Bowen's disease

Bowen's disease is an intra-epidermal squamous cell carcinoma of the skin - full thickness of the epidermis is dysplastic with atypical keratinocytes, but these have not yet breached the basement membrane to become a squamous cell carcinoma:

• incidence is about 15 per 100,000 people in the UK
  
  
• the lesions of Bowen's disease are slow-growing, erythematous scaly pink skin plaques that cause few, if any, symptoms
  • in this condition there are features of malignant change within squamous cells e.g. excess and abnormal mitotic figures, and lack of squamous differentiation; however there is an intact basal membrane
  • if left untreated, Bowen's disease will progress to invasive squamous cell carcinoma in 3-5% of patients
    • note though that a 2017 study suggested that it may be much higher, with 16.3% of 566 cases of biopsy-proven Bowen’s disease found to have squamous cell carcinoma when treated surgically(2)

Clinically this condition is characterized by a slowly expanding pink, scaly plaque that has a sharply defined border. The lesion may be covered with crusts, which when removed reveal an oozy, papilliferous surface.The lesions of Bowen's disease are usually solitary and, in general, have a diameter of less than 5cm at diagnosis.

• mean age at which lesions begin to develop is around 60-70 years
• about three-quarters of people with the disease are women and most lesions occur on sun-exposed areas (e.g. head and neck, and lower leg in women), indicative of a relationship with chronic sun damage - note though that Bowen's disease can occur on any part of the skin, including the vulva - longstanding lesions can attain more than 2 cm in size through lateral spread (2)
  • other risk factors include:
    • exposure to ultraviolet light (ultraviolet)
    • immunosuppression
    • exposure to carcinogens
  • lesions are generally 10-15 mm in diameter and are slowly growing
  • in keeping with this, around a third of patients with Bowen's disease have had, or will develop, other skin pre-malignancies or malignancies, mainly basal cell carcinoma, actinic keratoses or squamous cell carcinom
  • incidence of non-melanoma skin cancer in patients with Bowen's disease is increased by about a factor of x4 (from about 3 to about 13 cases per 1000 patient-years)
  • there is no evidence of an association between an increased risk of internal malignancies and Bowen's disease

Click here for an example image of this condition

The differential diagnosis of Bowen's disease includes:

• actinic keratosis
• basal cell carcinoma
• squamous cell carcinoma
• seborrhoeic keratosis
• psoriasis
• eczema

Management:

• seek specialist advice
  
  
• a provisional diagnosis can be made on clinical grounds - however definitive diagnosis requires histological examination, and this is especially important if there are atypical features, if the lesion is thicker or larger than usual (suggesting that malignant change might already have occurred), or if it does not respond to treatment as expected
  • samples for histology may be obtained by excision, by punch biopsies, or by an incisional biopsy (from the clinically thickest area if the morphology of the lesion varies, in order to exclude invasive carcinoma)
  • note that since other skin malignancies may co-exist with Bowen's disease and therefore the rest of the skin, especially sun-exposed areas, should also be examined
    
    
• management options include watchful waiting, topical fluorouracil, cryotherapy, curettage, excision, laser, radiotherapy and photodynamic therapy - consider excision for solitary plaques of <= 15 mm diameter (2)
  • no one type of treatment appears to be superior for all clinical situations (2)
  • treatment should depend on various factors including the site and number of the lesions, treatment-related morbidity, costs and availability of the treatment options (2)
  • curettage and excision are cheapest and both are suitable for small single lesions; curettage may be preferable at poorly healing sites, such as the lower leg
  • cryotherapy may also be used for small lesions (single or multiple) where healing is good - however unwanted effects (e.g. blistering, discomfort at treatment site) limit its use (4)
    • a single freeze-thaw cycle with liquid nitrogen for 20-30 seconds - avoid in the gaiter area of the leg and other areas of poor skin healing. For larger patches treatment may be better tolerated if half of the lesion is treated initially and the other half six weeks later
  • photodynamic therapy may be used for large lesions, even at poorly healing sites
  • topical fluorouracil can be used for large or multiple lesions, even in areas that heal poorly, but it commonly causes unwanted effects (e.g. erosion, ulceration, severe eczematous reactions, and also may leave severe scarring at treatment site)
    • can be used once a night for four weeks. Hands should be washed thoroughly after application. The treated area must be left uncovered and washed the following morning. Warn the patient to expect some redness, crusting and mild discomfort. After four weeks stop the treatment and use a mild topical steroid eg 1% Hydrocortisone or Eumovate ® cream BD for two to four weeks to help settle down any inflammation (4)
  • topical imquimod has been shown to be effective in the treatment of Bowen's disease (3)
  • laser treatment may be used for lesions on the digits

follow-up

• patients should be followed up at three months
  • the presence of any remaining rough scale would suggest that the lesion has not fully responsed to treatment and that more is required, whereas the presence of smooth skin, sometimes with associated post-inflammatory hyperpigmentation (especially on the lower legs), suggests that the lesion has responded well, in which case further follow-up is not required (4)

Reference:

1. The Practitioner 1998; 242: 270-77.
2. Mohandes P et al. Bowen’s disease. BMJ 2020;368:m813
3. The Practitioner 2005; 249:398-407.
4. Primary Care Dermatological Society. Bowen's disease (Accessed 7/4/2020)