Corrugated, eosinophilic cuticle lines inside of cyst wall
• Trichofolliculoma
Clinical Photograph of Eruptive Vellus Hair Cysts 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.)
Vellus Hair Cyst Low magnification shows a cyst lined by a keratinizing squamous epithelium. The cyst contents include laminated keratin and numerous transversely sectioned hair shafts .
Vellus Hair Cyst With Pilosebaceous Unit Some cysts may show a pilosebaceous unit attached to the cyst wall . Fragments of hair shafts are also present within the cystic space .
Ruptured Vellus Hair Cyst Ruptured vellus hair cysts are often accompanied by an exuberant foreign body granulomatous response as is illustrated here, with many hair shafts surrounded by inflammation.
TERMINOLOGY
Abbreviations
• Vellus hair cyst (VHC)
Synonyms
• Eruptive vellus hair cyst (EVHC)
Definitions
• Similar histology to epidermoid (follicular, infundibular type) cyst with 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)
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and numerous transversely sectioned hair shafts 
.
. Fragments of hair shafts are also present within the cystic space 
.
as is illustrated here, with many hair shafts surrounded by inflammation.
