Morphometric study of nucleolar organiser regions (AgNOR) in HPV- associated precancerous lesions and microinvasive carcinoma of the oral cavity

A morphometric study of silver-stained nucleolar organiser regions (NOR) was performed on histological sections from routinely paraffin-embedded blocks of 26 oral biopsy specimens (21 cases of leukoplakia consisting of 13 low, 4 moderate, 4 severe degree of dysplasia, and 5 cases of microinvasive carcinomas). In situ hybridisation (ISH) for HPV-DNA was performed on serial sections of the same samples. The following parameters were studied: V NOR (single AgNOR volume per nucleus), TV NOR (total AgNOR volume per nucleus), and R.I. (AgNOR's roundness index). The results highlight that not all the morphometric features of AgNORs allow the discrimination between lesions with dysplasia of low, moderate and severe degree and microinvasive carcinoma. TV NOR appeared useful, while the other morphometric parameters appeared statistically not significant i differentiating between the different lesions. These findings suggest that high values of TV NOR in oral dysplasia could represent a risk marker, identifying a subgroup of lesions with a worse prognosis, constituting then a possible indication for rigorous clinical management and/or for complex treatment of these HPV-associated preneoplastic lesions.