What’s Seborrheic Keratosis (SK) | Main Types of SKs and Symptoms 2021

Seborrheic Keratosis
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Seborrheic Keratosis (SKs) are benign skin lesions that are found in large numbers.

They commonly emerge in the fourth and fifth decades of life, and their frequency rises as people become older and spend more time in the sun. They can resemble warts and appear as well-circumscribed “stuck-on” plaques or papules.

They are normally asymptomatic, although they can become irritated and inflamed due to friction from clothes or on their own.

Because of their benign nature, no treatment is required, but if they become irritating, itchy, or bothersome, cryotherapy and curettage can be used as a first line of defence. Malignant melanoma is the most common differential diagnosis and a source of patient worry.

Seborrheic keratosis is a kind of epithelial tumour that is benign. It usually appears as a keratotic plaque that is flat or elevated. It might appear as a single tumour or as a cluster of tumours.

A seborrheic keratosis can be mistaken for a variety of skin conditions. Not only benign tumours, but also malignant neoplasms, fall within this category. Precancerous skin lesions are also included.

A man is characterised as having an expanding tumour on his belly. Despite the clinical appearance of an irritable seborrheic keratosis, microscopic analysis of the biopsied tissue samples revealed an in situ squamous cell carcinoma.

Other neoplasms with symptoms similar to seborrheic keratosis are discussed.


We discuss the case of a 90-year-old man with no prior medical history who appeared with asymptomatic axillary lesions that had progressed over the previous two decades.

Four dented hyperpigmented tumours with extremely restricted cerebriforms spanning 12 cm along their longitudinal axis were discovered during the clinical examination.

Seborrheic keratosis was suspected after a dermoscopic examination revealed cerebriform convolutions. Without evidence of viral infection or malignant change, histology confirmed the diagnosis. A surgical resection was performed on the patient, which left a permanent scar.


The benign proliferation of immature keratinocytes causes seborrheic keratosis, which manifests as well-defined, round or oval, flat-shaped macules. They usually take a long time to grow, might thicken over time, and seldom dissolve on their own.


There is a lack of accurate and up-to-date information on SK epidemiology; nonetheless, it is generally recognised that the prevalence of SK increases with age. A greater prevalence has also been recorded among persons of colour.

Tindall and Smith evaluated a group of persons over 64 years old in the United States in 1963 and discovered that 88 percent of them had at least one seborrheic keratosis. 10 There has never been a sex difference recorded in SKs.

Seborrheic Keratosis: What Is It?

A seborrheic keratosis is a common, non-cancerous wart-like development that tends to multiply with age. Because of its potential to develop to great sizes and resemble moles, it is frequently mistaken for skin cancer.

A seborrheic keratosis is a harmless skin growth that looks like a mole. In their lives, almost everyone will have at least one. They usually first arise in mid-adulthood, and their frequency rises as you become older.

They’re not dangerous and don’t need to be treated, but if they irritate you, you can get them removed.

Epidermal tumours are a kind of skin development that includes seborrheic keratoses. However, this does not rule out the possibility of malignancy.

Moles and warts are epidermal tumours, thus they are technically the same thing. This simply implies that they are additional cells clustered on the epiderma, the skin’s outer layer. They aren’t thought to be a skin cancer risk factor.

What are the Different Types of Seborrheic keratoses lesions?

These are some of the most prevalent Seborrheic keratoses (SK) lesions:

Seborrheic Keratoses

Seborrheic keratoses are most commonly found on the face, neck, and trunk. They can resemble warts. They might have a velvet or waxy feel to them.

The lesions appear to have become adhered to your skin. Do not attempt to remove them by peeling or scratching them.

Dermatosis Papulosa Nigra (DPN)

DPN is characterised by tiny, elevated, black pimples. Your face, neck, chest, and upper back are all affected.

People with darker skin are more likely to get these lesions. Women are more likely to get these lesions, and there is frequently a family history of them.

Stucco Keratoses (SK)

SK are tiny grey lesions on the surface of the skin. They resemble warts in appearance. The legs and forearms are the most common sites for these lesions. Usually, there are a number of these lesions. Men are more likely to have them.

Flat Seborrheic Keratoses (FSK)

FSK are brown areas on the face, chest, or arms that are oval in shape. As you become older, the number of these lesions increases.

Pedunculated Seborrheic Keratoses (PSK)

PSK are a kind of darker seborrheic keratosis with a stem. These might be seen on the neck or in the armpits.


Although experts believe some kinds of Seborrheic Keratosis may be inherited as a dominant feature, the actual aetiology is unknown.

Human features, such as typical genetic disorders, are the result of the interplay of two genes for that condition, one from the father and the other from the mother.

In dominant illnesses, a single copy of the disease gene (inherited from either the mother or the father) is expressed, thereby “dominating” the normal gene and causing the disease to manifest.

The likelihood of passing the condition along to children from an afflicted parent is 50% for each pregnancy, regardless of the child’s gender).

This Factors that increase your Risk

If you’re over 50, you’re more prone to get seborrheic keratoses. If you have a family history of the ailment, you’re also more likely to have them.


Warts, moles, and skin cancer can all be confused with seborrheic keratoses. They have a waxy appearance and appear to be adhered to the skin. Some of them could resemble a lump of dark candle wax.

Others look like barnacles. They might be as little as a grain of rice or as large as an inch wide. They aren’t painful, but they could itch or bother you. When characterising seborrheic keratosis, there are four factors to consider:


The most prevalent sites for growths are the head, shoulder, chest, belly, and back. They never appear on the palms of the hands or the soles of the feet.


Lesions normally begin as tiny, rough lumps that thicken and acquire a warty surface over time. They might seem waxy and “stuck on” at times.


They are typically round or oval in shape.


Brown is the most common colour, however they can also be yellow, black, or white.

The lesions are seldom painful, but depending on their location, they might be unpleasant. Picking or scratching them can cause bleeding, edoema, and infection.

Except for palms, soles, and mucous membranes, one or more spots can appear anywhere on the body (eg, in the mouth or rectum).

They aren’t going anywhere. Seborrheic keratosis does not convert into cancer, however certain malignancies look like it.

They begin as light brown to skin-colored, flat spots that range in size from circular to oval and are light brown to skin-colored (usually less than a half inch, but sometimes much larger).

Seborrheic keratoses can develop dark brown to virtually black with a “stuck on” look as they thicken and rise above the skin surface. The texture of the surface might be smooth or rough.

What is the Procedure for Diagnosing Seborrheic Keratoses?

The skin growth will be examined by your physician. If it’s not apparent what the growth is, he or she may need to take a sample (biopsy) of it.

  • Bleeding or itching.
  • It turns red and swollen.
  • It ranges in colour from dark brown to black.

When should you Go to the Doctor?

Although a seborrheic keratosis isn’t harmful, you shouldn’t disregard any skin growths. It might be difficult to tell the difference between innocuous and harmful growths. Melanoma can resemble seborrheic keratosis.

If you have any of the following symptoms, see a doctor.

  • There has been a recent increase in growth.
  • An existing growth has changed its appearance.
  • Only one type of growth exists (seborrheic keratosis usually exists as several).
  • A growth is purple, blue, or reddish-black in hue.
  • A growth with uneven boundaries (blurred or jagged).
  • An inflamed or unpleasant growth.

Make an appointment with your doctor if you’re concerned about any changes. It is preferable to be overly careful than to overlook a potentially dangerous issue.

How are Treated?

It is not necessary to treat seborrheic keratoses. However, if one bothers you or you don’t like how it looks, you can get it removed by your doctor.

Your physician may:

  • Put it in the freezer (cryotherapy).
  • Remove it from the equation (curettage or excision).
  • Make use of an instrument that burns it away (electrocautery or laser treatment).

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