Epidermal Inclusion Cyst
- Author: Linda J Fromm, MD, MA, FAAD; Chief Editor: Dirk M Elston, MD more...
Epidermoid cysts represent the most common cutaneous cysts. While they may occur anywhere on the body, they occur most frequently on the face, scalp, neck, and trunk.
Historically, epidermoid cysts have been referred to by various terms, including follicular infundibular cysts, epidermal cysts, and epidermal inclusion cysts. The term epidermal inclusion cyst refers specifically to an epidermoid cyst that is the result of the implantation of epidermal elements in the dermis. Because most lesions originate from the follicular infundibulum, the more general term epidermoid cyst is favored. The term sebaceous cyst should be avoided because it implies that the cyst is of sebaceous origin. Finally, the term milia refers to very small, superficial epidermoid cysts.
Epidermoid cysts are benign lesions; however, very rare cases of various associated malignancies have been reported.[2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]
Epidermoid cysts result from the proliferation of epidermal cells within a circumscribed space of the dermis. Analysis of their lipid pattern demonstrates similarities to the epidermis. In addition, epidermoid cysts express cytokeratins 1 and 10, which are constituents of the suprabasilar layers of the epidermis. The source of this epidermis is nearly always the infundibulum of the hair follicle, as evidenced by the observation that the lining of the 2 structures is identical.
Inflammation is mediated in part by the horny material contained in epidermoid cysts. Extracts of this material have been shown to be chemotactic for polymorphonucleocytes.
Studies have suggested that human papillomavirus (HPV) and exposure to ultraviolet light (UV) may play a role in the formation of some epidermoid cysts, particularly verrucous cysts with coarse hypergranulosis.[14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25]
The manner in which carcinomas may arise within epidermoid cysts is unclear. In a series of epidermoid cysts with carcinoma, immunohistochemical results for HPV were negative, suggesting that HPV is not likely to play a role in the development in squamous cell carcinoma (SCC) in epidermoid cysts. Chronic irritation or repetitive trauma to the epithelial lining of the cyst has been suggested to play a role in malignant transformation; however, this relationship has not been established.
No racial predilection has been identified. Pigmentation of epidermoid cysts is common in individuals with dark skin. In a study of Indian patients with epidermoid cysts, 63% of the cysts contained melanin pigment.
Epidermoid cysts are approximately twice as common in men as in women.
Epidermoid cysts may occur at any age; however, they most commonly arise in the third and fourth decades of life. Small epidermoid cysts known as milia are common in the neonatal period.
Epidermoid cysts are usually asymptomatic; however, they may become inflamed or secondarily infected, resulting in swelling and tenderness. Rarely, malignancies, including basal cell carcinoma, Bowen disease, SCC (most common of these rarities), mycosis fungoides, and melanoma in situ, have developed in epidermoid cysts.
Handa U, Kumar S, Mohan H. Aspiration cytology of epidermoid cyst of terminal phalanx. Diagn Cytopathol. 2002 Apr. 26(4):266-7. [Medline].
Aloi F, Tomasini C, Pippione M. Mycosis fungoides and eruptive epidermoid cysts: a unique response of follicular and eccrine structures. Dermatology. 1993. 187(4):273-7. [Medline].
Barr RJ, Headley JL, Jensen JL, Howell JB. Cutaneous keratocysts of nevoid basal cell carcinoma syndrome. J Am Acad Dermatol. 1986 Apr. 14(4):572-6. [Medline].
Bauer B. Carcinoma arising in a sebaceous cyst. IMJ Ill Med J. 1979 Sep. 156(3):174-6. [Medline].
Cameron DS, Hilsinger RL Jr. Squamous cell carcinoma in an epidermal inclusion cyst: case report. Otolaryngol Head Neck Surg. 2003 Jul. 129(1):141-3. [Medline].
Delacretaz J. Keratotic basal-cell carcinoma arising from an epidermoid cyst. J Dermatol Surg Oncol. 1977 May-Jun. 3(3):310-1. [Medline].
King LA, Barr RJ, Gottschalk HR. Mycosis fungoides with underlying epidermoid cysts. Arch Dermatol. 1979 May. 115(5):622. [Medline].
Levine DJ, Robertson DB, Varma VA. Familial subconjunctival epithelial cysts associated with the nevoid basal cell carcinoma syndrome. Arch Dermatol. 1987 Jan. 123(1):23-4. [Medline].
Lopez-Rios F, Rodriguez-Peralto JL, Castano E, Benito A. Squamous cell carcinoma arising in a cutaneous epidermal cyst: case report and literature review. Am J Dermatopathol. 1999 Apr. 21(2):174-7. [Medline].
Ogata K, Ikeda M, Miyoshi K, et al. Naevoid basal cell carcinoma syndrome with a palmar epidermoid cyst, milia and maxillary cysts. Br J Dermatol. 2001 Sep. 145(3):508-9. [Medline].
Perse RM, Klappenbach RS, Ragsdale BD. Trabecular (Merkel cell) carcinoma arising in the wall of an epidermal cyst. Am J Dermatopathol. 1987 Oct. 9(5):423-7. [Medline].
Tanaka M, Terui T, Sasai S, Tagami H. Basal cell carcinoma showing connections with epidermal cysts. J Eur Acad Dermatol Venereol. 2003 Sep. 17(5):581-2. [Medline].
Swygert KE, Parrish CA, Cashman RE, Lin R, Cockerell CJ. Melanoma in situ involving an epidermal inclusion (infundibular) cyst. Am J Dermatopathol. 2007 Dec. 29(6):564-5. [Medline].
Egawa K, Kitasato H, Honda Y, Kawai S, Mizushima Y, Ono T. Human papillomavirus 57 identified in a plantar epidermoid cyst. Br J Dermatol. 1998 Mar. 138(3):510-4. [Medline].
Egawa K, Honda Y, Inaba Y, Ono T, De Villiers EM. Detection of human papillomaviruses and eccrine ducts in palmoplantar epidermoid cysts. Br J Dermatol. 1995 Apr. 132(4):533-42. [Medline].
Egawa K, Honda Y, Inaba Y, Kojo Y, Ono T, de Villiers EM. Multiple plantar epidermoid cysts harboring carcinoembryonic antigen and human papillomavirus DNA sequences. J Am Acad Dermatol. 1994 Mar. 30(3):494-6. [Medline].
Egawa K, Inaba Y, Ono T, Arao T. Cystic papilloma' in humans? Demonstration of human papillomavirus in plantar epidermoid cysts. Arch Dermatol. 1990 Dec. 126(12):1599-603. [Medline].
Egawa K, Egawa N, Honda Y. Human papillomavirus-associated plantar epidermoid cyst related to epidermoid metaplasia of the eccrine duct epithelium: a combined histological, immunohistochemical, DNA-DNA in situ hybridization and three-dimensional reconstruction analysis. Br J Dermatol. 2005 May. 152(5):961-7. [Medline].
Kato N, Ueno H. Two cases of plantar epidermal cyst associated with human papillomavirus. Clin Exp Dermatol. 1992 Jul. 17(4):252-6. [Medline].
Kawase M, Honda M, Niimura M. Detection of human papillomavirus type 60 in plantar cysts and verruca plantaris by the in situ hybridization method using digoxigenin labeled probes. J Dermatol. 1994 Oct. 21(10):709-15. [Medline].
Kitasato H, Egawa K, Honda Y, Ono T, Mizushima Y, Kawai S. A putative human papillomavirus type 57 new subtype isolated from plantar epidermoid cysts without intracytoplasmic inclusion bodies. J Gen Virol. 1998 Aug. 79 (Pt 8):1977-81. [Medline].
Lee S, Lee W, Chung S, et al. Detection of human papillomavirus 60 in epidermal cysts of nonpalmoplantar location. Am J Dermatopathol. 2003 Jun. 25(3):243-7. [Medline].
Morgan MB, Stevens GL, Somach S, Tannenbaum M. Carcinoma arising in epidermoid cyst: a case series and aetiological investigation of human papillomavirus. Br J Dermatol. 2001 Sep. 145(3):505-6. [Medline].
Park HS, Kim WS, Lee JH, et al. Association of human papillomavirus infection with palmoplantar epidermal cysts in Korean patients. Acta Derm Venereol. 2005. 85(5):404-8. [Medline].
Rios-Buceta LM, Fraga-Fernandez J, Fernandez-Herrera J. Human papillomavirus in an epidermoid cyst of the sole in a non-Japanese patient. J Am Acad Dermatol. 1992 Aug. 27(2 Pt 2):364-6. [Medline].
Shet T, Desai S. Pigmented epidermal cysts. Am J Dermatopathol. 2001 Oct. 23(5):477-81. [Medline].
Karacal N, Topal U, Kutlu N. Popliteal epidermoid cyst: an unusual location. Plast Reconstr Surg. 2004 Sep 1. 114(3):830-1. [Medline].
Baran R, Broutart JC. Epidermoid cyst of the thumb presenting as pincer nail. J Am Acad Dermatol. 1988 Jul. 19(1 Pt 1):143-4. [Medline].
Egawa K, Kitasato H, Ono T. A palmar epidermoid cyst, showing histological features suggestive of eccrine duct origin, developing after a bee-sting. Br J Dermatol. 2000 Aug. 143(2):469-70. [Medline].
Pandhi R, Gupta S, Kumar B. Multiple epidermoid cysts on photodamaged skin sebaceous gland hyperplasia and senile. J Eur Acad Dermatol Venereol. 2001 Mar. 15(2):184-5. [Medline].
Bechara FG, Sand M, Rotterdam S, Altmeyer P, Hoffmann K. Multiple epidermal inclusion cysts after axillary liposuction-curettage: a rare complication of a frequent procedure. Int J Dermatol. 2008 Nov. 47(11):1197-8. [Medline].
Leppard B, Bussey HJ. Epidermoid cysts, polyposis coli and Gardner's syndrome. Br J Surg. 1975 May. 62(5):387-93. [Medline].
Besser FS. Pachyonychia congenita with epidermal cysts and teeth at birth: 4th generation. Br J Dermatol. 1971 Jan. 84(1):95-6. [Medline].
Takeshita T, Takeshita H, Irie K. Eruptive vellus hair cyst and epidermoid cyst in a patient with pachyonychia congenita. J Dermatol. 2000 Oct. 27(10):655-7. [Medline].
Suliman MT. Excision of epidermoid (sebaceous) cyst: description of the operative technique. Plast Reconstr Surg. 2005 Dec. 116(7):2042-3. [Medline].
Lieblich LM, Geronemus RG, Gibbs RC. Use of a biopsy punch for removal of epithelial cysts. J Dermatol Surg Oncol. 1982 Dec. 8(12):1059-62. [Medline].
Mehrabi D, Leonhardt JM, Brodell RT. Removal of keratinous and pilar cysts with the punch incision technique: analysis of surgical outcomes. Dermatol Surg. 2002 Aug. 28(8):673-7. [Medline].
Zuber TJ. Minimal excision technique for epidermoid (sebaceous) cysts. Am Fam Physician. 2002 Apr 1. 65(7):1409-12, 1417-8, 1420. [Medline].
Yang HJ, Yang KC. A new method for facial epidermoid cyst removal with minimal incision. J Eur Acad Dermatol Venereol. 2009 May 3. [Medline].
Barclay L. IDSA: skin and soft tissue infections guidelines updated. Medscape Medical News. Available at http://www.medscape.com/viewarticle/827399. Accessed: June 26, 2014.
[Guideline] Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of america. Clin Infect Dis. 2014 Jul 15. 59(2):e10-52. [Medline]. [Full Text].
Silver SGHo VCY. Benign epithelial tumors. Freedberg IM, Eisen AZ, Wolff K, et al, eds. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York: McGraw-Hill; 2003. 778-779.