Lichenoid keratosis (syn. lichen planus-like keratosis)

A lichenoid keratosis is a common, benign and often solitary skin lesion.

This chapter is set out as follows:

• Lichenoid keratoses appear to result from the inflammatory destruction of a pre-existing epidermal lesion such as a solar lentigo or seborrhoeic keratosis

• Generally asymptomatic
• More common in Caucasians
• Predominantly affect adults
• Equal incidence in males and females

Distribution

• More common on UV-exposed areas, but can affect any part of the body

Morphology

• Usually solitary
  
• Generally less than 1 cm in diameter
• Flat or slightly elevated
• The surface tends to be smooth, although occasionally scaly or warty
• Lesions typically progress from an inflammatory phase, where there may be some pink-red discolouration, to a pigmented phase, where the lesion becomes grey-brown in colour

Dermoscopic appearance

• Grey dots uniformly distributed throughout the lesion 

• Lesions are benign, no treatment is required

• If the greys dots are not uniform and / or there are other atypical features, eg irregular pigmentation of hair follicles or an angulated network (sometimes referred to as rhomboid structures), then lentigo maligna should be suspected and the patient referred urgently (two-week wait)