Intraepithelial Lymphocytosis of the Resection Margin in the Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma

Background: Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a disease involving the intestine and is often diagnosed in surgically resected specimens. The disease prognosis of MEITL is fatal because of rapid recurrence and leakage after excision. Recently, in microscopic finding of MEITL, intraepithelial lymphocytosis in mucosa that were grossly intact has been reported. In this study, we evaluated the intraepithelial lymphocytosis of the resection margin to determine the reason for the early recurrence or leakage in MEITL.

Materials and Methods: We reviewed the medical records of all patients who were diagnosed with small intestine lymphoma from January 1995 to June 2018 at our medical center. We analyzed a tissue array from 8 patients diagnosed with MEITL. The expression of CD3, CD5, and CD8 were analyzed by immunohistochemistry.

Results: A total of 8 cases of small intestine lymphoma were collected in this period. There were three men (37.5%) and five women (mean age 55 years). Two patients died without initiation of chemotherapy. Six patients received chemotherapy after resection of MEITL (4 patients received CHOP regimens, 2 patients received ProMACE-CyBOM regimens), but five patients died within 6 months (mean survival time 4.1 months, range 0.3-12.1 months). Only one patient survived for 5 years. On gross examination, the distance to the resection margin was 7.58 cm (3.8-14.0 cm) on average. Microscopic examination revealed intraepithelial lymphocytosis at least of one of the resected margins in all case. Immunohistochemical staining for CD3, CD5, and CD8 was performed on the resection margins. As a result, severe intraepithelial lymphocytosis accompanied by aberrant loss of CD5 was observed in 6 cases (75%).

Conclusion: In the MEITL, an intraepithelial lymphocytosis accompanied by aberrant CD5 loss is frequently observed in the resection margin, even if the resection margin is grossly intact, and there is no clear microscopic involvement of the lymphoma especially on low power. This fact is thought to be related to the early recurrence or leakage of MEITL at the surgical site.