Abstract
A 69-year-old man underwent endoscopic submucosal dissection (ESD) for early gastric cancer of the lower gastric body. The lateral margin was positive, corresponding to an eCura C-1 classification, and surveillance with upper gastrointestinal endoscopy every 6 months was performed. Local recurrence was detected 4 years later, and repeat ESD resulted in an eCura C-2 classification, prompting additional surgical resection. No lymph node metastasis was identified, and the patient remained recurrence-free for 11 months. Histopathological examination of the surgical specimen revealed extensive foreign body granuloma formation involving the deep muscularis propria and subserosal tissue. The granulomas were Alcian-blue positive, with staining intensity reduced after hyaluronidase treatment, suggesting the involvement of a hyaluronic acid-containing submucosal injection agent. No granulomas were observed in the repeat ESD specimen obtained 6 months before surgery. Inflammatory cell infiltration around the lymphatic vessels was observed, suggesting the involvement of lymphatic pathways to the gradual spread and extensive distribution of the granulomatous reaction over time. Submucosal injection-related granuloma formation after ESD is rare, but extensive granuloma formation may complicate the interpretation of post-ESD findings and potentially increase the technical difficulty of subsequent treatment. Clinicians should be aware of this possibility when performing surveillance and additional treatment after ESD.