Enhanced diagnosis of extramural venous invasion in esophageal carcinoma: endothelial ETS-related gene, laminin and α-smooth muscle actin plus elastic staining.

Extramural venous invasion (EMVI), defined as tumor cell infiltration of veins beyond the muscularis propria, is an adverse prognostic factor in esophageal squamous cell carcinoma (ESCC). Although elastic stains are widely used, diagnosis remains challenging. Additional utility of vascular markers has not been systematically evaluated yet. Moreover, some EMVI tumor nests (EMVI-TN) showed partial encasement with vascular elements suggesting an invasion-independent metastatic pathway. 147 resection specimens of ESCC after surgery only were retrospectively evaluated for EMVI. ETS-related gene (ERG), laminin, and α-smooth muscle actin (α-SMA) were added and immunohistochemically evaluated on serial sections and scored semi-quantitatively as 0 (no staining), 1 or 2 (< 50% or ≥ 50% circumferential involvement, respectively). Verhoeff staining was re-scored. Score 2 was considered test-positive and 0-1 test-negative. Sensitivity, specificity, false-positive rate, positive predictive value, and negative predictive value were calculated. Only patients with complete ERG, laminin, α-SMA, and Verhoeff staining were included, comprising 52 EMVI-present and 18 EMVI-absent cases. α-SMA and re-scored Verhoeff showed the highest sensitivity (both 38/52, 73.1%), in contrast to ERG and laminin with 12/52, 23.1% and 13/52, 25.0%, respectively. Specificity was 100% for ERG, α-SMA, and Verhoeff, and 94.4% for laminin. EMVI-TN with vascular elements were identified in 9 (17.3%) cases. α-SMA showed the highest diagnostic utility, whereas ERG and laminin had limited sensitivity. In the final EMVI classification, α-SMA staining should be added to the current pathologic assessment on H&E and Verhoeff. EMVI-TN with vascular elements may represent an alternative invasion-independent metastatic pathway warranting further study.