Heterologous and rare homologous sarcomas of the uterine corpus: a clinicopathologic review

Decoding the Molecular Landscape of 262 Uterine Sarcomas: RNA-Seq Clustering of ESS, UTROSCT, and UUS with Prognostic Insights

Low-grade endometrial stromal sarcomas (LG-ESS), high-grade endometrial stromal sarcomas (HG-ESS), undifferentiated uterine sarcomas (UUS), and uterine tumors resembling ovarian sex cord tumors (UTROSCT) are distinct non-smooth muscle cell neoplasms with varying clinical outcomes often exhibiting overlapping characteristics. Diagnosis can be supported by identifying characteristic recurrent translocations, which may be absent in some cases, complicating the distinction of equivocal cases. Additionally, cases with overlapping features of LG and HG characteristics are recognized. To address these challenges, we analyzed RNA-Seq profiles of 262 cases. Our results revealed that LG-ESS, with and without recurrent fusions, clustered into two partially overlapping expression profiles associated with distinct overall and relapse-free survival outcomes, with the cluster containing a majority of fusion-negative tumors demonstrating better prognoses. UTROSCT expression profiles closely resembled those of both LG-ESS subgroups, with NCOA3 fusion-positive cases clustering in groups with better survival outcomes. Furthermore, a distinct cluster for HG-ESS with BCOR and YWHAE fusions was identified, differentiating these tumors from HG-ESS without fusions. ONECUT3 emerged as a potential specific marker for this HG-ESS-fusion entity. A significant expression overlap was observed between monomorphic HG-ESS without fusions and pleomorphic UUS. These samples separated further into two mixed clusters distinguished by differences in immune activity, which significantly influenced overall survival and relapse-free survival outcomes. Unsupervised clustering of UUS revealed subgroups resembling either HG-ESS or muscle-cell differentiated tumors, suggesting that UUS may include poorly differentiated distinct entities, such as leiomyosarcoma, and that the distinction from HG-ESS may, in some cases, be arbitrary. Our transcriptome analysis highlights several entities with distinct survival characteristics, providing a foundation for further characterization of these rare, often difficult-to-classify, tumors.

CD34-positive pleomorphic uterine sarcoma with NUDT3::RAD51B fusion

Sarcomas with RAD51B fusions are rare, recently recognized neoplasms that predominantly arise in the uterus. They showed heterogeneous phenotypic features and are typically associated with aggressive biological behaviors. To date, only 14 cases of RAD51B-rearranged sarcomas have been reported in English literature, including 6 perivascular epithelioid cell tumors, 6 leiomyosarcomas, and 2 undifferentiated sarcomas (both uterine in origin). We present an additional case of uterine sarcoma with RAD51B rearrangement. The patient was a 71-year-old woman with a 5.0-cm polypoid mass in the uterine cavity. Histologically, the tumor was composed of spindle to pleomorphic cells arranged in storiform and fascicular patterns within variably myxoid and collagenous stroma. The neoplastic cells had vesicular to hyperchromatic nuclei with occasional multinucleation, with a mitotic rate of 3/10 high-power fields. Notable stromal features included staghorn shaped blood vessels, thick band-like collagen deposition, and prominent chronic inflammatory infiltrates. Immunohistochemically, the tumor cells showed diffuse and strong positivity for CD34, P53, and P16, with focal expression of pan-TRK and smooth muscle actin. Targeted RNA-sequencing revealed NUDT3::RAD51B fusion, which was confirmed by fluorescence in situ hybridization of RAD51B rearrangement. The patient had been free of disease at 22 months' follow-up. This case further illustrates the phenotypic heterogeneity of RAD51B-rearranged sarcomas and expands their clinicopathological and molecular genetic spectrum.

The Spectrum of Fusions Occurring in Non-Smooth Muscle Mesenchymal Uterine Tumors: A Review of the Current Knowledge

CONTEXT.—

Non-smooth muscle uterine sarcomas are mostly represented by low-grade endometrial stromal sarcoma. However, several other rare, distinct types of uterine sarcoma are recognized, including high-grade endometrial stromal sarcoma, tumors with kinase fusions, uterine tumors resembling ovarian sex cord tumors, soft tissue-type sarcoma, and emerging entities such as KAT6A/B-rearranged tumors. The landscape of uterine sarcomas has changed, mostly because of the increasing knowledge concerning their molecular aberrations.

OBJECTIVE.—

To offer a comprehensive review of the literature focusing on fusions occurring in tumors other than smooth muscle mesenchymal uterine tumors with respect to their type, frequency, and overlap between diagnostic categories and entities.

DATA SOURCES.—

The data were mined from the PubMed/MEDLINE database covering the time period from January 1988 to June 2023. In total, 156 studies focusing on the problematics of fusions occurring in non-smooth muscle mesenchymal uterine tumors were selected, and thus became the basis for this review.

CONCLUSIONS.—

One hundred ten fusions were identified in 703 tumors. The diagnostic significance of the molecular aberrations occurring in these tumors can be unclear in some cases. This can be related to the rare aberrations with a limited number of reported cases. Additionally, even well-known aberrations considered as specific for a certain distinct entity can occur in other lesions, the biological behavior and clinical significance of which can differ substantially.

Metastatic Uterine Leiomyosarcoma With Rhabdomyosarcomatous Heterologous Differentiation

Heterologous differentiation has only been previously reported twice in metastatic uterine leiomyosarcomas. We report herein the first case of metastatic uterine leiomyosarcoma with rhabdomyosarcomatous differentiation. A 67-yr-old woman presented with femur, abductor magnus, and lymph node metastases 9 yr after the primary diagnosis. The metastatic sites showed rhabdomyosarcomatous morphologic features, and immunohistochemical studies confirmed skeletal muscle differentiation. Molecular testing revealed the same loss-of-function TP53 mutation in the uterine leiomyosarcoma and metastatic sites supporting heterologous differentiation of the primary tumor. Our case highlights the morphologic shifts metastatic tumors may manifest and the potential diagnostic problems that may arise.

Cervical leiomyosarcoma in a teenage girl: A rare form of uterine leiomyosarcoma

Sarcomas arising from the cervix are rare, and the reported prevalence is 0.20–0.55%. A 15-year-old Para 0⁺⁰ secondary school student presented to the emergency department in shock with a 1-year history of painless vaginal protrusion, vaginal bleeding, foul-smelling vaginal discharge, occasional passage of blood clots, fatigue, fainting episodes, and weight loss. She was resuscitated with intravenous fluids and blood transfusions. General examination revealed a young girl with a 16-week sized abdominal mass. Vaginal examination revealed a large mobile fleshy mass 14 cm by 10 cm with an offensive discharge and odour. It was externally friable, bled actively on contact, had areas of tissue necrosis, and was oedematous. It was difficult to determine the adnexa structures because of tenderness. Examination under anaesthesia showed that the mass was continuous with the cervix and was not attached to the vagina or vulva. The histology report of the biopsied specimens showed features consistent with cervical leiomyosarcoma (LMS). Cervical LMS was confirmed by immunohistochemistry and a total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed as definitive treatment. Postoperative hormone replacement therapy was initiated. The patient's postoperative condition was stable and there was no tumour recurrence for >2 years on follow-up. Making a diagnosis and instituting surgical and adjuvant treatments for LMS in a low-resource setting are challenging. This is due to lack of access to universal healthcare coverage. A multidisciplinary approach with early diagnosis and complete surgical resection of the tumour provides the most favourable possibility of an improved survival and quality of life.

Characterizing sarcoma dominance pattern in uterine carcinosarcoma: Homologous versus heterologous element

OBJECTIVE

To examine significance of sarcoma dominance (SD) patterns in uterine carcinosarcoma (UCS).

METHODS

This is a secondary analysis of multicenter retrospective study examining women with stages I-IV UCS who underwent primary surgery. SD was defined as >50% of sarcoma component in uterine tumor. SD patterns were grouped as homologous sarcoma without SD (homo/non-dominance, n = 351), heterologous sarcoma without SD (hetero/non-dominance, n = 174), homologous sarcoma with SD (homo/dominance, n = 175), and heterologous sarcoma with SD (hetero/dominance, n = 189), and correlated to tumor characteristics and survival.

RESULTS

SD patterns were significantly associated with age, body habitus, carcinoma type, tumor size, depth of myometrial invasion, and nodal metastasis (all, P < 0.05). On univariate analysis, SD was associated with decreased progression-free survival (PFS) and cause-specific survival (CSS) in homologous cases (both, P < 0.05) but not in heterologous cases. On multivariate models, both homologous and heterologous SD patterns remained independent prognostic factors for decreased PFS (adjusted-hazard ratio [HR] ranges: homo/dominance 1.35-1.69, and hetero/dominance 1.47-1.64) and CSS (adjusted-HR ranges: 1.52-1.84 and 1.66-1.81, respectively) compared to homo/non-dominance (all, P < 0.05). Among stage I-III disease, when tumors had SD, adding radiotherapy to chemotherapy was significantly associated with improved PFS (adjusted-HR: homo/dominance 0.49, and hetero/dominance 0.45) and CSS (0.36 and 0.31, respectively) compared to chemotherapy alone (all, P < 0.05); contrary, this association was not observed with absence of SD (all, P > 0.05).

CONCLUSION

In UCS, SD impacts survival in homologous but not in heterologous type. Regardless of sarcoma types, SD was associated with decreased survival in UCS; adding radiotherapy to chemotherapy may be an effective postoperative strategy.

Dedifferentiated leiomyosarcoma of the uterus with heterologous elements: a potential diagnostic pitfall

Dedifferentiation is a phenomenon that is well characterized in a variety of tumors and is defined by the occurrence of a high-grade or undifferentiated tumor, typically unrecognizable regarding its line of differentiation, from a low-grade/borderline neoplasm. This phenomenon has previously been described in 2 uterine leiomyosarcomas, but both were devoid of heterologous elements. The authors describe herein a case of a dedifferentiated leiomyosarcoma of the uterus with osteoid heterologous elements, believed to be the first such reported case. The original tumor was a high-grade leiomyosarcoma with large low-grade and leiomyoma-like areas and whose constituent cells displayed intense nuclear immunoreactivity for both estrogen receptor (ER) and progesterone receptor (PR) in approximately 30% of cells. The tumor recurred six months after its resection as an undifferentiated sarcoma that was negative for smooth muscle markers, but which remained positive for ER and PR. Osteoid production was only identified in the recurrent tumor and was significant in extent therein. This case highlights the immunophenotypic changes that may occur in dedifferentiated leiomyosarcomas, and this possibility should be a consideration when an apparently undifferentiated sarcoma is identified in a patient with a history of uterine leiomyosarcoma. In our case, the expression of ER and PR provided significant supportive evidence of the uterine origin of the recurrent tumor.