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epidermoid cyst (wen, infundibular cyst)
The most common cutaneous cyst, derived from epidermis or the epithelium of hair follicle. They are formed by a cystic enclosure that becomes filled with keratin & lipid-rich debris.
Epidemiology:
- middle-aged adults
Pathology:
1) implanted epidermis grows within the dermis
2) epidermal-like wall - stratified squamous epithelium with an apical granular layer
3) keratin accumulates within the cyst & cysts fill with keratinaceous material
3) often connected to surface by keratin-filled pores
* histopathology images [3]
Clinical manifestations:
1) lesion appears as a dermal nodule
2) distribution: face, neck, upper arms, scrotum, trunk
- most commonly on trunk [2]
3) generally solitary lesions, but may be multiple
4) 0.5 to 5 cm nodules
- may have central punctum from which rancid fluid may be expressed [2]
5) cream-colored pasty content of cyst with odor of rancid cheese
6) scrotal lesions may calcify
7) because of their thin walls rupture is common
8) inflammation may accompany rupture
* images [3,4]
Laboratory:
- skin biopsy not necessary
Differential diagnosis:
- lipoma: softer & less compressible, no central punctum
Management:
- excision of cyst (removal of entire cyst wall) [2]
Specific
cholesteatoma
milium
General
cyst
skin neoplasm
Database Correlations
OMIM 131600
References
- Color Atlas and Synopsis of Clinical Dermatology, Common
and Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY,
1997, pg 162
- Medical Knowledge Self Assessment Program (MKSAP) 18,
American College of Physicians, Philadelphia 2018
- Fromm LJ, Elston DM (images)
Medscape: Epidermal Inclusion Cyst
http://emedicine.medscape.com/article/1061582-overview
- DermNet NZ. Cysts (images)
http://dermnetnz.org/lesions/cysts.html