EPIDERMAL INCLUSION CYST
EPIDERMAL INCLUSION CYST ICD-10: L72.810
• An epidermal inclusion cyst occurs secondary to traumatic implantation of epidermis into the dermis. Traumatically grafted epidermis grows in the dermis, with accumulation of keratin within the cyst cavity, enclosed in a stratified squamous epithelium with a well-formed granular layer.
• The lesion appears as a dermal nodule (Fig. 9-33) and most commonly occurs on the palms, soles, and fingers.
• It should be excised.
• Synonym: Traumatic epidermoid cyst.
FIGURE 9-32 • Trichilemmal cyst A firm, dome-shaped nodule on the scalp. Pressure by the cyst has caused atrophy of hair bulbs, and it thus appears without hairs.
FIGURE 9-33 • Epidermal inclusion cyst A small dermal nodule on the knee at the site of the laceration.