Synopsis
Recognise cutaneous squamous-cell carcinoma in situ, distinguish it from eczema, psoriasis and invasive SCC, secure histology when needed and select treatment by site, lesion and patient factors.
- Bowen disease is SCC in situ: a persistent, slowly enlarging, well-demarcated scaly or crusted plaque, commonly on sun-exposed lower legs.
- Colour may be pink-red, violaceous or brown and is less reliable than persistent single-site scale and edge definition across skin tones.
- Biopsy when diagnosis is uncertain and whenever pain, induration, ulceration, bleeding or treatment resistance suggests invasion.
- Treatment options include excision, curettage and cautery, cryotherapy, photodynamic therapy and topical 5-fluorouracil; imiquimod is often off label.
- Choice depends on size, site, number, border, circulation, healing capacity, immune state, pathology and patient preference.
- Lower-leg lesions require vascular and oedema assessment because destructive or surgical wounds may heal slowly.
- A genital or periungual lesion needs specialist assessment for HPV association, functional anatomy and alternative malignancy.
- After treatment, review for clinical clearance and biopsy a persistent thick or ulcerated focus instead of repeating empirical therapy.
Key red flags
New induration, nodule, tenderness, ulceration, bleeding, rapid growth, failure after appropriate treatment, lip or genital site, immune suppression or palpable nodes raises invasive SCC and requires urgent specialist biopsy.
A new firm nodule, pain, ulcer, spontaneous bleeding or rapid growth within the plaque suggests SCC invasion.
Investigation priorities
Confirm full-thickness epidermal dysplasia and assess possible invasion.
Management branches
Histology or confident specialist assessment confirms Bowen disease without invasive warning.
- Assess size, site, border, circulation, healing, immune state and the patient’s priorities.
- Choose excision, curettage, cryotherapy, photodynamic therapy or a mapped topical course according to local expertise.
- Review after healing for complete clinical clearance and provide long-term skin-cancer awareness advice.
Key medicines
Fluorouracil 5% creamApply a thin layer once or twice daily to the precisely mapped lesion for three to four weeks or according to specialist site-specific instructions.Avoid pregnancy, eyes and mucosa; expected inflammation can be severe, and induration, infection, excessive ulceration or non-response requires review rather than automatic extension.