcinoma in situ aims to remove or destroy the abnormal cells before they become invasive.

The best treatment option for you depends on:

• Size and location of the lesion
• Your overall health
• Personal preferences

Common Treatments

There are a number of treatments for SCC in situ. These include:

• Watch and wait — Your doctor may recommend watching the lesion over time rather than treating it right away.
• Cryotherapy (freezing) — Liquid nitrogen can freeze the lesion, and the skin peels off as it heals.
• Topical medications — 5-fluorouracil (5-FU) and imiquimod cream can be applied to the skin to destroy abnormal cells over time.
• Curettage and electrodessication — The lesion can be manually scraped off and heated to stop bleeding and kill remaining cells.
• Surgical excision — The lesion can be cut out completely to ensure no abnormal cells remain, especially if there’s fear that the skin cancer is invasive.
• Photodynamic therapy — A light-sensitive medication can be applied before light activates it to destroy cancer cells.

What’s the Prognosis?

The prognosis (outlook) for SCC in situ generally very good, especially with treatment.

If untreated, it turns into invasive squamous cell carcinoma in 3 percent to 5 percent of people.

If it becomes invasive, treatment becomes more complex, and there’s a higher risk of spread. Outcomes in these cases may not be as favorable as if it’s treated early. Early diagnosis and treatment offer the best chance of a full cure.

Progression Risk Factors

There’s a higher risk of progression with certain factors, including:

• Older age
• Weakened immune system
• Larger or long-standing lesions
• Previous history of skin cancer

Recurrence

Even after treatment, SCC in situ can come back in the same area. That’s why follow-up care is important.

Protecting Your Skin Going Forward

After a diagnosis of SCC in situ, protecting your skin from the sun becomes even more important.

Tips to prevent sun damage include:

• Using broad-spectrum sunscreen over sun-exposed areas
• Wearing protective clothing such as hats and long sleeves
• Avoiding going outside when the sun is most intense
• Seeking shade when possible

It’s important to stay aware of your skin to assess for new or changing spots. Pay close attention to areas that don’t heal, and contact your doctor if you notice anything new or unusual.

Following your dermatologist’s treatment plan, keeping up with regular skin checks, and protecting your skin from the sun can all help lower your risk of future problems.

When To Reach Out to Your Doctor

Reach out to your dermatologist if you notice:

• A scaly patch or crusted lesion that doesn’t heal or keeps growing
• A patch of skin that changes in color, size, or texture
• Bleeding or persistent irritation

These signs don’t always mean cancer, but they should be checked out by a healthcare professional.

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Have you or a loved one been diagnosed with SCC in situ? Let others know in a comment below.