Quantification of Collagen IV in Normal, Potentially Malignant and Malignant lesions of the Oropharynx: A Pilot Study

The incidence of oropharyngeal cancer is on the rise which is attributed to an increase in human papilloma virus (HPV) infections. HPV positive oropharyngeal carcinomas have a very different outcome to HPV negative malignancies and are therefore considered a separate disease entity. Some oropharyngeal lesions are preceded by dysplastic lesions; however, the behaviour of such lesions is unpredictable. In this pilot study, we aimed at assessing the distribution and morphology of collagen type IV expression, which is one of the constituents of blood vessel basement membrane, in the connective tissue of normal, potentially malignant and malignant oropharyngeal lesions. Histological sections were stained for collagen type IV using immunohistochemistry and scanned to obtain digital images. ImageJ was used to assess the distribution of collagen type IV positive particles using fractal geometry and to compare different morphometric parameters. Our data compared changes in the spatial distribution, size and shape of collagen type IV positive “particles” between normal, potentially malignant and malignant oropharyngeal tissues. Additionally, we compared these parameters between HPV positive and HPV negative oropharyngeal carcinoma samples. The observed patterns are indicative of changes in blood vessel formation and organisation associated with disease progression in the oropharynx. Quantification of changes in blood vessels is important from a clinical point of view as it enhances our understanding of the disease process and could aid in predicting disease progression, behaviour and potentially inform the development of new methods for drug delivery.