Sebaceous cyst: an overview of this epidermoid cyst

By Cristiano Antonino On Mar 29, 2023

Sebaceous cyst is one of the benign skin cysts and can be classified as an epidermal inclusion cyst (epidermoid cyst)

Rarely does this form of lesion cause discomfort in the person who develops it and sometimes it can disappear without any specific treatment.

However, it is not always easy for inexperienced persons to make a clear distinction between a harmless sebaceous cyst and other types of nodules or swellings of the skin.

For this reason, it is always advisable to consult your doctor or a dermatologist if new formations appear on your body.

What is a sebaceous cyst?

A sebaceous cyst is a type of subcutaneous neoformation that is absolutely benign in nature.

Its formation is caused by the occlusion of a sebaceous gland that, no longer able to dispose of its secretions, collects them by accumulating them under the skin, forming cysts.

This type of formation consists of semi-solid material formed from sebum and keratin, and upon incision the material it contains has a caseous and foul-smelling appearance.

The sebaceous cyst is enclosed by a whitish or greyish capsule and is usually roundish in shape, mobile and with a semi-solid consistency.

Usually the formation of a cyst is painless, except in cases where an infection is present.

It can also become painful if it is touched or squeezed, resulting in the escape of the material contained within.

Sebaceous cysts most frequently develop in the scalp area, behind the ears, on the face, on the back and, very rarely, on the front of the chest.

The size of this type of lesion can vary considerably and can even reach 5-6 cm in diameter.

The development of sebaceous cysts is very rare in children and also in females, while it is much more frequent in men, especially after puberty.

The prognosis is good as the cyst is always surgically treatable.

Rarely it can reform if surgical excision is not done properly.

It is always a benign lesion that can nevertheless cause discomfort depending on the anatomical area in which it arises or if it becomes infected or too large.

Causes and risk factors

As stated earlier, a sebaceous cyst forms as a result of the occlusion of a sebaceous gland with subsequent collection of keratinous, follicular and/or sebaceous material.

When a sebaceous gland or its duct (responsible for the passage of its secretions) is damaged or obstructed, the gland’s ability to dispose of keratin secretions, sebum and dead cells that continue to be produced within it is diminished.

As a result of this obstruction, material collects to form a cyst, a typically rounded subcutaneous mass visible to the naked eye.

Factors responsible for the occlusion of a sebaceous gland usually include trauma and injuries of various kinds in the affected area.

The development of cysts can therefore be promoted either by a skin condition such as acne, or by a simple scratch or surgical wound.

Other factors that appear to play a role in sebaceous gland occlusion and subsequent cyst formation include:

Tobacco use
Alcohol abuse
Anxiety and stress (leading to altered hormone production)
Use of certain cosmetics
Genetic disorders such as Gardner’s syndrome or basal cell nevus syndrome

On the other hand, there does not seem to be any connection between the formation of sebaceous cysts and poor diet, let alone genetic factors.

How to tell if you have a sebaceous cyst

As mentioned earlier, a sebaceous cyst usually does not show symptoms of any kind unless it is stimulated.

It is therefore possible to assume that you have a sebaceous cyst when you notice a semi-solid, mobile, whitish or yellowish swelling on one part of your body.

To be certain of the diagnosis, however, it is always necessary to consult your doctor in order to resolve any doubts.

Excluding the soles of the feet and palms of the hands, areas that do not have sebaceous glands, sebaceous cysts can develop anywhere on the body.

Moreover, several cysts may also develop simultaneously in one patient.

We briefly recall below the areas most affected by these benign neoformations:

Scalp. This type of cyst, unlike the others, can be hereditary and develops more in women;
Face;
Nape;
Shoulders;
Back of the ear;
Armpits;
Shoulders;
Back;
Arms;
Anal region and buttocks;
Breast;
Belly;
Genitals.

Diagnosis

In most cases, it is sufficient to visit your doctor to find out whether you have a sebaceous cyst under the skin.

In fact, the appearance of the cyst is easily recognisable and the doctor only needs to observe and palpate the affected area to make a diagnosis.

During the physical test, the specialist will have to ascertain that one is in the presence of a sebaceous cyst, eliminating the possibility of other types of cysts such as:

Pilar cysts: often multiple and localised on the scalp;
Dermoid cyst: also affects children and forms in the dermis due to a development defect, usually in the facial and sacrococcygeal areas;
Hydrosadenitis suppurativa: a chronic inflammatory condition that manifests itself with cysts and abscesses in the armpit, groin, inner thigh and perianal area.

In the remote case that the doctor has doubts about the nature of the cyst, the patient may be prescribed an ultrasound scan, which will allow the specialist to assess its content.

Depending on the case, a differential diagnosis may then be necessary to exclude more serious diseases such as tumour masses.

In cases such as this, it will be necessary to prescribe another type of investigation, a biopsy, i.e., taking a small amount of tissue and analysing it under a microscope.

If, on the other hand, the cyst has formed in particular regions of the body, it may need to be analysed to distinguish it from other types of disease such as genital herpes simplex.

How to treat a sebaceous cyst

In cases where the sebaceous cyst does not reabsorb on its own, it can be treated either with oral medication or topical solutions such as antibiotic and cortisone creams.

More often, however, especially when the lesion increases in volume or affects the aesthetic appearance, surgical removal is recommended to the patient.

The procedure consists of drainage and excision of the mass, with complete removal of the cystic capsule to avoid recurrence.

The procedure is performed under local anaesthesia and the patient is given a small incision in the area where the cyst develops to remove its contents and remove the walls of the cyst.

After the procedure, in order to avoid further complications, the patient may be prescribed an antibiotic treatment while the wound, which is sutured, must remain covered and sterile for between 7 and 10 days.

In the case of a ruptured cyst or suppuration (formation of purulent material), resulting in intense pain, removal is not possible.

What can be done in cases like this is to incise the skin to get the suppurated material out and reduce the pain sensation.

The operation, however, will not completely solve the problem and it will be necessary to carry out periodic dressings until the inflammation has passed and only afterwards to evaluate a removal operation.

Possible secondary complications

In most cases, the complication of a sebaceous cyst is the formation of pus.

This often occurs when the cyst has a small wound that allows bacteria to pass through and multiply, leading to a reaction of the immune system that attacks and eliminates them.

This accumulation of dead cells and bacteria inside the cyst forms the typical slimy, whitish liquid called pus.

In cases of bacterial infection, the cyst will appear red, painful and warm to the touch and, in severe cases, may lead to the onset of fever.

The other most frequent complication of a sebaceous cyst, as mentioned earlier, is recurrence.

In fact, the cyst, if not properly removed, could reform even after some time.

This is why it is important to rely on the hands of an expert who will take care of completely removing both the cyst and the cyst wall, thus ensuring the patient’s complete disappearance of the sebaceous cyst.

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