Case Report: Complete endoscopic submucosal dissection for occult superficial esophageal squamous cell carcinoma concealed by a large esophageal leiomyoma.

INTRODUCTION

Benign-appearing gastrointestinal lesions may occasionally conceal malignancy and pose a diagnostic challenge. Esophageal leiomyomas are benign neoplasms; however, careful mucosal assessment remains essential to avoid missed diagnoses.

CASE DESCRIPTION: We report the case of a 53-year-old asymptomatic woman in whom a large esophageal leiomyoma masked a superficial esophageal squamous cell carcinoma (ESCC). Subtle mucosal irregularity detected on endoscopy prompted further evaluation with narrow-band imaging and targeted biopsies, confirming carcinoma in situ. Following multidisciplinary discussion and shared decision-making that incorporated patient preferences, selective endoscopic submucosal dissection (ESD) was performed to achieve complete resection of the carcinoma while preserving the underlying leiomyoma.

CONCLUSION

En bloc resection was achieved without complications. Histopathology confirmed a well-differentiated superficial ESCC with submucosal invasion (>200 μm, pT1b), negative horizontal and vertical margins, and no lymphovascular invasion. After postoperative pathology review, additional surgical treatment was recommended because of the risk associated with submucosal invasion; however, the patient strongly declined surgery. Contrast-enhanced CT showed no evidence of regional lymph node metastasis, and the patient subsequently underwent radiotherapy at a local hospital. At 2-year follow-up, endoscopic re-examination showed no recurrence, and the leiomyoma remained stable in size. This case underscores the importance of careful evaluation for occult malignancy hidden behind benign-appearing lesions and demonstrates that favorable outcomes can be achieved through individualized, multidisciplinary management, including endoscopic resection, adjuvant therapy, and close surveillance.