RARE VARIANTS OF KERATOACANTHOMA

Keratoacanthomas are made up of the same spinocellular differentiated cell material as squamous cell carcinomas, but they differ from the la tter in origin and growth properties. The majority - in our series 98% of 741 examined cases - are of the ,,crateriform'' type, which after rapid growth during the initial stage give way to spontaneous regressi on, mostly with complete restoration of the cutaneous structure. Less than 2% belong to the rare destructive variants with disturbed or abse nt regression and persistent invasive growth. Keratoacanthoma marginat um centrifugum, mutilating keratoacanthomas and aggregated keratoacant homas can lead to extremely severe defects. None of the ,,conservative '' treatment methods recommended in the literature up to now has prove d effective, with the exception of surgery and radiotherapy with tumou r ratio doses. Many publications are obviously based on uncritically i nterpreted individual observations.