Skin cyst are spherical formations isolated from the surrounding tissues, representing an accumulation of sebum and horny masses in the epidermal membrane (true skin cyst) or cavities inside the dermis filled with heterogeneous contents, without an epidermis shell (false skin cyst). They are localized over the entire surface of the skin. The size of the cyst can reach a chicken egg, the skin above it is not changed, with injury or rupture of the formation, inflammation may develop. Subjectively, the patient’s well-being is not disturbed. The cyst is diagnosed dermatoscopically, clinically, histologically. If necessary, ultrasound and MRI are performed. Treatment consists in monitoring the patient or radical removal of the formation.
A skin cyst is an intradermal cavity lined with epithelium (or without it), filled with various contents. Most often in dermatology there are sebaceous cysts, or atheromas of the skin. Strictly speaking, cysts are at the intersection of interests of different medical disciplines: dermatology, cosmetology, endocrinology, surgery, oncology. However, dermatologists and cosmetologists tend to face the visual side of the problem more often. In the structure of skin diseases, the share of skin cyst accounts for about 1%. Gender, age, race, and seasonal differences were not revealed.
A feature of dermal cysts is their ability to exist on the skin for a long time, remaining unnoticed due to their small size. This is fraught with spontaneous dissemination of the process as a result of injuries (shaving, peeling), hyperinsolation, hypothermia, hormonal restructuring of the body (puberty, pregnancy, menopause), contact with substandard cosmetics, other negative causes, as well as the possibility of malignant degeneration of cysts. It is with this feature that the relevance of the issue at the present stage is connected.
There are three main reasons for the formation of cysts: violation of the secretion of sebaceous glands of the skin, violation of keratin formation in the hair canal, disorder of neuroendocrine regulation of the endocrine glands associated with calcium metabolism. Normally, the sebaceous glands of the skin are hormone-dependent. Male and female sex hormones control the proliferation of skin cells, sebum secretion. If male sex hormones predominate over female ones (age, menopause, hormone intake, tumors), the tissue of the sebaceous glands of the skin grows with an increase in secretion production.
Sebum, consisting of two fractions – sebaceous gland secretion and epidermal cell lipids – changes its consistency due to the predominance of the hypersecretory fraction. In combination with compensatory hyperkeratosis at the mouth of the hair follicle, this leads to blocking of the outflow of secretions, blockage of the mouth and the formation of a cavity in the dermis lined with epithelial cells. If the hair follicle is injured, instead of fat, the cavity is filled with epidermal cells, since the processes of keratinization in order to restore the defect prevail over sebum formation. Violation of the neuroendocrine regulation of the thyroid, thymus gland, parathyroid, genital glands, triggers the process of calcification in the skin, in which the formed intradermal cavities are filled with calcium. People with oily or combination skin, seborrhea, and acne are more likely to form skin cyst.
All cavity intradermal formations are divided into two large groups: true and false. True skin cyst are cavities that have an inner shell. These include:
- An epidermal cyst (atheroma) is a spherical cavity inside the skin, covered with a shell of epithelial cells and containing sebum. In turn, it is divided into true atheroma (cyst in the shell of non-ovoid origin) and false (retetion) atheroma (plug of sebum).
- A hair cyst is an analogue of an epidermal cyst, but without a hole in the center.
- Implantation cyst (parasitic) – occurs as a result of injury to the epidermis, lined with injured layers.
- Milium is a superficial epidermal cyst of minimal size.
- Dermoid is a congenital cystic formation.
False skin cyst are cavities without an epithelial inner shell. These include:
- Synovial cyst – dermal cavity of epithelial cells, skin appendages. It occurs more often in elderly people.
- Calcinosis is the deposition of calcium in the tissues of the human body, including in the skin.
- Pseudomilium is the deposition of sebum in the area of scars and scars.
The clinical picture of cystic formations depends on the type of pathological process. All of them are cavities isolated from the surrounding tissues with or without an inner shell, filled with heterogeneous contents. Epidermal cyst is the most common. There are true atheroma and pseudoatheroma.
True atheroma is sheathed, contains the secret of the sebaceous glands, the remains of cells of the stratum corneum of the epidermis. Visually it looks like a subcutaneous node capable of reaching more than 5 cm in circumference, dotted with keratin-clogged pores all over the surface. It is located on the cheeks, auricles, in the upper third of the back, on the genitals. The node is constantly increasing in size, which eventually tears it from the inside, and all the contents of the cyst pour into the dermis with pain and the development of inflammation. This course of the disease requires immediate medical intervention. True atheroma grows slowly, often becomes infected, becomes dense, painful to the touch. If it is located shallow, then there is a spontaneous opening of purulent masses, their pouring out, and the inflammatory process is stopped. Deep cysts are prone to abscess formation, require surgical intervention, and antibacterial therapy.
A false cyst grows rapidly, is localized mainly in the area of the scalp and genitals, which is the key to timely access to a dermatologist due to a violation of the quality of life. A milium is a small epidermal cyst, an atheroma in miniature.
The hair cyst is similar to an atheroma, but has no central opening, smooth, dense, domed. Usually these are multiple formations, since such cysts are localized where the hair grows. A hair cyst is anatomically unrelated to the epidermis, if it reaches a large size, the hair around it falls out. The cyst is filled with keratin, prone to calcification. The rupture of the cyst causes pain, initiates inflammation in the skin.
Implantation cyst is the result of skin injury, “pressing” of the epidermis into the depth of the skin layers. The cyst is located on the palms and soles in the form of an intradermal formation with horn cells inside. Due to the constant threat of mechanical opening, it is subject to removal.
Dermoid is a congenital defect of embryogenesis in the form of a cyst containing ectoderm derivatives inside. The clinic depends on the size of the cyst and its location. With an increase in the size of the formation, the functions of neighboring organs suffer, the rupture causes pain and inflammation. Dermoid is able to transform into squamous cell skin cancer.
Among false cysts, the palm belongs to the synovial cyst. This disease is common among the elderly. The cyst looks like a cavity filled with a colloid. Localized most often in the area of the nail bed, it can provoke nail dystrophy.
Calcinosis cutis is an illustration of malfunctions in the neuroendocrine system that regulates metabolic processes. Calcium begins to be deposited directly in the dermis, subcutaneous fat, and underlying muscles. Clinically, the islands of the trace element look like dense areas of the skin, resembling asymmetric nodes of bluish color, growing along the perimeter, prone to ulceration and suppuration.
Pseudomilium is a mini cyst of sebum located in the recesses of the epidermis and covered with cells from above. It is not opened independently.
Diagnosis and treatment
Usually, the appearance of the cyst leaves no doubt about the diagnosis, histological examination is mandatory after the removal of the formation. In unclear cases, ultrasound of a skin neoplasm is connected, which not only confirms the presence of a cavity, but also determines its size. Rare localization of the cyst requires MRI of soft tissues. Differentiate cysts with lipomas, dermatofibromas, hygromas, paronychia, adenophlegmon, squamous cell skin cancer.
The method of treatment depends on the size of the cyst. Milium, cysts of small size are subject to observation by a dermatologist. The remaining formations are removed after consultation with a cosmetologist, surgeon, plastic surgeon. The usual surgical intervention is applied with a skin incision and mandatory peeling of the cyst walls, curettage. In addition, a radio-wave method of cyst removal, laser destruction, electrocoagulation is used, minimizing manipulative traumatism. In all cases, the contents of the cyst evaporate, the shell collapses. With complicated skin cyst, a course of antibiotic therapy is initially carried out.
Prevention of the formation of skin cyst consists in observing the rules of personal and intimate hygiene, a diet with a restriction of fats, sugar, salt; it is recommended to avoid injury to the skin, monitor the hormonal balance of the body. The prognosis is favorable for life.