Lichenoid Keratosis

Lichenoid keratosis is described as a small, inflamed macule or a thin pigmented plaque that appears solitary. It is also known as solitary lichen planus, benign lichenoid keratosis, and involuting lichenoid plaque. Lichenoid keratosis is one of the causes of atypical solar lentigo.

Lichenoid keratosis is predominant among fair-skinned individuals aged 30 to 80. Females are twice as likely to be affected as males.

Lichenoid keratosis is an inflammatory reaction that appears as a response to a regressing existing solar lentigo or seborrheic keratosis. The causes remain unknown; however, minor trauma, including sun exposure, dermatitis, drugs, and friction, can serve as triggering agents.

In cases of lichenoid keratosis, a solitary lesion is present 90% of the time. The upper trunk is affected the most, followed by the distal extremities, neck, and head. The size of the lesion ranges from a few millimetres to one centimetre. The skin surface can be either smooth, warty, or scaly. These lesions appear asymptomatic in most cases; however, some people report experiencing itchy or mild stinging sensations.

Lichenoid keratosis is usually diagnosed clinically and confirmed via dermatoscopy. A skin biopsy is required if it is difficult to differentiate between lichenoid keratosis and other solitary erythematous lesions at clinical examination.

Lichenoid keratosis can be removed if desired by electrosurgery, curettage, or liquid nitrogen.

For treating multiple eruptive lichenoid keratoses, oral retinoid can be used.