P1.114. Endoscopic Diagnosis of Esophageal Cancer Using Ultra-High Magnification Endocytoscopy

Abstract

Abstract Topic Esophageal Cancer: New Diagnostic Modalities (Including PET, PET-CT, New Tracers) Background Background Ultra-high magnification endoscopic observation using endocytoscopy (EC) enables cellular-level visualization and allows in vivo assessment comparable to histopathological diagnosis. We previously proposed a three-tier classification system based on surface cellular morphology and reported that Type 3 lesions can be diagnosed histologically as malignant using EC images alone. Methods Patients and Methods Type classification Type 1 (non-cancerous) is defined as low nuclear density, a small nuclear-to-cytoplasmic (N/C) ratio, and absence of nuclear atypia. Type 2 (borderline lesion) shows increased nuclear density and nuclear size variation but is insufficient for a definitive diagnosis of malignancy. Type 3 (malignant) is characterized by nuclear enlargement, high nuclear density, and marked nuclear atypia. Between November 2011 and June 2025, 843 EC examinations with corresponding histopathological evaluation were performed. We retrospectively evaluated the diagnostic accuracy of the Type classification based on observations of 359 cases and 325 esophageal cancer lesions. Results Results EC observation was performed in 288 cases of squamous cell carcinoma (SCC) involving 323 lesions and in 36 cases of non-SCC esophageal cancer. Among the 331 adequately visualized cases, 314 (94.6%) were classified as Type 3 and 10 (3.0%) as Type 2, indicating that cancer cells were identifiable in the vast majority of lesions. Of the 79 patients who underwent endoscopic treatment, 17 (21.5%) were diagnosed as malignant based solely on EC findings, and biopsy was omitted. Among these, four had previously been diagnosed as borderline lesions by biopsy at referring institutions or at our hospital but were definitively diagnosed as esophageal carcinoma by EC. The biopsy-omitted lesions consisted of nine type 0-IIb and eight type 0-IIc lesions, with a median tumor diameter of 15 mm (range, 2–55 mm). Histological examination of resected specimens after endoscopic submucosal dissection (ESD) confirmed squamous cell carcinoma in all cases. Conclusion Conclusion EC observation of the esophagus enables definitive in vivo histopathological diagnosis of esophageal cancer and is particularly useful for small lesions that remain borderline on biopsy.