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Teledermatology for suspected skin cancers

Clinical features of skin lesions

Created 2017.

miiskin 3 2 133

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Text: Miiskin

Skin cancers and precursor lesions should be identified and removed.

  • Melanoma and melanoma in situ
  • Squamous cell carcinoma, intraepidermal carcinoma and actinic keratoses (where practical)
  • Basal cell carcinoma

Benign skin lesions should be identified. They don’t need removal, unless:

  • They appear suspicious for skin cancer
  • They are causing symptoms
  • The patient requests removal and accepts the consequences (eg scar)

General characteristics of skin cancer are:

  • Enlarging or changing over time (weeks to years)
  • Irregular in shape, surface, colour, structure
  • May bleed or ulcerate without injury

General characteristics of benign skin lesions are:

  • Stable  
  • Uniform in surface, colour, structure
  • Often symmetrical in shape
  • Any bleeding or ulceration is due to recent injury 

Melanoma

  • ABCDE characteristics
    • Asymmetry, Border irregularity, Colour variation, Diameter > 6 mm (or Different), Evolving
    • Typical of superficial forms of melanoma
    • Not always present, especially in nodular melanoma
  • Glasgow 7-point checklist

Major features:

  • Change in size
  • Irregular shape
  • Irregular colour

Minor features:

  • Diameter >7mm
  • Inflammation
  • Oozing
  • Change in sensation
    • Useful for invasive melanoma
    • May miss in-situ melanoma
  • A changing/enlarging lesion
    • This may or may not be observed
    • Benign lesions can change
  • Asymmetrical/irregular/variable colour, structure, surface
  • Shape is often irregular
    • Sometimes, melanoma is round
  • Size is often > 6 mm
    • Melanoma can be diagnosed when much smaller
  • Even experts miss some cases of melanoma
    • They can look similar to other lesions, especially seborrhoeic keratoses, solar lentigines and benign naevi
    • Be vigilant!

When evaluating pigmented lesions, especially if of concern to the patient, explain that diagnosis can be difficult:

  • Early melanoma often looks the same as a mole or freckle.
  • Most lesions that concern patients are entirely harmless.
  • Self skin examination is useful.
  • Any changing lesion, including any evaluated on this occasion, is worth showing to your doctor.
  • If the patient is concerned for any reason, return for re-evaluation.
  • A second opinion can be obtained using Teledermatoscopy.
  • The lesion could be excised for pathological examination.

Most melanomas arise from normal skin. Precursor lesions include:

  • Melanocytic naevus: any kind.
  • Giant congenital melanocytic naevi > 40 cm diameter.
  • Atypical lentiginous hyperplasia and atypical junctional naevus of the elderly. These are irregular pigmented patches in sun damaged skin of face, neck, upper trunk but clinical/dermatoscopic/histopathological characteristics do not meet criteria for diagnosis of melanoma.  

If the lesion is likely benign, explain reasons against unnecessary excision:

  • Unnecessary expense.
  • Unnecessary scar.
  • Unnecessary risk of complications eg infection, haemorrhage, delayed wound healing, drug allergy.
  • Pathological diagnosis can also be uncertain or incorrect.
  • Patient has other similar lesions that are not concerning to the patient or to their doctor.

Also explain the reasons that partial biopsy is generally avoided.

  • Melanoma can be focal within a skin lesion and partial biopsy may miss it.
  • Pathological diagnosis is very difficult and the pathologist needs a large sample to be confident.
  • Biopsy result can be misleading.

Invasive squamous cell carcinoma

  • Grows over weeks to months.
  • Tender, painful plaque or nodule.
  • It has a dermal component. Palpation often detects a rubbery component within the skin.
  • Well-differentiated SCC is scaly, warty.
  • Undifferentiated or anaplastic SCC may be difficult to distinguish from other epithelial cancers or even from melanoma histologically.
  • These lesions often present as nonspecific enlarging ulcers or ulcerated irregular plaques.

Precursor lesions are actinic keratoses and intraepidermal carcinoma for SCC.

Basal cell carcinoma

  • Grows over months to decades
  • Early bleeding and ulceration
  • Pearly nodule, plaque or edge
  • May be skin coloured or pink
  • Superficial BCC is an irregular plaque with small erosions and light scale

There is no precursor lesion for BCC.

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