In short. Bowen disease is squamous cell carcinoma confined to the epidermis. Why it is treated rather than watched, and how excision, curettage and topical treatments compare.
Key points
- Patients often hear in situ and conclude that nothing needs doing.
- In situ describes the present, not the future.
- It means the cancer has not yet invaded, which makes treatment simpler, more reliable and more often curative.
Bowen disease is a persistent red, scaly plaque that is often mistaken for eczema, psoriasis or a fungal infection. Its other name states precisely what it is: squamous cell carcinoma in situ. The atypical cells fill the full thickness of the epidermis, but the basement membrane beneath them is intact, so the tumour has not yet acquired the ability to invade or to spread. That is a favourable position to be in — and one worth acting on.
What it looks like
A typical lesion is a slowly enlarging, well-defined red patch with scaling or crusting, sometimes several centimetres across, often on the lower leg, head, neck or trunk. It grows over months to years and does not settle. Because it does not look alarming, it is frequently treated for a long time as something else before a biopsy establishes the diagnosis. Any persistent scaly patch that does not respond to ordinary treatment deserves a sample.
Why it should be treated
Untreated, a proportion of Bowen disease progresses to invasive squamous cell carcinoma. Estimates vary, but a meaningful minority do, and the risk is higher for lesions that are large, long-standing, on the lip or genital skin, or in people who are immunosuppressed. Progression removes the most valuable property the lesion had: it was contained. It also changes the operation from a straightforward excision into one that must address depth, margins and, in some cases, lymph nodes.
In situ is not harmless
Patients often hear in situ and conclude that nothing needs doing. In situ describes the present, not the future. It means the cancer has not yet invaded, which makes treatment simpler, more reliable and more often curative. The reasonable choice is to treat it while that remains true, rather than to observe it until it is no longer in situ.
Treatment options
Surgical excision with a measured margin is the most reliable treatment, because it removes the lesion and allows the pathologist to confirm that the margins are clear. Curettage with cautery suits smaller, superficial lesions on suitable sites. Cryotherapy is used for small lesions but yields no tissue for margin assessment. Topical field therapy and light-based treatment can clear large or multiple lesions, and are useful where surgery would be disfiguring or where lesions are widespread, at the cost of a longer course and no specimen to examine. Radiotherapy is occasionally chosen for patients who cannot undergo surgery.
After treatment
Healing depends on the method and the site: an excision heals as a scar over one to two weeks, while field treatment may take several weeks to settle. Recurrence is uncommon after complete excision but not impossible, so review is advisable for at least a few years. Because Bowen disease reflects cumulative ultraviolet damage, a second lesion elsewhere is a realistic possibility, and skin surveillance should continue.
Seek review promptly if
- A treated area develops a new lump, ulceration or bleeding rather than settling into a scar.
- A persistent red scaly patch enlarges, thickens, or becomes painful or tender.
- A lesion previously called Bowen disease recurs at the same site after treatment.
Frequently asked questions
Why is Bowen disease treated rather than simply observed?
Untreated, a proportion of Bowen disease progresses to invasive squamous cell carcinoma. Progression removes the most valuable property the lesion had, which is that it was contained, and changes a straightforward excision into an operation that must address depth, margins and sometimes lymph nodes.
Why is surgical excision often preferred over cryotherapy?
Excision with a measured margin removes the lesion and allows the pathologist to confirm that the margins are clear. Cryotherapy is used for small lesions but yields no tissue for margin assessment, so it cannot give that confirmation.
What does in situ actually mean?
It describes the present, not the future. In situ means the atypical cells fill the full thickness of the epidermis while the basement membrane beneath them is intact, so the tumour has not yet acquired the ability to invade or to spread.
Risks & Limitations
- Incomplete excision, which may require a further operation to achieve clear margins.
- Recurrence of the skin cancer, and the need for surveillance for years afterwards.
- Scars are permanent. They mature and fade but never disappear.
- Problems with a graft or flap, including partial or complete loss, which may need further surgery.
- Numbness, altered sensation or nerve injury around the operated area.
- Melanoma carries a risk of spread that surgery cannot remove, even when the excision is complete.
- Pigment change, contour irregularity, or a scar that widens or thickens.
- Final assessment of the scar is made at 6–12 months, and surveillance continues longer.
When to Seek Care
- A lesion that changes in size, shape, colour or height, or that starts to bleed or itch.
- A new, rapidly growing nodule, or a sore that is not healing.
- A mole that becomes painful or bleeds.
- Swelling in a lymph node region — the neck, armpit or groin.
- A graft or flap that turns dark, cold or black, or a wound that opens or discharges.
- Fever above 38 °C, or spreading redness, warmth or pain around a wound.
References & Further Reading
- American Academy of Dermatology (AAD) — skin cancer diagnosis and treatment guidance
- American Cancer Society (ACS) — skin cancer types, staging and outlook
- Skin Cancer Foundation — prevention and skin self-examination resources
- American Society of Plastic Surgeons (ASPS) — reconstruction after skin cancer excision
- Cochrane Library — systematic reviews in skin cancer treatment and prevention
- Chinese Medical Association — clinical guidance for skin tumours and dermatologic surgery
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.