The appearance of seborrhoeic keratoses is extremely diverse.
An SK is generally scaly and brown in colour (light to dark). The colour can vary from pink through to black, and they generally range in size from 1-3cm in diameter.
Initially, the lesion is flat, gradually becoming raised from the skin surface – by which time it appears ‘stuck on.’ The surface is dull, warty, or waxy.
The pink or light brown SKs are more likely to be dull, whilst the darker brown ones are typically waxy. You can see this in the gallery images.
The face and trunk are commonly affected areas however they can appear anywhere on the body. It is not uncommon to have multiple SKs.
Dermatoscopy of SK will show characteristic features, avoiding the need for a biopsy – but not always.
A pitfall is ‘melanoacanthomatous melanoma’ – in other words, a melanoma that looks like an SK.