Epidermoid cyst

Epidermoid cyst refers to the benign cyst that appears from the upper portion of a hair follicle and is encapsulated into a thin layer of epidermis-like epithelium. These cysts usually are filled  lipid-abundant debris and keratin.

Epidermoid cysts often affect adults, especially young and middle-aged individuals are the target group. Men have a higher prevalence than women in developing epidermoid cyst(s).

Certain genetic disorders, such as basal cell naevus syndrome and Gardner syndrome, contribute to the development of multiple epidermoid cysts.

Generally, epidermoid cyst arise from the occluded pilosebaceous unit. The non-hair-bearing sites of the body like palms of hands and sole of foot can also be affected by the epidermoid cyst as a result of traumatic implantation of epidermal cells in the dermis where keratin is present in the epithelium-lined sac.

The epidermoid cyst has defined clinical features. It appears in the form of a firm, either fair or yellowish colour, round papule or nodule attached to the surface of the skin. However, it can also be mobile throughout deeper layers. The diameter varies between 1 and 3 centimetres. Central punctum is present. Central punctum can also cause the foul-smelling cheesy debris.

Epidermoid cysts usually appear on the central trunk of the body affecting chest and shoulder as well as face. Usually, these particular cysts are asymptomatic and can appear either alone or in multiples.

If the cyst ruptures its contents into the dermis layer, it will cause redness, swelling, and tenderness. The rupturing can be the result of trauma or bacterial infection (e.g. Escherichia coli and Staphylococcus aureus).

Surgical excision can cause bleeding, scarring, and secondary bacterial infection. If the cyst ruptures or its capsule has not been completely excised, the cyst may reappear.

In rare cases, the cutaneous squamous cell carcinoma can arise within the epidermoid cyst.

An epidermoid cyst is diagnosed clinically. The biopsy is not usually needed; however, the lesion can be surgically excised either for cosmetic reasons or due to causing complications.

Majority of small and uncomplicated epidermoid cysts do not require medical interventions. However, as previously mentioned, the most effective treatment for these cysts is the surgical excision. The complete removal of the cyst decreases its rates of recurrence. This can be challenging to achieve since the cyst can rupture.

If infection results, antibiotics, incision, and drainage can be used.

Epidermoid cysts are usually benign and grow slowly.