POLE and hyperinsulinemic hypoglycemia, familial, 4: This classification identifies four categories of endometrial carcinomas with distinct clinical, pathologic, and molecular features: POLE (ultra-mutated) (7%) characterized by tumors with mutations in the POLE exonuclease domain [4, 5]; Microsatellite instability (MSI)/hypermutated (28%) by mismatch repair deficiency (MMRd) [4, 6]; serous-like/copy number high (26%) by TP53 alterations [7, 8]; and copy number low/microsatellite stable (39%) [4].