Clinicopathologic factors and outcomes of histologic discrepancy between differentiated and undifferentiated types after endoscopic resection of early gastric cancer

Histologic discrepancies among specimens obtained by forceps biopsy and endoscopic resection (ER) between the differentiated and undifferentiated types often occur in early gastric cancer (EGC). This study aimed to evaluate the predictive clinicopathologic characteristics and clinical implications of histologic discrepancies in EGC. From August 2005 to March 2012, 596 lesions from 579 patients underwent ER for EGC. The lesions studied were diagnosed as the differentiated histologic type from forceps biopsy specimens. The lesions were grouped according to the occurrence of histologic discrepancy between the differentiated and undifferentiated types in specimens obtained by ER as concordant (n = 570) or discordant (n = 26). The main outcome measures were en bloc resection, complete resection, and curative resection rates. The histologic discrepancy rate was 4.4 % among the studied lesions. Larger size, lesion location in the mid third of the stomach, easy friability, exudates, and submucosal invasion shown on endoscopic ultrasound were significantly related to histologic discrepancy in the univariate analysis. In the multivariate analysis, lesion location in the mid third of the stomach [odds ratio (OR) 5.34, 95 % confidence interval (CI) 1.59-19.13] and easy friability (OR 29.26, 95 % CI 2.30 to > 999.9) were significant factors associated with histologic discrepancy. The complete resection and curative resection rates were significantly lower and the additional operation rates after ER were significantly higher in the discordant group. The EGCs with histologic discrepancy between the differentiated and undifferentiated types changed the therapeutic outcomes of ER. Easily friable lesions located in the mid third of the stomach carry a significant risk for histologic discrepancy in undifferentiated histology when ER of EGCs is performed.