Lichenoid Keratosis

Lichenoid keratosis is an uncommon, benign skin condition, which typically consists of a single lesion, usually on the upper torso and the distal upper extremeties, but in some cases may appear on the head or neck. Lichenoid keratosis is divided into subtypes which are predicated on the appearance of the lesion.

In the classic, bullous or atypical subtype, lesions typically form quickly (within 3 months), and present as red or pinkish plaques or papules. Early or interface subtype lesions present as red to brown hyperpigmentated papules or plaques. Late regressed or atrophic lesions may consist of papules which are violet in color or brown/grey lesions which are typically asymmetrically distributed. All subtypes may be distinguished under dermoscopy. Additionally, lichenoid keratosis is not typically accompanied by symptoms other than lesions, but affected persons may experience mild itching or stinging. Surface of the lesions may range from smooth, to scaly or warty, and may be anywhere from very small to over 1 cm.

Lichenoid keratosis is thought to be caused when lesions from existing skin conditions, such as lentigo or seborrhoeic keratosis, regress. Women are twice as likely to develop the condition, and it almost predominantly affects caucasians, though it may in rare cases appear in other ethnicities. Lesions from the disease typically appear between 30 and 80 years of age.

Differential Diagnosis (Other conditions with similar appearance)
Lentigo
Bowen disease
Basal cell carcinoma
Melanoma

Lichenoid keratosis is diagnosed based on the appearance of the affected area. This is typically done under dermoscopy. A skin biopsy will be performed to confirm the diagnosis and rule out similar appearing conditions.