[1161] Differentiated Dysplasia Is a Frequent Precursor or Associated Lesion in Invasive Squamous Cell Carcinoma (SCC) of the Oropharynx.

Ruza Arsenic, Michael O Kurrer. Cantonal Hospital Aarau, Switzerland; Pathologie Institut Enge, Zurich, Switzerland

Background: The recognition of the spectrum of precursor lesions of oropharyngeal SCC, their classification and their grading have remainded controversial over the last decades. This contrasts to vulvar cancer precursor lesions which are related to either HPV or chronic inflammation and can manifest – under the VIN paradigm (VIN I-III) or as differentiated dysplasia (dVIN), respectively. Oropharyngeal SCC precursor lesions are etiologically more variable, being related to smoking, HPV or chronic inflammation, and the spectrum of lesions may thus admittedly be wider, but still no clinically useful international consensus exists on histological types of precursor lesions and on the significance of individual types.
Design: We reviewed all available histological slides of patients with oropharyngeal biopsies (excluding the tonsil) and subsequent resection specimens with SCC on file in the archives of Department of Pathology of our hospital from 1992 until 2009.
Results: Five basic patterns of precursor lesions or SSC associated lesions were identified: Pleomorphic similar to full thickness severe laryngeal squamous dysplasia (24/155), basaloid stratified similar to anal basaloid dysplasia of AIN III (6/155), differentiated similar to dVIN or lichenoid lesions with large cells with large nuclei and prominent eosinophilic nucleoli, abundant eosinophilic cytoplasm and promentent desmosomes, with additional minimal basal cell layer or suprabasal cell irregularities (63/155), mixed differentiating pleomorphic with superficial maturation (43/155) as well as verrucous with open often raisin like nuclei without prominent nucleoli (11/155). Keratinization was a common but variable feature in differentiated, mixed differentiating and verrucous dysplasia. In 8/155 no precusor lesion could be identified. Progression of isolated differentiated dysplasia was documented in 13% of patients (21/155) over variable time periods ranging from months to years.
Conclusions: Full thickness epithelial dysplasia of either pleomorphic or basaloid type is present in only 20% of oropharyngeal SCC. Differentiated dysplasia is a frequent precursor or associated in situ lesion in oropharyngeal SCC. Failure to recognise differentiated dysplasia results in underdiagnosis of a sizable proportion of patients at risk for invasive carcinoma. Our cases of documented progression of differentiated dysplasia call for efforts to refine criteria for separation of differentiated dysplasia from morphologically related lichenoid lesions.
Category: Head & Neck

Tuesday, March 1, 2011 8:45 AM

Platform Session: Section G, Tuesday Morning


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