Type B2 Vessels and Infiltrative Growth Patterns B and C Are Associated with Lymphatic Invasion in Pt1a-Lamina Propria Mucosa Esophageal Squamous Cell Carcinoma.

Background Tumor growth pattern correlates with outcomes in patients with esophageal squamous cell carcinoma (ESCC), however, the clinical significance of the tumor growth pattern in pT1a-lamina propria mucosa (LPM) type of ESCC was unclear. This study was conducted to clarify clinicopathological features of tumor growth patterns in pT1a-LPM type ESCC and the relationship between tumor growth patterns and magnifying endoscopic findings. Methods Eighty-seven lesions diagnosed as pT1a-LPM ESCC were included. Clinicopathological findings including tumor growth pattern and narrow band imaging with magnifying endoscopy (NBI-ME) in the LPM area were investigated. Results Eighty-seven lesions were classified as infiltrative growth pattern-a (INF-a): expansive growth ( n = 81), INF-b: intermediate growth ( n = 4) and INF-c: infiltrative growth pattern ( n = 2). Lymphatic invasion was shown in one INF-b and one INF-c lesion. NBI-ME and histopathological images were matched for 30 lesions. The microvascular pattern was classified into types B1 ( n = 23) and B2 ( n = 7) using the JES classification. All 23 type B1 lesions were classified as INF-a without lymphatic invasion. Type B2 lesions were classified as INF-a ( n = 2), INF-b ( n = 4) and INF-c ( n = 1), and lymphatic invasion was present in two lesions (INF-b and INF-c). The rate of lymphatic invasion was significantly higher in type B2 than type B1 ( p = 0.048). Conclusions The tumor growth pattern of pT1a-LPM ESCC was mostly INF-a in type B1 patterns. Type B2 patterns are rarely present in pT1a-LPM ESCC, however lymphatic invasion with INF-b or INF-c was frequently observed. Careful observation before endoscopic resection with NBI-ME is important to identify B2 patterns to predict histopathology.