Author: Kawaroreet Karwal MS2, Y, Miller-Monthrope, Dermatologist/Dermatopathologist, Toronto, Canada, 2024

Definition: Epidermoid cysts (Epidermal inclusion cysts) are common benign skin lesions formed by the proliferation of epidermal cells within a confined space in the dermis. 

Etiology: Epidermoid cysts can develop in individuals of any age but are most common in adults. They arise from the infundibulum of hair follicles.

Symptoms: Symptoms are generally mild, but cysts can become inflamed, painful, or infected, leading to erythema, tenderness, and discharge of a foul-smelling substance. 

Signs: These cysts are typically slow-growing and can occur anywhere on the body but are most frequently found on the face, neck, and trunk. The cysts present as firm, round, and mobile nodules, often with a central punctum. They contain keratinous material that can be oily in consistency.

Complications: In rare cases, cysts may rupture or cause significant discomfort.

Treatment: Treatment is usually not necessary unless the cysts are symptomatic or cosmetically concerning. Management options include intralesional steroid injections to reduce inflammation, incision and drainage for infected cysts, and definitive management via surgical excision to remove the cyst and its capsule completely.

References:

1.     Zuber, T. J. (2002). Minimal excision technique for epidermoid (sebaceous) cysts. American Family Physician, 65(7), 1409-1412.

2.     Lee, H. E., Chieng, N., & Marchetti, M. A. (2018). Common skin lesions. Primary Care: Clinics in Office Practice, 45(3), 353-374.

3.     O’Neill, A. C., & Gallo, R. L. (2012). Sebaceous glands, cysts, and tumors. In Dermatology (pp. 1560-1571). Elsevier.