The regressing keratoacanthoma.

The clinical and pathological features of 11 cases of regressing keratoacanthoma are presented. These lesions were from sun-exposed skin of individuals between the ages of 58 and 92 years and were of short clinical duration (2-12 months). Histologically, these lesions showed similar features and consisted of symmetrical shallow cup-shaped invaginations of thin atrophic epidermis with overhanging edges. The underlying papillary dermis demonstrated variable degrees of inflammatory infiltrate and scarring. It is important to recognize these features as representing regressed keratoacanthoma as they may be confused with other unrelated skin conditions.