Bowen's Disease with a Large Lesion (>2 cm) at a Low-Risk Site After First-Line Treatment Has Not Achieved Clearance
This clinical situation involves squamous cell carcinoma in situ (Bowen's disease) presenting as a lesion larger than 2 cm at a low-risk anatomical site — trunk or limbs — in an immunocompetent patient whose first-line treatment has not cleared the lesion.
Clinical Scenario
The lesion is classified as large (greater than 2 cm) and is situated at a low-risk site (trunk or limbs). The patient is not immunosuppressed. Lesion size is a key factor in treatment selection: lesions above 2 cm carry specific management considerations distinct from smaller Bowen's disease lesions.
First-Line Therapy: Goal Not Met
This protocol applies when the previous treatment — conventional photodynamic therapy (red-light) or topical 5-fluorouracil (5%) — did not achieve complete clearance of the SCC in situ lesion within 6 months. The protocol below defines the structured next step for this specific failure condition.
Second-Line Approach (Partial Overview)
Several secondary options are available for this scenario, spanning both procedural interventions and topical therapies. Selection among them depends on individual patient and lesion factors. The full structured regimen — including which option applies and under what circumstances — is available in the complete protocol.
References
DOI: 10.1093/bjd/ljac042
- Lesions are considered large if > 2 cm and are considered high risk at periocular and digital (and penile) sites.
- Consider curettage with cautery on an individual basis in people with SCC in situ with larger lesions. Consider patient factors (age, location, skin health) and discuss the risk of prolonged healing and potential ulceration.
- Consider cryotherapy on an individual basis, in people with SCC in situ with larger lesions, and those on the lower leg (see R15).
- Offer* standard surgical excision to people with SCC in situ where morbidity from surgery is low, or for recurrent or refractory disease. Use an appropriate clinical margin to achieve complete clearance. Depending on the anatomical location and clinical assessment, a 3–5-mm margin may be preferable (see Appendix C).
- 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.
- Refer* immunocompetent people with SCC in situ for consideration for radiotherapy only where the lesion is recurrent or refractory to other treatments, or where surgery is not appropriate or is associated with high morbidity.
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