Post-gastric endoscopic mucosal resection surveillance biopsies: evaluation of mucosal changes and recognition of potential mimics of residual adenocarcinoma.

Endoscopic mucosal resection (EMR) offers curative treatment for patients with node-negative early gastric carcinoma of less than 2 cm without ulceration or ulceration scar. Follow-up biopsies are frequently performed to ensure the absence of residual neoplasia. We performed a retrospective analysis of post-EMR biopsies from 33 patients who underwent gastric EMR. Histologic changes included inflammation (100%), stromal edema (97.0%), foveolar hyperplasia (78.8%), ectatic vessels (66.7%), epithelial atypia (60.6%), increased glandular mitoses (57.6%), epithelial anisonucleosis (54.5%), fibrinopurulent materials (51.5%), ischemia (48.5%), stromal hemorrhage (33.3%), mucin depletion (12.1%), clear cell degeneration (15.2%), and signet-ring cell-like change (6.1%). Especially, clear cell degeneration and signet-ring cell-like change were conspicuous in the area of ischemia. Residual adenocarcinomas were noted in 4 of 33 cases, and consistently showed high nuclear-to-cytoplasmic ratio with high glandular density. Glandular clear cell degeneration and/or signet-ring cell-like change were worrisome and sometimes difficult to be distinguished from residual neoplastic glands. However, these degenerative glands were usually embedded in a nondesmoplastic stroma and showed anisonucleosis of glandular epithelia. Mimics of residual adenocarcinoma, namely clear cell degeneration and signet-ring cell-like change should be judiciously assessed to avoid unnecessary surgery.