Keratinizing dysplasia of the upper aerodigestive tract

Premalignant squamous epithelial lesions of the upper aerodigestive tract (UADT) present a challenge in their diagnosis as well as in their diagnostic reproducibility among pathologists. Unlike the nonkeratinizing dysplasias of the uterine cervix that show a continuum from mild dysplasia to moderate dysplasia to severe dysplasia (ie, carcinoma in situ) before development of invasive carcinoma, the majority of dysplastic epithelial changes of the UADT are keratinizing dysplasias in which invasive carcinoma may develop from dysplasia limited to the lower basal zone in the absence of full thickness dysplasia. In this context, the justification of using the designation carcinoma in situ in the classic sense (ie, full thickness dysplasia) is questionable. As such, there are significant problems in the histologic grading of the keratinizing dysplasias of the UADT that are compounded by the inability to identify with any degree of reproducibility those morphologic changes that will progress to invasive carcinoma unless treated appropriately. This article will attempt to delineate the clinical parameters associated with oral and laryngeal dysplastic lesions, as well as discuss the morphologic spectrum of keratinizing dysplasias of the UADT.