Angiogenesis in Superficial Esophageal Squamous Cell Carcinoma: Assessment of Microvessel Density Based on Immunostaining for CD34 and CD105

The esophagus is the only organ where changes in the superficial microvasculature from normal squamous epithelium to invasive cancer are evident by magnifying endoscopy. We investigated in detail the features of angiogenesis in early-stage esophageal cancer using CD34 and CD105 immunostaining, and also the correlation between angiogenesis and mononuclear cell infiltration. Using 10 samples of normal squamous epithelium, 7 samples of low-grade intraepithelial neoplasia, and 45 samples of superficial esophageal cancer, we determined the microvessel density at hot spots showing positive staining for CD34 and CD105. We observed the histological features of CD34- and CD105-positive microvessels that corresponded to observations made by magnifying endoscopy. We then investigated the correlation between microvessel density and each histological situation or the grade of mononuclear cell infiltration. The histological features of CD34- and CD105-positive microvessels were able to explain the morphological changes in the microvasculature during cancer progression observed by magnifying endoscopy. The microvessel density for CD34 or CD105 was significantly correlated with each of the histological types (P < 0.001, rS = 0.51 and 0.76, respectively). Mononuclear cell infiltration at CD105 hot spots was most frequent in M1 and M2 cancer (94.7%). The correlation between the degree of mononuclear cell infiltration and microvessel density for CD105 staining was also significant (P < 0.001, rS = 0.49). The microvessel density based on CD34 and CD105 immunostaining can be used to corroborate observations of superficial esophageal squamous cell carcinoma made by magnifying endoscopy. Mononuclear cell infiltration may play an important role in angiogenesis at the early stage of cancer progression.