Core Dermatology Diagnoses / CategoriesNeoplastic Benign and Malignant

Epidermoid cyst

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Publish date: Posted on
Last updated: February 2, 2022

Keywords #

epidermal inclusion cyst
sebaceous cyst
infundibular cyst

Diagnosis #

Epidermoid cysts, otherwise known as epidermal inclusion cysts, are benign subepidermal nodules found most commonly on the trunk, neck, face and back.[1] They are mainly caused by follicular disruption. Cysts can originate from the infundibulum, the sebaceous duct and the outer root sheath. The epidermis can also invaginate into the dermis, resulting in follicular blockage and accumulation of keratin debris within a capsule.[1,2] These cysts are typically asymptomatic; however, rupture or infection can lead to significant inflammation of the area.[1,2]

Key Concepts #
  • Epidermoid cysts are benign subepidermal nodules. 
  • They can occur on all parts of the body.[1] 
  • Typically asymptomatic in nature, when ruptured they can become significantly inflamed, prompting a medical visit.  
  • Their pathogenesis is related to follicular plugging and build-up of keratin debris within a capsule due to invagination of epidermis into the dermis.[3] 
Epidemiology #

Epidermoid cysts most commonly occur in patients in their 20s and 30s, although they can be diagnosed at any age. They are the most common cyst type with male:female ratio of 2:1. Although typically benign, basal cell carcinoma or squamous cell carcinoma can arise within the cyst.[1]

Clinical Features #
  • Often presents as a well-demarcated, soft, mobile, flesh-colored dermal nodule with a central, dark punctum [4] 
  • Patients may report history of increased pain and inflammation after trauma to the area or spontaneous rupture 
  • Malodorous, creamy white material may be expressed from the lesion [3] 
Differential Diagnoses #
Diagnostic Workup #

Epidermoid cysts are typically a clinical diagnosis. No diagnostic workup is required.[1]

Treatment #

Treatment is not medically necessary; however, if bothersome to the patient, surgical excision or punch biopsy with complete removal of cyst wall is standard.[1] Removal of the cyst is best performed when it is not inflamed. Intralesional triamcinolone solution can calm inflammation.[1] 

References #
  1. Zito, Patrick and Richard Scharf. Epidermoid Cyst. StatPearls Publishing, 2020. 
  2. Wolff, Klaus, et al. Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology. McGraw-Hill Education, 2017. Print. 
  3. Marks, James and Jeffrey Miller. Lookingbill and Marks’ Principles of Dermatology. Elsevier, 2019. Print. 
  4. Higgins, James, et al. “Diagnosing Common Benign Skin Tumors.” American Family Physician vol. 92, no. 7, 2015, pp. 601-607. 
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