PS02.025: CHARACTERISTICS OF SUPERFICIAL BASALOID SQUAMOUS CELL CARCINOMA TREATED BY ENDOSCOPIC RESECTION

Background Basaloid squamous cell carcinoma (BSCC) is a rare esophageal carcinoma. And the characteristics especially in early stage is unknown. Methods The aim of this study is to clarify the characteristics of superficial BSCC. Thirteen patients (9 males and 4 females) with BSCC treated by endoscopic resection (12 ESD and 1 EMRC) from January 2000 to March 2017 were enrolled in this retrospective study. The median age was 67 (57–83). The median follow-up period was 24 (12–115) months. T1a-EP/LPM and T1a-MM/T1b-SM1 without lymph duct invasion (LDI) was followed up. T1a-MM/T1b-SM1 with LDI or T1b-SM2 were treated by additional treatment (AT). Results 1. En-bloc resection and R0 resection rate was 100% and 100%, respectively. 2. Macroscopic type; 0-IIa, 0-IIb and 0-IIc was 4, 1 and 8, respectively. 3. The median tumor diameter was 27 (2–62) mm. 4. Invasion depth; T1a-LPM, T1a-MM/T1b-SM1, and T1b-SM2 was 3, 5 and 5, respectively. 5. Histological characteristics; All BSCC were covered by SCC or non-neoplastic squamous epithelium. 6. Endoscopic characteristics; SMT like appearance was found in 46% (6/13). Yellowish nodules were observed in 23% (3/13). This finding was observed, when BSCC exist superficial epithelial layer covered by thin non-neoplastic epithelium. 7. Prognosis A: T1a-LPM (N = 3). Two patients are alive without recurrence, and 1 patient died of other disease. B: T1a-MM/SM1 (N = 5). Two of 3 patients without LDI were followed up and alive. Remaining one patient wanted to be treated by CRT, and alive. Two patients had LVI, however they were followed up without AT because of patient's hope. One is alive, and another died of other disease. C: T1b-SM2 (N = 5). Two and one patients were treated by surgery and chemotherapy, respectively, and alive without recurrence. Remaining two patients were followed up without AT. One of 2 patients are alive without recurrence. Another patient dead of other disease. Conclusion 1. All of BSCC were covered by SCC or non-neoplastic epithelium. 2. SMT like appearance and yellowish nodules under squamous cell epithelium were the characteristic endoscopic findings. 3. 40% of T1aMM/T1bSM1 had LDI. It's higher than that of SCC. Therefore, En-bloc resection is necessary for the detailed histological examination. Disclosure All authors have declared no conflicts of interest.