Bowen’s disease (SCC in situ)

Background and Epidemiology

  • Although commonly called SCC in situ, Bowen’s disease differs slightly in its aetiology and pathophysiology.  (AK is a truer representation of SCC in situ).
  • It is estimated to have an incidence of around 15/100000 per year but can be higher.
  • Unlike actinic keratosis, it is much more common in women

Pathophysiology/Histopathology

  • Similar to that of SCC and AK but (in contrast to AK) there is full thickness epidermal involvement (atypical keratinocytes) and mitotic figures can be present.
    • Bowen’s disease is also thought to have an inflammatory (as well as genetic) component
      • Quite often, there is accompanying inflammatory, mostly lymphocytic, infiltrate in the superficial dermis

Risk factors/Aetiology

  • Age
  • UV exposure
  • Other irradiation damage e.g. radiotherapy, photochemotherapy
  • Carcinogens e.g. arsenic (could be used as an ingredient in old ointments for psoriasis/asthma
  • There is a significant associated with the HPV virus (typically HPV-16)
  • Immunosuppression
  • Chronic skin injury/conditions e.g. seborrhoeic keratosis

Presentation

  • Slowly growing, usually solitary, patch/plaque with clearly defined borders, scaling/hyperkeratosis, and an erythematous (pink/red) surface.
    • Usually several centimetres in size.
    • Usually otherwise asymptomatic
    • Most commonly found on the lower limbs (shins are common).  Otherwise, the head/neck and upper limbs can be sites.
      • Occasionally, bowen’s disease may be found in areas not exposed to the sun e.g. sub-/peri-ungual, genital (on the penis this is known as Queyrat’s erythroplasia) or perianal
  • Under the dermatoscope:
    • Characterised by scaly surface and glomerularly arranged vessels (clustering throughout the lesion)

Investigations

  • Skin biopsy should be taken for the definitive diagnosis

Management

  • In contract to SCC and AK, topical therapy e.g. topical 5-fluorouracil (first line) or imiquimod treatments are preferred.
  • Cryotherapy may be used as an alternative, particularly in smaller lesions
  • Other managements e.g. surgery/curettage and PDT can also be used (the latter particularly for immunosuppressed patients; the former may be suitable for small lesions)
  • Radiotherapy can be used if the area is unsuitable for other treatment options

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