Cutaneous Adnexal Cysts Revisited: A Novel Classification Based on Morphological and Molecular Features

The document introduced a new classification system for cutaneous adnexal cysts, based on both morphological and molecular characteristics, to clarify the origins of these skin lesions. It categorized cysts by examining their lining, identifying epidermal cysts by their granular layer and lamellar keratinization, tricholemmal cysts by their undulating wall and compact keratinization, and other cysts like steatocystoma, dermoid cyst, and folliculosebaceous hamartoma by their crenulated lining. Additionally, hidrocystomas were recognized by a cuboidal epithelial lining with apocrine decapitation secretion. The document also noted specific cytokeratin expression patterns, such as CK17 in steatocystoma and CK10 in epidermal cysts, which are indicative of the cysts' origins. This classification aimed to provide a better understanding of the nature and origins of cutaneous adnexal cysts.