Supplementary Material for: Challenging Diagnostic and Therapeutic Limits: Complete Circumferential Endoscopic Dissection of a Rare and Extensive Esophageal Carcinoma

Abstract
Introduction: Basal layer type squamous cell carcinoma (BLSCC) is a rare subtype of esophageal carcinoma imposing challenges in the diagnosis and endoscopic treatment with prognostic implications. We report a case of BLSCC successfully treated by complete circumferential endoscopic submucosal dissection.
Case Presentation: A 73-year-old man with a history of a stable non-Hodgkin’s lymphocytic lymphoma presented with dysphagia. After a demanding diagnostic work-up, an almost circumferential and extensive tenuous flat lesion of the distal esophagus was found. In a multidisciplinary team discussion, a circumferential endoscopic dissection approach was decided, which proved to be curative. The final histopathological diagnosis was BLSCC, a challenging diagnosis of a rare form of squamous cell neoplasia. There were no adverse events, including esophageal stenosis, or recurrence during a 12-month follow-up.
Discussion/Conclusion: Endoscopic submucosal dissection is an effective and safe therapeutic option for this rare type of esophageal squamous cell carcinoma, even with extensive esophageal involvement.