Subepithelial extension of squamous cell carcinoma in the esophagus: histopathological study using D2-40 immunostaining for 108 superficial carcinomas.

Squamous cell carcinoma (SCC) of the esophagus occasionally produces subepithelial extension (SEE) in the stroma below the non-cancerous epithelium. Little information on SEE has been obtained, therefore the purpose of the present study was to carry out a clinicopathological study using D2-40 immunostaining in 108 cases of superficial (mucosal and submucosal) SCC of the esophagus. SEE occurred in 24 cases (22.2%). The SEE was present in both mucosa and submucosa in 19 cases, but in five cases SEE was located in the mucosa. Lymphatic invasion of tumor cells was well determined on D2-40 immunostaining. In the SEE group lymphatic invasion was found in 15 cases, and in two cases there was lymphatic invasion in the lamina propria mucosa of the edge of SEE. In the SEE group 23 (95.8%) had infiltrative growth of tumor cells. Lymphatic invasion and growth pattern of tumor cells were statistically correlated with SEE. Lymph node metastases were found in 48 cases, but SEE was not correlated with nodal metastases statistically. In conclusion, esophageal SCC produces SEE from the early stage by infiltrative growth and lymphatic invasion of tumor cells. The detection of lymphatic invasion on D2-40 immunostaining in the mucosal edge of SEE is useful for evaluation of endoscopic mucosal resection tissue.