Primary endometrial squamous cell carcinoma with molecular Characterization: A case report.

BACKGROUND

Primary endometrial squamous cell carcinoma (PESCC) is an extremely rare malignancy and represents a diagnostic challenge due to its histologic and immunophenotypic overlap with cervical squamous cell carcinoma involving the endometrium. Data regarding its molecular characteristics and their relevance to the 2023 FIGO molecular-integrated staging system remain limited.Case Presentation: We describe a postmenopausal woman presenting with abnormal uterine bleeding. The initial pathological interpretation suggested cervical intraepithelial neoplasia grade 3. However, repeat hysteroscopy and endocervical curettage did not identify a primary cervical lesion, supporting an endometrial origin. The patient underwent total hysterectomy with bilateral salpingo-oophorectomy and sentinel lymph node mapping. Final pathology confirmed moderately differentiated PESCC with superficial myometrial invasion. Immunohistochemistry demonstrated diffuse squamous marker expression and limited hormone receptor positivity. Molecular testing showed microsatellite stability, absence of POLE mutation, and abnormal p53 expression, corresponding to FIGO 2023 stage IICm-p53abn.

CONCLUSION

Current evidence suggests that PESCC may exhibit molecular and immunophenotypic features that differ from conventional endometrial adenocarcinoma; however, available data remain sparse. Further accumulation of molecularly characterized cases is necessary to clarify its biological behavior and staging implications.