Exploring Immunohistochemical Profiling in High-Grade Endometrial Stromal Sarcoma - A Case Study

Abstract Introduction/Objective High grade endometrial stromal sarcoma (HGESS) is a rare and aggressive tumor of endometrial stromal origin comprising about 0.2% of all uterine malignancies. It is often misdiagnosed preoperatively as uterine leiomyoma, leiomyosarcoma or endometrial carcinoma due to lack of well defined clinical and radiological features. We present an unusual case of HGESS with fibroid uterus and abnormal vaginal bleeding. Methods/Case Report A 73-year-old female with a past medical history of uterine fibroids presented with abnormal vaginal bleeding for 6 months. Her MRI uterus revealed enlarged uterus measuring 6.8 X 9.9 X 9.3 cm, multiple fibroids, and endometrial thickness of 4 mm. Hysteroscopic dilation and curettage revealed endometrial polyp and submucosal fibroid. Histopathology of submucosal fibroid revealed loosely cohesive tumor cells with high nuclear/cytoplasmic ratio, scant cytoplasm, and large prominent nucleoli, arranged in solid sheets with myxoid stroma. No glandular formation was identified. Tumor cell necrosis, bizarre tumor cells, and markedly increased mitotic activity, including atypical mitotic figures were present. Immunohistochemistry (IHC) revealed tumor cells diffusely positive for smooth muscle actin, CD10, p53, negative for AE1/AE3, CK7, cam5.2, EMA, ER, PR, desmin, and caldesmon. Ki-67 labels close to 50% of the tumor cells. Combined morphologic and IHC features favored the diagnosis of high-grade sarcoma, including leiomyosarcoma and HGESS. However, the possibility of carcinosarcoma (CS) could not be ruled out. Patient underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy. Final histopathological diagnosis revealed HGESS, pT1b. Lack of carcinomatous component and negative IHC staining for CK7, CAM 5.2, AE1/AE3 ruled out CS. IHC showed tumor cells diffusely positive for CD10, actin, desmin and CD 56, focally positive for caldesmon, cyclin D1 and CD 117 and negative for DOG 1, further supporting the diagnosis for HGESS over leiomyosarcoma. Results (if a Case Study enter NA) NA Conclusion Definitive diagnosis of HGESS is achieved through histology and IHC. An appropriate panel of IHC markers is essential to differentiate between endometrial stromal tumors from leiomyosarcoma and CS. Accurate diagnose of this rare clinical entity is critical especially in its initial stages owing to its poor prognosis and aggressive nature.