UTROSCT is a specific group of uterine neoplasms with an uncertain histogenesis but with distinct polyphenotypic immunohistochemical expressions. UTROSCT predominantly occur in perimenopausal or menopausal women and there are no specific clinical characteristics for the disease. Most of the patients only present with postmenopausal vaginal bleeding, abnormal menstruation, or pelvic pain[15, 16], with the image results of an enlarged uterus or a uterine mass similar to a uterine fibroid. The tumors generally exhibit intramural, submucous, and subserous masses with pushing or infiltrative borders. There are no specific imaging characters for the diagnosis of the tumors. It is often difficult to make an accurate diagnosis of UTROSCTs before operation or through intraoperative frozen sections because many benign and malignant lesions show similar histopathologic patterns[17]. Usually, the diagnosis of the disease is an incidental discovery on postoperative histopathological analysis. On macroscopic examination, UTROSCT neoplasms usually have a well-defined or slightly irregular margin, yellow or tan color, with a variably soft to firm consistency. Microscopically, the neoplastic cells of UTROSCT are usually small, round or oval, while the cytoplasm of the cells could be scant, moderate, or abundant[1, 18]. They lay out a variety of patterns that simulating ovarian sex cord tumors, appearing the architectures of anastomosing trabeculae, tubules, cords, nests, and Call-Exner–like bodies[15–17, 19–21]. Necrosis and hemorrhage are unusual in UTROSCT. Several recent studies on the polyphenotypic condition of the tumors speculated that the tumors might derivate from ovarian sex cord cells which have been displaced to the uterus during embryogenesis, or pluripotent mesenchymal stem cells[1, 16]. These cells could differentiate into a variety of tissues, and the tumor has a variable IHC profiles with co-expression of epithelial markers (cytokeratin CK, EMA), smooth muscle markers (SMA, Desmin, h-caldesmon), mesenchymal markers (Vimentin), and sex cord markers (α-Inhibin, calretinin, Melan A, CD99, and WT-1) as well as hormonal receptors and miscellaneous markers (ER, PR, CD10, S100)[17, 20].
In the present case, however, the morphology and arrangement of the neoplastic cells conform to UTROSCT, but we found the IHC results of the case were not exactly consistent with previous reports: only one marker for sex-cord tumors was positive (CD99) besides the positive stains of epithelial markers (CK), mesenchymal markers (Vimentin), hormonal receptors (ER and PR). Negative stains for CD10 helped to differentiate from low-grade endometrial stromal sarcoma with sex-cord differentiation[21], negative for HMB-45 was useful to distinguish between UTROSCT and perivascular epithelioid cell neoplasm (PEComa). S100 is usually positively expressed in melanoma or nerve sheath tumors in the uterus and negative stains for it was valuable to rule out these tumors[22]. Krishnamurthy[23] analyzed seven cases and found one or more sex cord markers (α-Inhibin, Melan A, CD99) in addition to variable immunoreactivity for vimentin, estrogen, and progesterone receptors, keratin, actin, and Desmin often strongly suggested a true sex cord differentiation in these tumors. Irving et al[16] concluded that positive expressions for calretinin plus at least 1 of the other three markers (α-Inhibin, Melan A, CD99) might highly reminder the diagnosis of UTROSCT. For this case, the array of architectural patterns for the neoplastic cells is valuable for the diagnosis of UTROSCT. Because of the diagnostic criteria of IHC profiles came from the case reports over the past ten years, we speculate that the results of our case maybe provide a basis for a particular subset of UTROSCT with different pathologic and molecular signatures.
Although the outcomes of the most patients with the tumors generally have a good ending, UTROSCT should be recognized as a definite malignant potential neoplasm because some cases behave with aggressive characters and have the potential of recurrence or extra-uterine spread. To our knowledge, about 21 cases experiencing distant metastasis or recurrence have been reported so far. The metastasis and recurrent sites included lymph nodes, abdominal and pelvic peritoneum and cavity, lung, bones, ovary, liver, and vaginal vault[4, 8, 15, 24]. The recurrence rate of UTROSCT is not clearly specified in the literature. Moore et al[4] observed eight cases with recurrence in 34 cases and calculated a recurrence rate of 23.5% for UTROSCT. Kavneet et al[11] reported that one out of six cases (16.7%) relapsed within 1 year of diagnosis, while Günsu et al[9] reported a recurrence rate was only 6.3%. The reason for the first high percentage rate attributed to the inclusion of patients with metastases or occurrence in other medical institution referred to their institution for consultation which increased the proportion of relapsed patients in the medical institution. The outcomes of the patients with recurrent neoplasm were not always satisfactory, and the mortality rate was 37.5% (3/8) in the manuscript of Moore[4]. Unfortunately, variations in clinical course and the rarity of the cases make it difficult to identify this subset neoplasm with aggressive characters. It seems that none of the tested immunohistochemistry markers were associated with survival outcome, but clinicopathological parameters are a more credible indicator for the clinical prognosis in these tumors. Hauptmann et al[25] concluded that the histological characteristics including pushing versus infiltrative borders, vascular infiltration, and mitotic activity might indicate an aggressive process of a UTROSCT. Moore et al[4] analyzed the clinical materials of 34 case and concluded that older patients, necrosis, lymphovascular invasion (LVSI), cervical involvement, significant nuclear atypia, and significant mitotic activity often exhibited malignant behaviors with a follow-up from 6 to 135 months. However, only necrosis and significant mitotic activity (≥ 2 mitotic figures/10 HPF) were statistically significant for relapse. Michelle et al[7] reported myometrial invasion, serosal involvement, LVSI, and high mitotic activity were present in these aggressive cases of UTROSCT. All three reports mentioned mitotic activity was a possible predictor of an aggressive course. In a further study of 43 cases, large tumors (≥ 10 cm) were associated with an increased risk of cervical/extra-uterine spread[15]. Our results parallel with these results, and we speculated that 6–8 mitotic figures/10 HPF and large tumors (≥ 10 cm) in the primary tumor were of value for the recurrent. The recurrent tumor grew in an infiltrative manner, and the recurrent cells showed a more closely arrangement, more significant atypia, and the addition of rare pseudoglands. The Ki67 index reached from 5% up to 25%. All these pathological characters indicated a high-grade transformation. Furthermore, we found the positive expressions of P53 in the recurrent tumor cells. P53 immunohistochemistry has been believed as an accurate surrogate reflecting the underlying TP53 mutation status of a tumor which often gives rise to the function in promoting tumorigenesis and a more aggressive tumor profile[26, 27]. Due to the long storage time of the paraffin specimen for the primary tumor, we didn’t screen the expression of P53. However, in the recurring tumor, we found that the expression of P53 was positive. We speculate that the role of P53 mutation was not clear in the course of tumor recurrence, but it may be the reason for the increased malignancy of recurring tumors. P53 immunohistochemistry is quite rarely identified in UTROSCT. Among the retrieved articles on UTROSCT, there were 3 articles relevant to the expressions of P53, of which two cases were positive[18, 28] and one case was negative[20]. The two cases with positive stains of P53 both accepted and underwent a hysterectomy with pelvic plus para-aortic lymph node dissection and with no evidence of progressions for a follow-up of 17 months in the second case. It seemed that there was little evidence of the clinical behavior of UTROSCT with P53 mutation. But it might be due to the limited follow-up period and the definite role of P53 in UTROSCT still requires large numbers of cases and follow-up results.
For the treatment of UTROSCT hysterectomy with or without bilateral salpingo-oophorectomy is typically recommended. However, when the tumor occurs in the reproductive age group, a fertility-preserving protocol of resection of the tumor was also reported[29–31]. Some authors also reported cases for conservative surgical approaches obtaining successful pregnancies and deliveries[32]. But the report emphasized the patients for conservative management should have no risk factors for recurrence and recommend careful follow-up. Miho Sato et al[33] reviewed the cases of UTROSCT with malignant behavior and concluded that a radical surgery including bilateral salpingo-oophorectomy, lymphadenectomy, and omentectomy might lead to a lower recurrence rate than a simple hysterectomy alone. Considering the adverse outcome of this case, we wonder whether giving a second-stage surgery or a radical surgery at that time might change the patient’s prognosis.
The limitation of the case report was a lack of molecular analysis. Recently, several series have identified recurring ESR1-NCOA2/3 and GREB1- NCOA1/2 gene fusions in UTROSCT, and recurrences have been documented in a subset of those harboring GREB1 fusions[12, 13, 34]. Instead, we pose that for the recurrent tumor, both the clinical characteristics and the histological morphology of the recurrent neoplastic cells showed a more malignant behavior. In the future, further analyses should be conducted for a better evaluation of UTROSCT with different subtypes, particularly the prognosis, potential treatment, and range of possible molecular events.