Facial keratoacanthoma.

The keratoacanthoma is a common tumor of hair follicle origin that appears predominantly on sun-exposed skin of elderly persons. Approximately 80% of the tumors arise on the face. It is characterized by the rapid growth of a painless, dome-shaped, 10 to 25 mm solitary lesion with a central keratinous plug that undergoes spontaneous involution over 6 to 12 months, leaving behind a puckered scar. Alarming growth and early histologic appearance (pseudocarcinomatous infiltration, cell atypicality, mitoses) are suggestive of squamous cell carcinoma, but biologic behavior and tumor architecture confirm its benign nature. However, evidence that all keratoacanthomas regress is lacking, malignant transformation has been reported, and less than excisional biopsy may render a difficult histologic diagnosis either inconclusive or erroneous, even in expert hands. Excisional biopsy is recommended as expedient and definitive management that offers optimal prognosis. Local flap or full-thickness graft closure affords cosmetic results that are superior to those provided by other treatment methods.