Common skin lesions

Key points

1. Melanoma warning signs: Asymmetry, irregular Border, varied Colour, Diameter over 6 mm, Evolution.
2. Basal cell carcinoma: pearly nodule with rolled edges and telangiectasia; it rarely metastasises.
3. Squamous cell carcinoma: keratotic, often tender nodule on sun-damaged skin; it can metastasise.
4. Seborrhoeic keratosis: 'stuck-on' waxy plaque with keratin cysts; benign.
5. Actinic keratosis: rough scaly patch on sun-exposed skin; a precursor of squamous cell carcinoma.

Image guide

What to look for in each view of this topic.

1. Superficial spreading melanoma. Irregular border and several colours; the commonest melanoma subtype.
2. Nodular melanoma. Rapidly growing, often symmetrical nodule; may lack pigment.
3. Nodular basal cell carcinoma. Pearly papule with rolled border and surface vessels.
4. Squamous cell carcinoma. Keratotic nodule on the scalp of an older man with sun damage.
5. Seborrhoeic keratosis. Stuck-on appearance with comedo-like openings.
6. Keratoacanthoma. Rapidly growing dome with a keratin plug; treated like squamous cell carcinoma.