Exploring the clinicopathological characteristics of submucosal tumor-like esophageal squamous cell carcinoma and the diagnostic significance of endoscopic ultrasound: a comprehensive analysis.

Background: Completely intramural growth submucosal squamous cell carcinoma of the esophagus, also known as SMT-like esophageal squamous cell carcinoma (ESCC), represents a rare and distinct form of esophageal cancer. Its white light endoscopic manifestations resemble those of esophageal subepithelial lesions, and biopsy pathology is often negative, leading to potential oversight or misdiagnosis. This study aimed to comprehensively summarize the clinicopathological and endoscopic ultrasound (EUS) characteristics of patients with SMT-like ESCC while also evaluating the immunohistochemical expression of these patient.

Methods: This study collected clinical data, including demographic and clinicopathological data, as well as EUS findings, from six patients with SMT-like ESCC. Immunohistochemical analysis was also conducted on tumor tissues to assess the expression of CK7, CK19, CK20, TTF-1, SMA, S-100, Melan-A, CD117, Mucin (MUC) 2, and MUC5.

Results: In EUS, SMT-like ESCC is characterized by nonuniform hypoechoic lesions with indistinct borders, often exhibiting a burr or serrated appearance. Most of these lesions involved multiple levels. Cytological specimens obtained through EUS-guided fine needle aspiration (EUS-FNA) revealed suspected squamous cell carcinoma with positive expression of CK5/6, P40, and P63, further confirming the diagnosis of ESCC. Additionally, four patients exhibited CK7+/CK20- immune-expression profiles, and all patients had positive CK19 expression. TTF-1, SMA, S-100, Melan-A, CD117, MUC2, and MUC5 were negative.

Conclusion: Combining EUS with EUS-FNA is a valuable approach for diagnosing and differentiating SMT-like ESCC. Furthermore, the characteristic CK7+/CK20- immune profile suggested a potential origin from the esophageal submucosa glands.