Peritumoral granulomatous reaction in endometrial carcinoma: association with DNA mismatch repair protein deficiency, particularly loss of PMS2 expression.

MMR protein-deficient ECs, particularly those with PMS2 loss, occasionally show PGRs in addition to stromal lymphoid infiltrates and TILs. Therefore, PGRs could be considered to constitute a histological prompt for consideration of Lynch syndrome. The potential prognostic significance of PGRs in EC requires further study.