Cysts (Dermoid, Epidermal, Sebaceous)

– A slow-growing, benign cystic tumor found in the subcutaneous tissue below the skin or in the intradermal tissue of the skin.

Causes and Incidence

Cyst formation is commonly caused by inflammation, internal rupture of an acne pustule or whitehead, impaired localized circulation, or trauma. Some individuals may be genetically predisposed to cyst formation.

Disease Process

Cysts contain a soft, yellow-white, cheesy substance that is often fetid and that forms when a hair follicle becomes obstructed. The contents of the cyst are determined by the type of cyst. Dermoid cysts are located deep in the subcutaneous tissue; have walls of keratinizing epidermis containing sweat glands, hair follicles, and sebaceous glands; and are often present at birth. Epidermal cysts (i.e., acne cysts) are found in the epidermis on the face, scalp, neck, and back; they contain laminated layers of keratin. Sebaceous cysts, or wens, occur primarily on the scalp and contain soft keratin, epidermal debris, and greasy material.

Symptoms

Cysts are found on or under the skin, are generally less than 3 cm in diameter, and are round, firm, globular, and movable to the touch. They are nontender unless infected. Cysts, particularly sebaceous type, can grow as large as a grapefruit.

Potential Complications

Cysts may become infected.

Diagnostic Tests

A characteristic lesion is seen on clinical examination.

Treatments

Surgery
Excision of the cyst and cyst wall; incision and drainage of infected cysts.

Drugs
Antibiotics for infected cysts.

General
Instruction not to touch, squeeze, or pick lesions, since this may lead to infection.