Transformation of epithelioma adenoides cysticum into multiple rodent ulcers: fact or fallacy.

This historical study has examined the persistent controversy about the propensity of epithelioma adenoides cysticum (EAC) to transform into multiple rodent ulcers, by reviewing cases reported through the years that seemed to support the idea. After focusing on the biological behaviour and natural history of the tumours and comparing them with our present knowledge of the behaviour of EAC, we believe that these cases were incorrectly diagnosed. Rather than EAC, they were probably examples of the naevoid basal cell carcinoma syndrome. The latter syndrome was actually established by the recognition that patients who have multiple rodent ulcers that appear early in life and behave aggressively usually have a constellation of associated developmental defects and that the tumours sould be classified as genetically determined basal cell carcinomas and not as EAC.