Duplicated Muscularis Mucosae Invasion has Similar Risk of Lymph Node Metastasis and Recurrence-free Survival as Intramucosal Esophageal Adenocarcinoma

Duplicated muscularis mucosae (MM) in early esophageal adenocarcinoma (EAC) can cause overstaging of the disease on endoscopic ultrasound and pathology specimens. No study has determined the correlation between lymph node metastasis and invasion in the space between duplicated MM in pathologic tumor stage (pT) 1 EAC. Hematoxylin and eosin-stained slides from surgically resected pT1 EAC (n = 99) were reviewed for tumor configuration, grade, level of invasion (lamina propria/inner MM, space between duplicated MM, and submucosa), quantitative depth of invasion in millimeter, and lymphovascular invasion (LVI). These pathologic characteristics were correlated with lymph node status and recurrence-free survival (RFS). All specimens had duplicated MM with thick-walled blood vessels. Tumor differentiation was well in 37, moderate in 47, and poor in 15 specimens. EAC invaded the lamina propria/inner MM in 28 cases, duplicated MM space in 41 cases, and submucosa in 30 cases. LVI was identified in 23 tumors. Eleven patients had lymph node metastasis. Quantitative depth of invasion as a continuous variable (P = 0.002), poorly differentiated histology (P = 0.028), presence of LVI (P = 0.001), and submucosal invasion versus duplicated MM/lamina propria invasion (P = 0.02) were associated with increased risk of lymph node metastasis and shorter RFS by univariate analysis. By multivariate analysis, LVI was an independent predictor of lymph node status and RFS. EAC invasion into the space between duplicated MM confers a similar risk of lymph node metastasis and recurrence as those of intramucosal EAC, and LVI is the best predictor of lymph node status and RFS in pT1 EAC.