Skin Cancer & Precancer
Squamous Cell Carcinoma in Situ (Superficial)
Bowen's disease; SCC in situ
Common on sun-exposed skin
No — you cannot catch it or spread it
Yes — very high cure rate when treated
What Is It?
Squamous cell carcinoma in situ, also called Bowen's disease, is an early, surface-level skin cancer. The abnormal cells are confined to the top layer of skin and have not grown deeper. It looks like a red, scaly patch. A small percentage can, over time, become invasive, so it is treated or closely monitored.
Signs & Symptoms
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A red or pink, scaly, well-defined patch
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Often mistaken for eczema or psoriasis
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Slowly enlarges and does not fully heal
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May be slightly crusted or itchy
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Common on the lower legs, head, neck, and hands
Why Does It Happen?
It is caused mainly by long-term ultraviolet (UV) damage from the sun or tanning beds. Risk is higher with fair skin, older age, and a weakened immune system (for example, from immune-suppressing medicines). It is NOT contagious and NOT caused by poor hygiene.
Treatment Options
Because it is surface-level, this cancer can often be treated with creams, light therapy, or minor procedures. Treatment prevents it from becoming invasive.
TOPICAL CREAMS
5-fluorouracil or imiquimod applied over several weeks.
CRYOTHERAPY
Freezing the patch with liquid nitrogen for smaller lesions.
CURETTAGE & ELECTRODESICCATION
Scraping and sealing the area in the office.
PHOTODYNAMIC THERAPY
A light-activated medicine that clears surface lesions.
Tips for Managing It at Home
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Use broad-spectrum SPF 30+ sunscreen daily and reapply
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Wear protective clothing and seek shade at midday
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Do regular skin self-checks and note new scaly patches
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Expect treated skin to redden and crust before healing
When to Call Your Provider
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The patch grows, thickens, becomes lumpy, or forms a sore
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It bleeds, becomes tender, or won't heal
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A new scaly patch appears on sun-exposed skin
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You have not had a recent full-body skin check
Sources & further reading
The information in this handout is based on general dermatology guidance from the reputable organizations below. These links are provided for patients who wish to read more from trusted sources.
American Academy of Dermatology (AAD). Squamous Cell Carcinoma: Overview. https://www.aad.org/public/diseases/skin-cancer/types/common/scc
Canadian Dermatology Association (CDA). Squamous Cell Carcinoma. https://dermatology.ca/public-patients/diseases-conditions/skin-cancer/squamous-cell-carcinoma/
DermNet. Cutaneous SCC in situ (Bowen Disease). https://dermnetnz.org/topics/cutaneous-squamous-cell-carcinoma-in-situ
MSD/Merck Manual. Squamous Cell Carcinoma. https://www.msdmanuals.com/professional/dermatologic-disorders/cancers-of-the-skin/squamous-cell-carcinoma
This handout is for general education and does not replace advice from your own provider. Always follow your provider’s specific instructions.
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