melanoma

Other Common Skin Cancer

Other Common Skin Cancer


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  • - ILYA MUKOVOZOV
  • - M.D., PHD | PGY-3 DERMATOLOGY
  • - UNIVERSITY OF BRITISH COLUMBIA

PRECANCER AND EARLY CANCER CONDITIONS ACTINIC KERATOSIS AND BOWEN’S DISEASE

  • Actinic keratosis is a precancer and Bowen’s disease is an early skin cancer condition. They both have the potential to develop into a type of invasive skin cancer called squamous cell carcinoma
  • In actinic keratoses only part of the epidermis (often only the basal layer of the skin) is affected by cancerous cells, while in Bowen's disease all of epidermis is affected. The important point is that in Bowen’s disease cancerous cells are not trying to escape into the dermis (a deeper layer of the skin). This is why Bowen’s disease is called Squamous Cell Carcinoma “in situ”. When they do, it becomes a true invasive Squamous Cell Carcinoma.
  • Actinic keratosis and Bowen’s disease are the most common precancerous conditions of the skin
  • Actinic keratosis is much more common than Bowen’s disease
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ACTINIC KERATOSIS

  • Actinic keratoses (AKs) are most commonly found on fair-skinned persons but can be seen in all races
  • They appear as skin coloured, or pink, or red areas with rough scaly skin ranging from a few millimeters to ~1 centimeter in size
  • AKs occur on sun damaged skin on the head, neck, upper trunk and extremities
  • A clue to AKs is the presence of scaly areas with indistinct borders on sun damaged skin
  • AKs are so common that it is estimated that up to 12% of the population have them
  • AKs are a sign of an increased risk of developing SCC, although the rates of transformation of AK to SCC are low (estimated at 1/200 – 1/1000 chance per lesion per year). So, if you have ~10 AKs 1 of them may become cancerous over 10 years.
  • AK occurring on the lips (predominantly on the lower lip that “sees more sun”) is called actinic cheilitis
  • AKs may spontaneously regress and then recur at the same or nearby sites
  • Pigmented variants of AKs (with tan, brown or black colour) exist but are less common

RISKS FACTORS FOR ACTINIC KERATOSIS

  • Skin phototypes I and II
    (fair skin; skin types that burn easily and tan less than average)
  • Significant cumulative sun exposure (many years)
  • A history of previous actinic keratosis
  • Older age
  • Immunosuppression
  • Male gender

DIAGNOSIS OF ACTINIC KERATOSIS

  • Actinic keratoses (AKs) are usually diagnosed clinically without a biopsy
  • A clue to the diagnosis of AKs is their rough scaly texture (sand paper like sensation) on a background of normal or pink skin; they are often more easily felt than seen
  • If atypical features are present, or the lesion does not go away after treatment, or if a clinician is concerned about a particular lesion, a sample of skin may be obtained via a biopsy procedure in order to rule out other conditions such as squamous cell carcinoma

TREATMENT OF ACTINIC KERATOSIS

  • The treatment options for actinic keratosis depend on the number and location of lesions, with consideration for the individual’s skin type
  • Liquid nitrogen spray, or cryotherapy, is the most commonly used treatment modality for individual lesions. The problem with this approach is that you often only can treat the spots that are well developed. Consider our garden analogy, where you are plucking weeds individually by hand. You are only able to pluck the weeds that you can see. What about the ones that are there, but have not broken through the ground? To target these we use herbicide or a “field treatment approach”. It is the same for AKs. We estimate that for every AK we see there are 3-10 that we can’t see with a naked eye. But it does not mean that they are not there!
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  • Field therapy is a term when we treat an area of skin (for example when treating a larger area of skin such as the entire scalp or whole forehead). It is advantageous when there are extensive actinic keratoses covering a large area of the skin (for example on the forehead, temples, or bald scalp in heavily sun exposed individuals)
  • Field therapy has the advantage of treating the sub-clinical lesions (microscopic disease that is not visible by eye or detectable on clinical exam) located between clinically visible actinic keratoses
  • Individuals with darker skin phototypes (phototypes III-VII) have a high risk of post inflammatory pigmentation changes after treatment with cryotherapy, resulting in areas of lighter (post inflammatory hypopigmentation) or darker skin (post inflammatory hyperpigmentation) following treatment
  • Field therapies can be performed with immune modulating creams; for actinic keratoses these include
    • 5-fluorouracil (5-FU), Brand name: Efudex cream
    • Ingenol mebutate, Brand name: Picato
    • Imiquimod, Brand names: Aldara or Zyclara
  • Chemical peeling; field therapy for AKs
    • Given the superficial nature of actinic keratosis, chemical peels can be utilized as a field therapy
  • Photodynamic therapy; field therapy for AKs
    • Photodynamic therapy involves the application of a special photosensitizing cream followed by exposure to sunlight or artificial light in order to activate the cream and destroy abnormal cells in the superficial layer of the skin
  • Cryotherapy (with liquid nitrogen) and lasers can be applied to individual lesions or small groups of lesions

BOWEN’S DISEASE

  • Bowen’s disease is also known as squamous cell carcinoma in situ
  • The abnormal cells are confined to the epidermis or top layer of the skin
  • Bowen’s disease usually presents as a reddish scaly patch which is sometimes crusted. What makes it distinct from other red rashes is the irregular shape, which suggests that this is a cancer.
  • Most often seen on face, legs, backs of hands or fingers
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  • Bowen’s disease is an early form of squamous cell carcinoma in which the cancerous cells are limited to the outer layer of the skin
  • If left untreated, Bowen’s disease can spread to deeper layers of the skin and eventually become an invasive SCC with the potential for spread, or metastasis, to lymph nodes and distant organs
  • The patches in Bowen’s disease tend to be bigger, redder, and more scaly than actinic keratoses

RISK FACTORS FOR BOWEN’S DISEASE

  • Same risk factors as for actinic keratoses
  • Increasing age
  • Exposure to ultraviolet B radiation from the sun
  • Immunosuppression
  • Previous radiation therapy
  • Arsenic exposure
  • Infection with human papillomavirus

DIAGNOSIS OF BOWEN’S DISEASE

  • If signs and symptoms of Bowen’s disease are present, a sample of skin must be obtained via biopsy procedure in order to make a diagnosis (diagnosis requires a pathologist to review the skin specimen under a microscope)
  • The most common biopsy techniques are punch (small cylinder of tissue typically 3-6mm is obtained) and shave biopsy (superficial skin shaved with a blade)
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TREATMENT OF BOWEN’S DISEASE

  • The treatment options for Bowen’s disease depend on size and location of the lesion
  • Liquid nitrogen spray (also known as cryotherapy) is a commonly used treatment modality for small localized lesions
  • Field therapies can be performed with immune modulating creams; for Bowen’s disease these include:
    • Topical 5-fluorouracil (5-FU) cream, Brand name: Efudex
    • - Topical 5-FU cream can be used for treatment of Bowen’s disease
    • - A variety of creams and solutions available with different dosing regimens (e.g. 5% cream twice daily for 2-4 weeks)
    • - Healing usually occurs within 2 weeks of stopping treatment
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  • Imiquimod cream, Brand names: Aldara or Zyclara

    - Topical imiquimod 5% cream can be used for treatment of Bowen’s disease with clearance rates of 73-88%

    - May cause flu like symptoms in some individuals

    - Recommended treatment area is 25cm2 or less

  • Photodynamic therapy; field therapy for Bowen’s disease

    - Photodynamic therapy involves the application of a special photosensitizing cream followed by exposure to sunlight or artificial light in order to activate the cream and destroy abnormal cells in the superficial layer of the skin

  • Surgery
    • Surgical excision
    • Curettage and electrodesiccation
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