Seborrheic Keratosis



One of the most common and often misunderstood conditions is seborrheic keratosis.

Today, I want to demystify this skin condition by explaining in a clear and simple manner what it is, why it appears, how it can be treated, and most importantly, how it affects (or does not affect) our daily lives.


It is a type of benign skin growth, that is, non-cancerous. It appears as a skin lesion varying in colour tone from light brown, dark, or even black. It generally has a rough texture, as if it were "stuck" on the surface of the skin. Although they can appear anywhere on the body, they are most frequently found on the head, neck, and torso.


Evidence suggests a combination of genetic factors (family inheritance) and sun exposure.

It is not contagious, nor is it a result of poor hygiene (as some people think).


The main warning sign is the appearance of these skin lesions with distinctive characteristics. They can vary in size from a few millimetres to several centimetres, and although they are usually painless, they can cause irritation/inflammation if there is friction, and even cosmetic discomfort.

The diagnosis is made through a physical examination with the support of a dermatoscope, and in doubtful cases, a biopsy can be performed to confirm the diagnosis.


Although seborrheic keratosis is benign, its appearance can easily be confused with more serious skin lesions, such as melanomas, basal cell carcinomas, or squamous cell carcinomas, which are forms of skin cancer.

Differential diagnosis is a key process in dermatology that allows distinguishing between various types of skin lesions.

At first glance, some seborrheic keratoses may seem similar to conditions of greater severity. Therefore, it is essential that any treatment, especially ablative methods, which involve the elimination or destruction of lesions, should only be carried out after an accurate and confirmed diagnosis by a dermatologist.

Ablative treatments performed without a correct diagnosis, are not only, potentially dangerous, but can also mask or alter the characteristics of more serious lesions, complicating a future diagnosis.


Treatment is not always necessary from a medical standpoint, but many people choose to remove seborrheic keratoses for comfort or cosmetic reasons.

There are several treatment options:
     1. Cryotherapy: a quick method that uses liquid nitrogen to freeze and eliminate the lesions.
     2. Curettage: involves scraping the lesion off the skin.
     3. CO2 Laser: a quick and effective method in the healing process and offers superior aesthetic results.


Although there is no definitive strategy to prevent the appearance of seborrheic keratoses, since the main cause is often genetic.

Adequate sun protection and a regular skin care routine are recommended to maintain overall skin health.

Body moisturisers with urea in low concentrations (<10%) can be useful in preventing the proliferation of seborrheic keratoses, although they do not eliminate existing ones.


One of the most crucial aspects, is the importance of obtaining a correct diagnosis carried out by a qualified dermatologist. One should never underestimate the importance of an evaluation by a dermatologist.

Seborrheic keratoses are very common skin lesions, and should not affect your overall well-being. Remember, skin care is a crucial aspect of your overall health.

As a dermatologist, I have the knowledge and tools necessary to make an accurate diagnosis, including detailed clinical examination and, when necessary, additional diagnostic procedures such as dermatoscopy or biopsy. 


With affection and dedication,

Pedro Vilas Boas