An uncommon case of POLE mutated uterine carcinosarcoma - complemented by a review of literature

Carcinosarcomas are high-grade endometrial cancers which enclose mesenchymal and epithelial differentiated components. The vast majority of these cancers belong to the p53 abnormal molecular subgroup and usually come with an unfavorable prognosis. POLE mutant carcinosarcomas are a rarity and only make up about 5% of this histologic subtype. Recent literature even suggests that this number is still an overestimation and the result of misclassification of undifferentiated or dedifferentiated endometrial cancers. Here we present a case of a 56-years old patient diagnosed with carcinosarcoma of the uterus. Hysterectomy, bilateral salpingo-oophorectomy with pelvic lymph node staging was performed and complete molecular workup of the tumor revealed an abnormal p53 expression as well as a pathologic POLE mutation. NGS was performed separately on the epithelial and mesenchymal component of this high-grade cancer and both components shared two identical POLE mutations, a known pathologic mutation, and a variant of unknown significance (VUS). This finding hints to a clonal origin of both histologic components of this tumor and supports conversion theory as mechanism of carcinosarcoma emergence. The cancer was correctly staged as FIGO 2023 Stage IAm_POLEmut and according to ESGO-ESTRO-ESP guidelines adjuvant chemotherapy no longer considered and our patient entered follow-up after a detailed discussion.