What is it?
The cysts that are found more frequently are the epidermal cyst and trichilemmal cyst. The content of both is not sebum (fat) but keratin, the substance that forms the outermost layer of skin.
Epidermal cysts are the most common and result from the proliferation of epidermal cells into the dermis, which may be due to a genetic tendency. The milium is a micro epidermal cyst, more superficial located.
Trichilemmal cysts and pilar cysts are less frequent and originate from hair follicle, occurring mainly on the scalp. These were formerly called sebaceous cysts.
Characteristics and symptoms
The lesions are spherical, usually movable, painless, of elastic consistency, or hard. They vary from small cysts (less than 1cm) to lesions with several centimeters in size. The head, neck and trunk are the most commonly affected areas. It may be visible a central and dark opening of a hair follicle.
The cysts are asymptomatic, but if over bones on the trunk or on the scalp, they can cause discomfort when lying down or leaning against hard surfaces.
In the case of inflammation of the cyst, secondary to rupture of the capsule or infection of its content, the cyst becomes red, hot and painful.
Milium: tiny lesions, yellowish or whitish, very superficial, often located on the face and especially around the eyes. In some cases the milium may reach larger sizes, as in the photo below. It can also occur in scars or after dermabrasion (a procedure which is done by sanding the skin).
The treatment of cysts is surgical. Depending on the size, type and location of the lesion, the procedure could be just the incision, drainage of the cyst contents and destroying the capsule with caustic substances.
Most recommended is the complete removal of the cyst including the capsule (excision and suture). The permanence of the capsule, or a fragment of it, may be responsible for the return of the lesion.
It is important to avoid squeezing the cysts, as this can cause the rupture of its capsule and drainage of its content into the skin, causing intense local inflammation. Inflamed cysts should be treated with anti-inflammatory drugs and antibiotics, according to each case, and with the drainage of the content.
The milium can be destroyed with the application of certain acids by a dermatologist or through a very small incision to remove the content.