Scalp cysts: what are the causes?

A sebaceous cyst, in response to an obstruction of the sebaceous duct.

Sebaceous cysts are the most common cause of growths on the scalp. They have a fairly soft texture and are white to yellow in colour. The sebaceous cysts form when the sebum produced by the sebaceous glands can no longer be evacuated through the sebaceous duct and a plug is created. In parallel, keratin cells from the superficial layers of the epidermis can also be trapped in the blocked duct. This mixture causes a semi-solid mass: the sebaceous cyst. This type of cyst can result from the skin's natural tendency to produce sebum and have a genetic origin or occur following hormonal changes that lead to an increase in the activity of the sebaceous glands.

How to remove a sebaceous cyst?

While some sebaceous cysts disappear spontaneously, this is not the case for all. To remove a sebaceous cyst that persists, it is necessary to consult a dermatological surgeon. If the cyst is neither infected nor in an inflammatory phase, it can be removed immediately in about twenty minutes during a procedure performed under local anaesthesia. The patient can then resume their activities. In the case of an infected cyst, antibiotics are prescribed. Once the infection is contained, the operation can be carried out.

Seborrheic dermatitis, a chronic inflammation of the scalp.

Seborrheic dermatitis is a chronic inflammatory condition that often affects the scalp. It causes red, scaly patches, sometimes taking a cystic form and can be accompanied by itching. The causes of seborrheic dermatitis are not clearly defined, although several factors are suspected, such as the proliferation of the yeast Malassezia. This microorganism feeds on the fatty acids of sebum and produces prostaglandins, cytokines that can trigger an inflammatory response in the body. A hormonal influence and a possible role of androgens on the pilosebaceous unit is also suspected.

How to respond to seborrheic dermatitis of the scalp?

To manage the progression of a seborrheic dermatitis of the scalp, it is generally recommended to use shampoos containing antifungal agents, such as selenium sulphide (from 1 to 2.5%), ketoconazole (2%) or ciclopiroxolamine (1.5%). Two applications per week are often advised initially. The usage is then gradually reduced to once a week and then once every two weeks.

Folliculitis, an infection of the hair follicles.

Folliculitis is an infection of the hair follicles typically caused by the bacterium Staphylococcus aureus, but occasionally by Pseudomonas aeruginosa. It presents as red papules and pustules at the hair follicles, often painful and itchy. The etiology of folliculitis is still somewhat unclear, but it is recognised that sweating, trauma, friction and skin occlusion can exacerbate the infection. When folliculitis is recurrent or poorly managed, it can lead to abnormal scarring of the affected follicles and obstruction of their ducts, potentially leading to sebaceous cysts.

What should be done in the case of folliculitis of the scalp?

Only a doctor can diagnose folliculitis. The management of this condition often involves the prescription of topical or oral antibiotics, such as mupirocin or clindamycin. The use of a 5% benzoyl peroxide treatment can also help to eliminate folliculitis.

A shock or physical trauma.

Head injuries and local traumas can also promote the development of cysts on the scalp. Indeed, following a more or less violent blow to the head, it is not uncommon to observe a rupture of the hair follicles. This can create a subcutaneous cavity that fills with sebum and keratin, leading to the formation of a cyst. Moreover, traumas can trigger an inflammatory response in the affected area which in turn leads to a excessive cellular proliferation. This process can result in the formation of retention cysts or epidermal cysts in the injured area.

What is the correct response after a head injury?

After receiving a blow to the head, it is recommended to visit the emergency department for imaging tests to detect any signs of bleeding. However, the small cysts that form following a shock are generally benign and disappear after a few days.

A lipoma, a benign tumour of the fatty tissues.

Lipomas are benign tumours formed by a proliferation of fat cells under the skin. Being benign, they grow slowly and are generally painless. Lipomas are often movable under the skin and have a soft texture. The exact causes of lipomas are not fully understood, but it appears that there may be a genetic predisposition in some cases. Age could also be a factor, with lipomas being more common in older individuals. Overweight individuals also seem to be more affected, as well as those with metabolic disorders such as diabetes. However, it is important to note that many people with lipomas do not have any of these risk factors.

How to remove a lipoma?

Lipomas are not harmful and do not require removal, unless they cause physical or aesthetic discomfort. In these situations, the treatment of a lipoma involves a steroid injection to reduce its size, or liposuction to remove the fatty content. However, the most common method remains surgical removal, where the lipoma is removed under local anaesthesia.

An haemangioma, caused by an abnormal proliferation of blood vessels.

Haemangiomas are benign tumours of the cells lining the blood vessels that can appear on the scalp. They typically present as red or purple spots on the skin but, when they develop more deeply, they can form masses resembling cysts. Although haemangiomas are most often present at birth or appear in young children, they can sometimes develop in adults. The precise causes of haemangiomas are currently unknown, although it appears that individuals with fair skin are more frequently affected.

What to do in case of a haemangioma?

There is no standard treatment for a haemangioma. The management depends on their size, location and the patient's age. The various options in the case of a haemangioma include active monitoring, the intake of beta-blockers, corticosteroid therapy, laser treatment and surgery.

A fibroid, an outgrowth of connective tissue.

Sometimes referred to as dermatofibromas, fibromas are benign growths made up of connective tissue. They can appear on the scalp as small round or oval masses and are sometimes mistaken for sebaceous cysts. Fibromas are often quite hard and can change colour over time. Probably genetic, their precise cause has not yet been identified.

How to respond to a fibroma?

Fibromas can be surgically removed if they cause discomfort or irritation. This procedure is performed under local anaesthesia. Cryosurgery is also a possible solution to alleviate symptoms. This involves the use of liquid nitrogen or liquid carbon dioxide. The freezing of tissues indeed allows for the elimination of the fibroma.

A basocellular carcinoma, a cancer of the scalp.

Basal cell carcinoma is a form of skin cancer that develops from the basal cells of the epidermis. It can take several forms: an open wound that does not heal, a red patch, a small pink lump, swelling, scar... Unlike benign cysts, a basal cell carcinoma can spread and invade surrounding tissues. Previous instances of skin cancer, repeated exposure to the sun or frequent inflammations of the scalp are among the main risk factors for basal cell carcinoma.

How to treat a Basal Cell Carcinoma?

A basal cell carcinoma can be treated in various ways. Most commonly, surgery is performed to completely remove the tumour. When the excision is not complete, external radiotherapy is possible. This involves using high-energy rays or particles to destroy the cancer cells. For less advanced cancers, photodynamic therapy may be suggested. Finally, some basal cell carcinomas are managed with creams containing imiquimod, an immune response modifier, pills containing vismodegib, a Hedgehog signalling pathway inhibitor, through immunotherapy, or by systemic chemotherapy.