Epidermoid cyst: symptoms, diagnosis and treatment of sebaceous cysts

The epidermoid cyst is also called sebaceous cyst and is one of the most common skin cysts. Appearing on the skin and originating from the hair follicle, it consists of a cystic cavity located in the dermis and filled with keratin and lipid material

It is usually more frequent in young or middle-aged individuals and the areas of the body most affected are the face, neck, upper torso and scrotum.

Usually only one cyst appears, but, in some cases, they may be multiple.

The structure consists of a dermal nodule varying in size from 0.5 to 5 cm in diameter.

It often happens that the wall of the cyst ruptures, with the caseous material escaping, causing an inflammatory reaction and intense pain.

Epidermoid cysts are in most cases treated by surgery under local anaesthesia, but care must be taken to remove the entire cyst wall to avoid recurrence.

Medications are only used to treat possible inflammation or to prepare the patient for surgery.

Types of epidermoid cysts

Epidermoid cysts are benign skin neoformations classified according to the histological features of the cyst wall or lining and according to their location.

There are several types of benign cutaneous cysts:

  • epidermal inclusion cysts: usually do not cause discomfort unless they rupture causing a painful reaction or a rapidly expanding abscess. Epidermal inclusion cysts are often characterised by the appearance of a visible spot or pore and contain white, malodorous material;
  • milia: small epidermal inclusion cysts that usually appear on the face and scalp;
  • pilar cysts (trichilemmal cysts): look similar to epidermal inclusion cysts, but mostly appear on the scalp. In addition, there is usually a genetic component that determines their appearance. If the subject has had cases in the family, he or she is more likely to develop them.

Once the nature of the cyst has been defined, it will be possible to determine the best treatment, which often involves outpatient surgery.

Symptoms of epidermoid cyst

The epidermoid cyst presents itself as a small lump visible under the skin or at the level of the scalp.

Touching it appears solid, globular, mobile and painless.

It is very rare in children and uncommon in females; it is more common in men, especially after puberty.

Sebaceous cyst is not contagious and does not develop into a malignant skin lesion.

It appears as a small subcutaneous swelling and may contain serous fluid, sebum or other semi-solid substances (such as keratin and dead cells).

It grows slowly and does not cause discomfort, except if it is touched or if one tends to remove its contents by squeezing it, in which case inflammation and/or infection may result.

Epidermoid cysts do not tend to cause any particular symptoms other than cosmetic ones: when the subject notices a small, soft, mobile swelling under the skin, he or she should consult a doctor to determine its nature.

If this type of cyst is large and/or located on the face or neck, it may give a feeling of pressure or pain, as well as being frequently unsightly.

It can develop on any part of the body except the soles of the feet and the palms of the hands, but the most frequently affected areas are the scalp, the nape of the neck, the face, the ears, the shoulders, the back, the armpits, the arms, the buttocks, the genitals, the breasts and the belly.


The formation of an epidermoid cyst is due to the occlusion of the duct of a sebaceous gland that produces its own secretion without being able to expel it due to the blockage.

As a result, the secretion solidifies and accumulates inside the gland resulting in swelling of the hair follicle visible to the naked eye.

There are risk factors that increase the likelihood of this annoyance such as tobacco consumption, alcohol, stress and anxiety situations (which alter hormone production), use of cosmetics, the presence of acne or other skin disorders, genetic disorders (such as Gardner’s syndrome or basal cell nevus syndrome) and damage to the hair follicle (e.g. lesions, abrasions or wounds).

Nutrition seems to have no correlation with the appearance of epidermoid cysts and does not appear to be a risk factor for their development.

Diagnosis of epidermoid cysts

Diagnosis of the presence of an epidermoid cyst is clinical and is performed by a general practitioner or dermatologist.

Sometimes it is sufficient to observe and palpate it to assess its location, shape and size.

In addition, palpation is used to assess its consistency: the cyst generally appears soft and elastic, due to its fat-rich content.

During the examination, the specialist makes a careful differential diagnosis to distinguish the sebaceous cyst from other types of cysts that can develop under the skin.

It is important, in fact, during the diagnosis to understand whether they are:

  • pilar cysts (multiple and localised on the scalp, they have a rounded, smooth, glabrous and pinkish surface)
  • dermoid cyst (located in the sacrococcygeal region or on the face, develops in the dermis due to a development defect, can also affect children)
  • hydrosadenitis suppurativa (a chronic inflammatory skin condition that manifests itself as cysts and abscesses in the armpit, groin, inner thigh or perianal area, often painful and characterised by pus discharge).

The most difficult cysts to diagnose are those occurring in the scrotal region or on the genitals.

In these cases they can be confused with a genital herpes simplex infection.

Only in cases of doubt, rare in reality, may the doctor request additional tests, such as:

  • an ultrasound scan to better assess the shape and content of the cyst,
  • a biopsy with removal of the cyst contents for a more thorough histological test.

In this way the doctor can ascertain that it is indeed a sebaceous cyst and exclude other diseases, even serious ones.

Treatments for epidermoid cysts

Sebaceous cysts are always curable and usually do not recur unless surgery is incomplete and inaccurate.

Antibiotics are not necessary unless there is cellulitis or otherwise signs and symptoms suggestive of bacterial overinfection.

Usually, if necessary, they are used in the form of ointments that act locally to resolve the problem.

Epidermoid cysts can be surgically removed after injecting a local anaesthetic to prevent the patient from feeling pain during the procedure.

The cyst wall must be removed completely to avoid recurrence, while cysts that have ruptured must be opened and drained.

Smaller cysts, which are often very bothersome, can be incised and drained.

If left untreated, an epidermoid cyst may become inflamed and appear red, painful and warm to the touch.

If it is subjected to trauma in an attempt to crush it, there is an increased risk of bacterial infection, which can lead to fever.

An alternative to surgery is non-ablative electrosurgery with PLEXR, a technique that uses an electromedical instrument that vaporises the sebaceous cyst.

The advantages of this technique are that

  • there is no damage to the surrounding skin tissue,
  • no preliminary injection anaesthesia is required,
  • it does not cause bleeding in the treated area,
  • it does not require stitches.

In the 2-3 days following the treatment, the treated area is swollen and a scab forms, which should not be touched.

Surgical interventions

To reduce the abscess in case of infection, drainage of the cyst (through an incision) is usually recommended.

This treatment is appropriate when the inflammation is such that the skin over the cyst has thinned, so the likelihood of a spontaneous perforation is high.

However, in these cases, surgery is not decisive, since periodic dressings will have to be performed afterwards until the inflammation is completely resolved.

Surgery is resorted to if the inflammation persists, if the sebaceous cyst causes pain or if it tends to grow in size.

This is the definitive solution for the pathology.

Before surgery, if the inflammation is deep, cortisone and antibiotic therapy is usually prescribed to reduce swelling and redness.

A particularly inflamed cyst should not be touched by the surgeon because there is a high risk of worsening the inflammation or causing a rupture of the cyst capsule, which may lead to infection.

The surgical procedure involves a small skin incision under local anaesthesia with subsequent removal of the entire cyst, including the capsule.

The latter must be removed in its entirety, as otherwise the risk of future recurrences increases.

After surgery it will take about ten days for the wound to heal, during which time the patient must undergo antibiotic therapy and periodic dressing of the affected area, which must remain covered and sterile.

In the 6-12 months following surgery, the scar should be protected from the sun’s rays to prevent it from taking on a permanent reddish colour; similarly, exposure during the hottest hours of the day should be avoided and very high sun protection (50+) should be used.

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