Primary endometrial squamous cell carcinoma with endometrial atypical hyperplasia in elderly women: a case report

Background: Primary endometrial squamous cell carcinoma (PESCC) is a rare entity with poorly understood pathogenesis. Given the difficulty of pathological diagnosis, we report a case of postmenopausal PESCC to highlight the complexity of its immunohistochemical findings. Case Description: A 66 -year -old woman presented with lower abdominal discomfort and pain. Endometrial biopsy showed a papillary hyperplasia and squamous differentiation of the endometrium. Transvaginal ultrasound and pelvic enhanced computed tomography (CT) scan confirmed a mass in the uterus, and enlarged lymph nodes around the right foramen ovale and bilateral iliac vessels, suggesting a uterine malignancy. Radical hysterectomy, bilateral salpingo-oophorectomy, large omental appendectomy, sigmoid colectomy, ileostomy and intestinal anastomosis were performed. The definitive diagnosis was primary endometrial squamous carcinoma with lymph node and intestinal metastasis (stage IVB). Immunohistochemistry of tumor cells showed positive for cytokeratin 5/6, p63 and HPV16, and 30-50% of tumor cells were reactive for Ki-67. Wilms tumor 1 (WT -1) as well as estrogen and progesterone receptor were negative. Nine months after surgery, the patient died at home due to cancer progression. Conclusions: The diagnosis of PESCC is based on careful pathological examination of hysterectomy specimens by pathologists and its differential diagnosis from squamous cell carcinoma of cervical origin and endometrioid carcinoma with extensive squamous differentiation is particularly important. The pathogenesis of PESCC and its pathological phenotype are complex, further studies of a large number of cases are needed.