Microvessel density and endothelial basement membrane composition in laryngeal squamous cell carcinomas

In this retrospective study we morphometrically evaluated the density of small blood vessels (microvessel density; MVD) in laryngeal squamous cell carcinomas (SCC) in order to find out if the vascular density provides relevant information on the biology and prognosis of this tumor type. In addition, we investigated the composition of the endothelial basement membrane (BM) to analyze qualitatively the role of the major BM components during tumor-associated angiogenesis. For the immunohistochemical staining of the blood vessels we used the endothelial cell marker CD31 and the BM was analyzed by immunostaining for the major components collagen-IV, laminin-1 and perlecan. Beneath the normal mucosa a mean of 18 vessels/0.41 mm2 was found. Invasive carcinomas showed a significant increase in blood vessel density to 36.3 vessels/0.41 mm2 regardless of the degree of tumor cell differentiation. Interestingly, the highest vascular density was found beneath dysplastic, but non-invasive epithelia (45.5 vessels/0.41 mm2), particularly when associated with a strong lymphoplasmacytic cell infiltration. Statistical analysis revealed a highly significant correlation between MVD and the lymphoplasmacytic infiltrate. However, we did not find any significant correlation between MVD and other clinical/biological parameters. Qualitative analysis of the endothelial BM revealed an "earliest" occurrence of laminin-1 in the obviously newly formed vessels, while collagen IV and perlecan occur at more pronounced stages of vessel formation. There was, however, no prognostically relevant information available from endothelial BM analysis. In summary, at present we do not consider the MVD in SCC of the larynx to be a prognostic factor for the individual outcome of the patient.