Verrucous squamous cell carcinoma of the larynx: evidence for increased metastatic potential after irradiation.

Verrucous squamous cell carcinoma is a rare type of well-differentiated squamous cell carcinoma with a characteristic morphologic appearance and specific clinical behavior. It has been claimed that this tumor may undergo dedifferentiation after radiotherapy; this will result in a more aggressive behavior. From 1968 to 1980, we have diagnosed and treated 569 squamous cell carcinomas of the larynx. Fourteen of them were reported to exhibit verrucous features macroscopically. These tumors were histopathologically reexamined. All 569 cases were stratified with regard to tumor stage (less than or equal to T2 N0 M0) and treatment (irradiation). Six patients of 340 were then diagnosed as having verrucous squamous cell carcinomas, according to the Ackerman criteria. The patients were followed for at least 5 years and regional metastases of poorly differentiated carcinoma developed in at least two patients in the verrucous carcinoma group within 2 1/2 years after full-dose irradiation. Among the patients with nonverrucous carcinoma, this frequency was estimated to be 3%. This study provides evidence that metastatic spread that occurs after irradiation is approximately 10 times more frequent (p less than 0.05) for T1-2 laryngeal verrucous carcinomas, as compared to the common type of squamous cell carcinoma.