How are keratinous cysts differentiated from other benign skin lesions?

Updated: Jan 30, 2020
  • Author: Ginard I Henry, MD; Chief Editor: Gregory Gary Caputy, MD, PhD, FICS  more...
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Answer

Answer

These lesions can be found in almost any location. Variations found on the extremities, particularly the fingers and toes, may be a traumatic form of inclusion. In contrast, the pilar cyst occurs almost exclusively on the scalp. Its hallmark is a trichilemmal keratinization pattern. This pattern is different from the lamellated form because the well-defined granular layer is lacking.

Additionally, focal calcification is common. Amino acid analysis of both types of cysts demonstrates that the epidermoid cyst is most likely to originate from the infundibular portion of hair follicles. Another conclusion is that the trichilemmal cyst tends to have an origin from the epithelium of the hair follicle that is at or distal to the level of sebaceous ducts. In this location, no typical granular layer is present.


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