Lichenoid keratosis is also known as Lichen Planus-like Keratosis (LPLK) that typically present as small, solitary (90% of cases), brown macule or papule that can turn red and itchy . There is often an inflammatory component to this lesion.
Lichenoid keratosis are most commonly seen in fair-skinned patients aged 30 to 80 years old with a predilection for women than men. Studies have shown that women have twice the chance of getting lichenoid keratosis.
Causes and Risk Factors
- The cause of lichenoid keratoisis is unknown but several triggers have been identified.
- Some known triggers include, trauma, rubbing frictional trauma, medications, UV exposure and skin inflammation.
Symptoms and Clinical Presentation
The surface of lichenoid keratosis often have variable feel from ranging from smooth, to scaly or warty. The size of the lesion can also be variable but usually small to slightly over 1 cm.
Lichenoid keratosis are solitary lesion in 90% of the cases and found on sun exposed areas. The clinical features of lichenoid keratosis vary depending on the inflammatory stage of the lesion.
Classic, bullous or atypical subtype:
- This lesion typically form more quickly, usually within 3 months. They present as pink to reddish plaque to papules.
Early or interface subtype:
- This lesions can persist for 3 to 12 months. They present as reddish brown to brown hyperpigmented papules or plaques. Dermatoscopy may show features of lentigo or flat seborrhoeic keratosis like lesion, often with a classic moth bitten border and comedo-like opening.
Late regressed or atrophic subtype
- This lesion may persist for more than 1 year, appearing as plaques with violet or brown/grey lesions that are usually asymmetrically distributed. This lesion is darker compared to the other 2 subtypes.
All of the above 3 subtypes of lichenoid keratosis may be distinguished under dermatoscopy.
- The diagnosis of lichenoid keratosis is based on clinical appearance and dermatoscopic appearance.
- Dermatoscopy reveals gray dots that arrange in uniform clusters. They may also show signs of original pre-existing lesion such as seborrhoeic keratosis (SK) and lentigo. With time, the pre-existing lesion gradually disappears, the gray dot disappear and the lesion evetually regress to expose the normal skin.
- Because of the difficulty in making a diagnosis via clinical appearance and dermatoscopy, biopsy may be indicated to rule out other solitary erythematous to violet lesions that could be other benign of malignant lesion.
Treatments and Managements
Lichenoid keratosis lesion are typically benign and usually regress spontaneously. Consecutive images are usually taken to follow the lesion for suspicious changes.
Most removal are for cosmetic reason via the following approach:
- Single lesions: Liquid nitrogen, electrosurgery or curettage.
- Multiple eruptive lesion can be treated with oral retinoid and acitretin.