Bowen's Disease with a Small Skin Lesion (< 2 cm) When First-Line Treatment Has Not Achieved Clearance

Clinical scenario

This protocol addresses patients with squamous cell carcinoma in situ (Bowen's disease) presenting as a lesion smaller than 2 cm at a low-risk anatomical site — the trunk or limbs — in an immunocompetent individual. Lesions meeting this size and site profile may be suitable for management in primary care by a clinician capable of establishing a clinical diagnosis.

Previous treatment — goal not met

Standard first-line options for this scenario include:

Topical 5-fluorouracil (5%)
Curettage with cautery
Conventional photodynamic therapy
Standard surgical excision
Cryotherapy

This protocol applies when the above approaches have failed to achieve complete clearance of the SCC in situ lesion within 6 months — the defined goal of the first treatment line.

Next-step approach (partial overview)

When initial therapies have not achieved clearance, secondary options at low-risk sites involve either a topical immunomodulatory agent or a laser-based intervention, each suited to specific circumstances.

Full regimen details, selection criteria, and sequencing are in the structured protocol below.

Instant Access to Structured Evidence-Based Regimens

References

DOI: 10.1093/bjd/ljac042

Offer* cryotherapy as a first-line treatment option to people with small (< 2 cm) SCC in situ lesions (see R15).

Lesions are considered large if > 2 cm and are considered high risk at periocular and digital (and penile) sites.

SCC in situ that is small (< 2 cm) and at a low-risk site (such as the trunk and limbs) may be managed in primary care by a general practitioner who is capable of establishing a clinical diagnosis and initiating treatment options as per the guideline in the first instance.

Consider topical imiquimod (5%) in people with SCC in situ at low-risk sites, when there is no suitable alternative. Consider once-daily application, three times per week for 4 weeks, although prolonged treatment for 12 weeks may be required.

Where this service is available, consider laser treatment in people with SCC in situ where other treatments have failed or are not suitable. Ablative CO2 laser may be more effective than nonablative neodymium:YAG.

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