Undifferentiated endometrial carcinoma: a case report

We present the case of a 50-year-old Chinese female patient with no significant past medical history. She experienced menarche at the age of 14 years with regular menstrual cycles. The patient exhibited irregular vaginal bleeding and lower abdominal pain for 2 months. A gynecological examination revealed that the uterine fundus was at the umbilical level with mild tenderness. Routine blood tests indicated mild anemia. A pelvic ultrasound revealed an enlarged uterus with adenomyosis and a compressed endometrium, which was not clearly visualized; both ovaries appeared normal. A pelvic magnetic resonance imaging (MRI) scan suggested irregular uterine enlargement, abnormal signals in the myometrium and endometrium, restricted diffusion, and possible endometrial carcinoma with myometrial invasion. Multiple enlarged lymph nodes were observed adjacent to the abdominal aorta and bilateral iliac vessels (Fig. 1 ). Computed tomography (CT) showed an irregular soft-tissue density mass in the mid-to-lower abdomen, scattered enlarged retroperitoneal lymph nodes with partial fusion, and multiple solid pulmonary nodules, the largest measuring approximately 8 mm × 7 mm in the posterior basal segment of the left lower lobe, with metastasis being a possibility that needed to be excluded (Fig. 2 ). Endometrial and endocervical curettage pathology revealed a small amount of detached cervical glandular epithelium, changes resembling the proliferative phase of the endometrium, focal stromal decidualization, and no atypical cells. Fig. 1 A Magnetic resonance imaging suggesting endometrial carcinoma with myometrial invasion. B Multiple enlarged lymph nodes observed adjacent to the abdominal aorta and bilateral iliac vessels Fig. 2 Computed tomography scans revealing multiple solid pulmonary nodules, the largest measuring approximately 8 mm × 7 mm in the posterior basal segment of the left lower lobe A Magnetic resonance imaging suggesting endometrial carcinoma with myometrial invasion. B Multiple enlarged lymph nodes observed adjacent to the abdominal aorta and bilateral iliac vessels Computed tomography scans revealing multiple solid pulmonary nodules, the largest measuring approximately 8 mm × 7 mm in the posterior basal segment of the left lower lobe Surgical exploration revealed an enlarged uterus with multiple nodular lesions on its surface (Fig. 3 ), adhesion of the anterior uterine wall to the bladder reflection peritoneum, armor-like thickening of the bladder seromuscular layer, and partial obliteration of the rectouterine pouch. No lesions were observed on the surfaces of the bilateral ovaries, Fallopian tubes, intestines, mesentery, diaphragm, omentum, appendix, stomach, liver, or spleen. The bilateral obturator lymph nodes were enlarged, firm, and approximately 3 cm × 3 cm × 3 cm in size, while the para-aortic lymph nodes measured approximately 3.5 cm × 3.5 cm × 3 cm. The surgical procedures included extrafascial hysterectomy, bilateral salpingo-oophorectomy, omentectomy, resection of enlarged pelvic lymph nodes, para-aortic lymph node dissection (up to the renal vessel level), appendectomy, and optimal cytoreductive surgery (residual tumor classification 0). Fig. 3 Enlarged uterus with multiple nodular lesions on its surface Enlarged uterus with multiple nodular lesions on its surface Postoperative pathology confirmed undifferentiated endometrial carcinoma (UEC) with full-thickness myometrial invasion, involvement of the uterine serosa, extensive lymphovascular invasion, tumor infiltration of the cervical stroma (> two-thirds myometrial depth), lymphovascular invasion extending to the cervical external os stroma, involvement of the right parametrium, and tumor extension to the bladder reflection peritoneum. Multiple pelvic and para-aortic lymph nodes showed metastatic disease (Figs. 4 and 5 ). Fig. 4 Undifferentiated endometrial carcinoma with full-thickness myometrial invasion and involvement of the uterine serosa Fig. 5 Histopathological slide revealing pathological nuclear division and extensive lymphovascular invasion Undifferentiated endometrial carcinoma with full-thickness myometrial invasion and involvement of the uterine serosa Histopathological slide revealing pathological nuclear division and extensive lymphovascular invasion The immunohistochemical findings were as follows: CK7(−), ER(−), PR(−), p16(+), HER2(0), PAX2(−), PAX8(−), PTRK(−), p53 (mutant), MLH1(+), MSH2(+), MSH6(+), PMS2(+), SMARCA4(+), CyclinD1(+), CD34(−), S-100(−), EMA(−), CK5/6(−), and PD-L1 (tumor proportion score [TPS], < 1%; combined positive score [CPS], < 5%) (Fig. 6 ). Fig. 6 Immunohistochemical findings revealing ( A ) p53(+) and ( 6 ) SMARCA4(+) Immunohistochemical findings revealing ( A ) p53(+) and ( 6 ) SMARCA4(+) The surgery proceeded without complications, and the patient recovered satisfactorily, being discharged on the seventh postoperative day with ongoing low-molecular-weight heparin anticoagulation to prevent thrombosis. By postoperative day 20, the patient’s condition had deteriorated sharply, exhibiting symptoms of fever, dyspnea, elevated D-dimer levels (20.39 mg/L), and inflammatory markers (procalcitonin: 0.345 ng/mL, serum amyloid A: > 200 mg/L, C-reactive protein: 106 mg/L), accompanied by pulmonary infection and renal insufficiency (serum creatinine: 314 µmol/L). CT scans revealed multiple pulmonary metastatic lesions and abdominal tumor recurrence with ureteral compression leading to hydronephrosis. Multidisciplinary consultation resulted in treatment with intravenous antibiotics, low-molecular-weight heparin, high-flow oxygen, and bilateral ureteral stent placement. Despite these interventions, the patient’s condition continued to decline, with progressive respiratory failure, and she passed away on postoperative day 26 (Figs. 7 and 8 ). Fig. 7 Computed tomography scans revealing abdominal tumor recurrence with ureteral compression leading to hydronephrosis Fig. 8 Computed tomography scans revealing multiple pulmonary metastatic lesions Computed tomography scans revealing abdominal tumor recurrence with ureteral compression leading to hydronephrosis Computed tomography scans revealing multiple pulmonary metastatic lesions Time Events 28 October 2024 Patient hospitalized 30 October 2024 Surgery 6 November 2024 Discharged from the hospital in stable condition 20 November 2024 Condition progressed 26 November 2024 Patient died

The preoperative diagnosis of UEC is challenging, and most patients require pathological examination after surgical tumor resection for a definitive diagnosis. Patients with advanced UEC have an extremely poor prognosis; even after highly successful surgery, they may die quickly owing to rapid disease progression.

A literature review suggests that preoperative diagnosis of UEC is challenging owing to the absence of specific clinical symptoms, signs, imaging features, or tumor markers, even with diagnostic curettage or hysteroscopic biopsy. A definitive diagnosis necessitates histopathological evaluation of surgically resected specimens, complemented by immunohistochemistry or molecular analysis, and differentiation from neuroendocrine carcinoma, carcinosarcoma, endometrial sarcoma, and other rare tumor types [ 3 , 4 ]. In this instance, preoperative curettage did not indicate malignancy. However, postoperative pathology at our center initially suggested neuroendocrine carcinoma. Following consultation with a pathology professor from the Obstetrics and Gynecology Hospital of Fudan University, the final diagnosis was revised to undifferentiated endometrial carcinoma. The etiology of UEC remains unclear, with its pathogenesis linked to molecular events such as switch/sucrose non-fermentable (SWI/SNF) complex protein inactivation, DNA mismatch repair protein deficiency, POLE gene mutations, and TP53 mutations [ 3 – 5 ]. This patient experienced rapid disease progression, and genetic testing was not performed. Immunohistochemistry indicated intact MMR protein expression, SMARCA4(+), and p53(+). The treatment principles for UEC are similar to those for endometrial cancer. Patients with early stage disease should undergo staging surgery, whereas those with advanced-stage disease should undergo tumor cytoreduction, referencing the surgical scope of ovarian cancer, with the aim of removing as much visible tumor tissue as possible. Patients with advanced-stage disease have an extremely poor prognosis. This particular patient presented with advanced disease; despite successful surgery, the condition progressed rapidly, leading to death in the short term.

Undifferentiated endometrial carcinoma (UEC) is a solid tumor that originates from endometrial epithelial cells, accounting for approximately 9% of endometrial cancers [ 1 ]. UEC lacks morphological evidence of specific epithelial differentiation, exhibits high invasiveness, is often diagnosed at an advanced stage, and demonstrates poor sensitivity to chemotherapy [ 2 ]. The age of onset for UEC is predominantly between 50 and 59 years. Clinical manifestations lack distinct specificity, with the most common symptoms being abnormal uterine bleeding or discharge and lower abdominal pain. In postmenopausal patients, it typically presents as postmenopausal bleeding.

Additional file 1. Additional file 1.