Mucosal resection and endoscopic submucosal dissections (EMR, ESD)

Pathomorphological examination of the material after EMR and ESD — is a comprehensive analysis of large areas of mucosa or submucosa removed en bloc. These minimally invasive procedures (endoscopic mucosal resection and submucosal dissection) are used to treat early cancer and large precancerous lesions of the gastrointestinal tract. Histological examination of such material is critical to confirm the radicality of the operation.

Research objective: The main task is to accurately stage the tumor process and assess the completeness of the removal of the formation. Unlike a conventional biopsy, the study of a whole layer of tissue allows the pathologist to study the architectonics of the tumor within the entire specimen, which is key to predicting recovery without major surgery.

What does the pathologist evaluate:

• Histological type of tumor: detailed determination of the nature of the neoplasm (adenoma, adenocarcinoma, neuroendocrine tumor).

• Degree of differentiation (G): assessment of the aggressiveness of malignant cells.

• Depth of invasion (pT): precise measurement of micrometers of tumor growth into the submucosa (levels SM1, SM2, SM3), which determines the risk of metastasis.

• Vertical and horizontal resection margins (R0/R1): checking for the absence of tumor cells both on the sides and in the deep area of the cutoff.

• Lymphovascular and perineural invasion: searching for tumor cells in lymphatic, blood vessels, or around nerve fibers.

Clinical significance: The pathologist's conclusion after EMR/ESD determines whether the procedure was curative. If the tumor is removed within healthy tissues (R0) and there is no evidence of deep invasion, the patient is considered cured. If there are signs of a high risk of metastasis, the patient is offered additional surgical treatment (organ resection).

When is it prescribed:

• after removal of flat or large adenomas of the stomach and intestines;

• treatment of early esophageal cancer (e.g., Barrett's esophagus);

• removal of early stage gastric carcinomas (T1a/T1b);

• endoscopic treatment of submucosal neoplasms (GIST tumors, neuroendocrine tumors).