Seborrhoeic keratosis (SK) is a benign (non-cancerous) proliferation of squamous epidermal cells that is wart like on the skin. Sometimes also described as hyperpigmented liver spots but liver spot term is reserved for lentigo.

They are very commonly seen in elderly patients and can have very similar morphology as other skin lesion that should be ruled out. Seborrhoeic keatosis are commonly confused with skin tags which are formally known as acrochordon that are fleshed colored and pedunculated.

SKs are usually benign and only a concern when there is a sudden massive amount present known as “Leser Trelat sign” which may indicate an underlying gastrointestinal neoplasm.

The Pathophysiology of Leser-Trelat sign is likely related to various cytokines and other growth factors produced by the neoplasm that cause the abrupt appearance of multiple seborrhoeic keratoses.

Cause and Risk factors

The cause in unknown but typically run in families. As mentioned, this lesion is benign, non-contagious and very common in elderly.

Symptoms and Clinical Presentations

There is no specific symptoms that can be mentioned except (signs of neoplasm in the context of Leser-Trelat sign)

The Leser-Trelat sign is the explosive onset of multiple seborrhoeic keratoses (many pigmented wart like skin lesions), often with an inflammatory base. As mentioned above, this can be an ominous sign of internal malignancy as part of a paraneoplastic syndrome. The associated neoplasms are gastrointestinal adenocarcinomas such as (stomach, liver, colorectal and pancreas) and others malignancies of the renal, breast, lung as well as lymphoid tissue.

The most typical description of SK include: Raised discolored wart-like plaque with (stuck-on with greasy/velvety surface, waxy, coin-like) appearance. In addition, these lesion are:

  • Painless lesion, and usually spare palm and soles of feet
  • They can gradually turn darker in color (therefore you need to rule skin cancer, especially melanoma).
  • Can appear as brown, black or light tan growth on the face, chest, shoulders or back or almost anywhere.

However, physical exam of the lesion are usually the means to diagnosis but can be confirmed with a biopsy or to rule out cancer.


  • Seborrhoeic keratosis is usually clinically diagnosed and the key is to rule out similar skin lesion.
  • Histological morphology appear as keratin pseudocyst (horn cyst).
  • Some differentials to rule out: Skin tags, Warts, Moles, Actinic keratoses, and Skin cancer.

Treatment and Management

The treatment of SK are mainly for cosmetic reasons:

  1. Cryotherapy with liquid nitrogen is a commonly use method.
  2. Curettage (scraping the surface of the lesion to thin it out) are also used in areas where liquid nitrogen are contraindicated.
  3. Ablation (vaporizing the lesion with laser)
  4. Electrocautery (burning the lesion with electric current)