What is lichenoid keratosis?
Lichenoid keratosis is usually a solitary lesion that looks similar to a lentigo, Bowen disease (in situ squamous cell carcinoma), or superficial basal cell carcinoma. Histopathology (the microscopic structure and changes of the lesion) resembles that of lichen planus with some slight differences. The lesions appear to develop from a regressing existing lesion such as a lentigo or seborrhoeic keratosis as on close examination remnants of these former lesions may be evident.
Lichenoid keratosis is also known as benign lichenoid keratosis, solitary lichen planus, lichen planus-like keratosis and involuting lichenoid plaque.
Who gets lichenoid keratosis?
Lichenoid keratosis is an uncommon lesion with most cases usually discovered by doctors performing careful skin examinations. Most lesions develop in patients aged between 30-80 years and affect females more than males by 2:1. The condition is most commonly seen in Caucasians and rarely affects Asians, African Americans or Hispanics.
What are the clinical features of lichenoid keratosis?
The clinical features of lichenoid keratosis vary somewhat in relation to their histopathological findings and how long they have been present. These attributes have been used to define several clinical subtypes of lichenoid keratosis.
|Classic, bullous or atypical subtype|
|Early or interface subtype|
|Late regressed or atrophic subtype|
Other features of lichenoid keratosis found in all subtypes are:
- Solitary lesion is present in 90% of cases of lichenoid keratosis. A small number (<10%) of patients develop 2 or 3 lesions.
- Lesion most commonly found on the upper trunk, followed by the distal upper extremities, and less commonly on the head and neck.
- Lesion ranges from a few millimetres to one centimetre or more in size.
- Surface may be smooth, scaly or warty.
- Often symptomless or may be slightly itchy or have mild stinging sensation.
What is the management of lichenoid keratosis?
Initially the lesion is examined using dermoscopy. For lesions that are considered low-risk dermoscopic images can be taken and used in follow-up sessions over time to check for any significant changes.
Because clinical examination and dermoscopy may not be able to differentiate between lichenoid keratosis and other solitary erythematous lesions that could be melanocytic, non-melanocytic benign, malignant or inflammatory, a skin biopsy may be necessary to confirm diagnosis of suspicious lesions. Complete excision rather than an incisional biopsy is recommended.
Once the diagnosis of lichenoid keratosis is confirmed, the patient should be advised about the benign nature of the lesion and offered medical or surgical treatment to remove any remaining lesion. This may be treatment with liquid nitrogen, electrosurgery or curettage. In some cases the remaining lesion can be left alone.
To date there have been no reports of lichenoid keratosis turning into malignant skin tumours.