Clinical history and findings
A 46-year-old female patient who had a history of abdominal pain for more than 4 months, with aggravated pain for half a month, went to the hospital. Admission examination: A palpable mass of approximately 20 cm in diameter was found on palpation of the abdomen. The mass was hard, with poor movement, a poor boundary and no tenderness. Total abdominal enhanced computed tomography (CT) showed multiple solid intrapelvic masses with accessory blood supply (FIGURE 1). The patient underwent bilateral resection of pelvic metastases, pelvic adhesions and intestinal adhesions under general anaesthesia.
A 17 cm×13 cm×19 cm solid mass was under the serous membrane of the anterior uterine wall. There was no polyp or mass in the uterine cavity. The thickness of the endometrium was approximately 0.1 cm. The left ovary was enlarged, sized approximately 6 cm×5 cm×3 cm. There was a solid mass of approximately 2.8 cm×2.4 cm×2.2 cm in the left pelvic cavity. The cut surfaces of the masses were grey-white and grey-yellow, with necrosis and cystic changes (FIGURE 1).
The pathological sections were stained with haematoxylin and eosin (H&E) and observed under a microscope. The normal structure of the entire endometrial structure was absent. The endometrial glands could not be observed. Most tumour cells were fusiform and fascicular with abundant eosinophilic cytoplasm, moderate to severe nuclear atypia, coarse chromatin, and prominent nucleoli. Haemorrhage and necrosis (indicative of coagulative necrosis), as well as multinucleated giant cells and vascular infiltration, were obvious (FIGURE 2). There were approximately 11 mitotic figures per 10 high power field (HPF). Sections were diffusely positive for α-smooth muscle actin (α-SMA), Vimentin, Desmin and Wilm’s tumor gene-1 (WT-1) and partly positive for H-Caldesmon, estrogen receptor (ER) and progesterone receptor (PR). The Ki-67 proliferation index was approximately 10% (FIGURE 3). In summary, the diagnosis of leiomyosarcoma was supported by morphology and immunohistochemistry. This tumor accounted for more than 99% of the volume of the mass in the uterine.
The otherwise normal endometrium was replaced by a small portion of round or oval tumor cells that differed from the tumor cells in leiomyosarcoma. Their total volume was less than 1% of leiomyosarcoma. Compared with leiomyosarcoma cells, these tumour cells were larger and more heteromorphic, hyperchromatic and pleomorphic than leiomyosarcoma cells, similar to tumour giant cells, and they had higher mitotic activity (50 MF/10 HPF). Tumour cell necrosis and vascular invasion were visible. Tumour cells had grown diffusely around the thin-walled vasculature (FIGURE 2). The sections were diffusely positive for CD10 and Vimentin, and partly positive for cyclinD1. The Ki-67 proliferation index was approximately 40%. The α-SMA, H-caldesmon, Desmin, WT-1, ER and PR were not expressed (FIGURE 3). The morphology and immunohistochemical results tended to indicate highly malignant ESS. Currently, based on different molecular characteristics, two subtypes of high-grade ESS have been identified: YWHAE-FAM22 gene fusion and BCOR gene alteration. Furthermore, alterations in the YWHAE and BCOR genes (GSP YWHAE and GSP BCOR, Guangzhou LBP Medicine Science and Technology Co., LTD., China) were detected by fluorescence in situ hybridization, which identified BCOR gene alterations but not YWHAE gene alterations. However, the genetic alterations of BCOR or YWHAE were not detected in leiomyosarcoma (FIGURE 4). Therefore, less than 1% of the tumour cells were diagnosed as high-grade ESS with BCOR gene alterations, a newly described subtype of high-grade ESS. More interestingly, the metastases on the left ovary and pelvis showed the same histological morphology and immunophenotype as the high-grade ESS.