Lichen Planus
Like Keratosis.
LPLK describes inflammation in a benign skin lesion.
LPLK
LPLK can be thought of as a lesion covered by a ‘veil’ that may hide the nature of the lesion. Biopsy is often required to confirm the diagnosis.
Lichen Planus
What is LPLK?
LPLKs make the forest thicker when trying to find the wood.
LPLK is short for Lichen Planus like Keratosis, also called Lichenoid Keratosis. LPLK is common in sun-exposed areas and very common in Australia as a result of UV exposure.
LPLK is an inflammatory reaction and often occurs in a pre-existing skin lesion that is something else. This type of “Lichenoid Reaction” is common in a Seborrhoeic Keratosis (Seb K) or solar lentigo.
Who gets them?
LPLK is very common in fair-skinned people over the age of 30.
Anyone with a seborrhoeic keratosis or solar Lentigo can get this reaction.
What are the clinical features?
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.
Gallery of LPLK
Please click on the images for details.
Treatment for LPLK
The natural course of LPLK is for it to eventually fade as it moves from the inflammatory to the burnt-out phase. An isolated lichenoid keratosis that is very long-standing is often very difficult to see. In other words, the lesion usually treats itself!
If the lesion is a cosmetic concern, it can be removed if desired by liquid nitrogen, electrosurgery or cutterage.
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