Bowen’s disease is a form of SCC in situ. Bowen’s are well demarcated, erythematous hyperkeratotic plaques with irregular borders, characterized by full-thickness epidermal dysplasia on histology. They occur more in females and those in there 70s. The majority of studies report that SCC in situ occurs mainly on sun-exposed sites, with more recent studies suggesting the most common site being the head and neck. However, the lower limbs seem to be affected more in women than in men. Less common variants include pigmented, subungual, periungual, palmar, genital, perianal and verrucous SCC in situ.
If there is any diagnostic doubt, or if confirmation is required before proceeding with a certain type of treatment, a punch biopsy should be carried out. This is preferable to a curette biopsy, as the full thickness of the epidermis and dermis can be viewed to establish whether there is any invasive disease amounting to a cutaneous SCC.
Risk associated with Bowen’s Disease
Some studies have shown 30–50% of subjects with Bowen’s disease either already have a NMSC or go on to develop another non melanoma skin cancer (NMSC). These are mainly basal cell carcinoma (BCC). This is thought to be related to a common solar aetiology. Overall most studies show Bowen’s has an invasive risk of 3-5%.
Treatment options include topical 5-flurouracil, topical imiquimod, cryotherapy, curettage, excision, PDT, radiotherapy and laser. The choice of treatment depends on the size and anatomical site.
BAD report the difficulties of evaluating studies surrounding treatment of Bowen’s This is partly to do with data collection, as there are cases where treatment is being given without a biopsy which makes it difficult to compare treatment modalities. Added to this caveat is that treatment of varying anatomical sites has an effect on treatment clearance. Which means there is often selection bias in relation to certain forms of treatment.
Therefore treating Bowens effectively requires appreciation of anatomical sites, varying treatment and clearance likelihood alongside patient counselling. (15)