LPLK tends to occur in areas that are exposed to the sun, such as the forearm, lower leg and face.
The lesions are usually solitary and less than 1cm in diameter. They are usually flat or can be slightly elevated with a smooth surface.
LPLK can be thought of as a ‘regressing’ seborrhoeic keratosis (SK) or solar lentigo. So you first need to know what an SK or Solar Lentio looks like. In the inflammatory phase, LPLK is usually somewhat pink or red. In the ‘burnt-out’ phase, LPLK is typically grey or greyish-brown.
The term “lichenoid reaction” is often used by the pathologist. The pathology will determine whether the LPLK has derived from a solar lentigo or seborrhoeic keratosis.
LPLK tends to be identified at a skin check for one of two reasons
- A Seborrhoeic keratosis or age spot has developed a lichenoid reaction. It’s usually possible to identify the lesion as ‘having been’ an SK or age spot and to identify changes of LPLK on dermoscopy.
- Longstanding LPLK is a <1cm patch of pale grey colour skin. The diagnosis is normally confirmed with dermoscopy.
This condition can look similar to skin cancers such as IEC and lentigo maligna.