Vellus Hair Cyst
Senait W. Dyson, MD
Key Facts
Terminology
Similar histology to epidermoid cyst with the addition of intraluminal vellus hairs
Clinical Issues
Small, discrete, follicular papules; often on the chest
Microscopic Pathology
Dermal cyst lined by bland stratified squamous epithelium with granular layer
Intraluminal laminated keratin and numerous vellus hair shafts
Top Differential Diagnoses
Epidermoid (epidermal inclusion, follicular infundibular) cyst
Milial cyst
Steatocystoma
Trichofolliculoma
 Multiple, slightly brownish small follicular papules are seen on the chest. This is a classic presentation of eruptive vellus hair cysts. (Courtesy J. Wu, MD.) |
 Low magnification shows a cyst lined by a keratinizing squamous epithelium. The cyst contents include laminated keratin  and numerous transversely sectioned hair shafts  . |
TERMINOLOGY
Abbreviations
Vellus hair cyst (VHC)
Synonyms
Eruptive vellus hair cyst (EVHC)
Definitions
Similar histology to epidermoid (follicular, infundibular type) cyst with the addition of intraluminal vellus hairs
ETIOLOGY/PATHOGENESIS
Genetics
Rare cases reported to be autosomal dominant
Rarely associated with the following diseases
Ectodermal dysplasia (anhidrotic and hidrotic)
Lowe syndrome (oculocerebrorenal syndrome)
Pachyonychia congenita
Associations
Can present concomitantly with steatocystoma multiplex (SM) and milial cysts
Some consider VHC and SM to be a variation of the same entity
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