Invasive squamous cell carcinoma within verrucous carcinoma.

A case of invasive squamous cell carcinoma within a verrucous carcinoma is presented in order to illustrate the potential problem of underdiagnosis of these lesions. The epidemiology, natural history and histopathology of verrucous carcinoma, and features which distinguish it from invasive squamous cell carcinoma, are reviewed. Unless rigorous attention is paid to histologic detail, a focus of invasive squamous cell carcinoma may escape detection and radiation-induced anaplastic transformation may later be suspected.