The landscape of uterine sarcomas is becoming more complex with the description of new entities associated with recurrent driver molecular alterations. Uterine sarcomas, in analogy with soft tissue sarcomas, are distinguished into complex genomic and simple genomic sarcomas. Leiomyosarcomas and undifferentiated uterine sarcomas belong to complex genomic sarcomas group. Low-grade and high-grade endometrial stromal sarcomas, other rare tumors associated with fusion transcripts (such as NTRK, PDGFB, ALK, RET ROS1) and SMARCA4-deficient uterine sarcoma are considered simple genomic sarcomas. The most common uterine sarcoma are first leiomyosarcoma and secondly endometrial stromal sarcomas. Three different histological subtypes of leiomyosarcoma (fusiform, myxoid, epithelioid) are identified, myxoid and epithelioid leiomyosarcoma being more aggressive than fusiform leiomyosarcoma. The distinction between low-grade and high-grade endometrial stromal sarcoma is primarily morphological and immunohistochemical and the detection of fusion transcripts can help the diagnosis. Uterine PEComa is a rare tumor, which is distinguished into borderline and malignant, according to a risk assessment algorithm. Embryonal rhabdomyosarcoma of the uterine cervix is more common in children but can also occur in adult women. Embryonal rhabdomyosarcoma of the uterine cervix is almost always DICER1 mutated, unlike that of the vagina which is wild-type DICER1, and adenosarcoma which can be DICER1 mutated but with less frequency. Among the emerging entities, sarcomas associated with fusion transcripts involving the NTRK, ALK, PDGFB genes benefit from targeted therapy. The integration of molecular data with histology and clinical data allows better identification of uterine sarcomas in order to better treat them.

OBJECTIVE: Interstitial brachytherapy is indicated as part of a conservative strategy for children with bladder and/or prostate rhabdomyosarcoma (RMS), providing high local control probability with acceptable functional results. Vaginal and/or rectal complications were however reported, due to the close proximity to the implanted volume. We investigated the dosimetric impact of a vaginal spacer in terms of rectal and vaginal doses.
METHODS: Medical records of 12 consecutive female patients with bladder neck RMS, median age 32 months (range: 1.3-6 years), were reviewed. Five patients were treated prior to 2017 without a vaginal spacer and seven patients treated after 2017 had their brachytherapy delivered with a vaginal spacer placed at time of implant.
RESULTS: Minimal doses delivered to the most exposed 2cm3, 1cm3, and 0.5cm3 of the rectum were all statistically significantly lower among patients treated with a vaginal spacer, as compared to those treated without a spacer. Median rectal D2cm3 was 22GyEQD2 versus 38GyEQD2 (P=0.02), D1cm3 was 29GyEQD2 versus 51GyEQD2 (P=0.013), and D0.5cm3 was 32GyEQD2 versus 61GyEQD2 (P=0.017), with and without the vaginal spacer, respectively. The posterior vaginal wall D0.5cm3 dose was also significantly decreased, with median D0.5cm3 of 92GyEQD2 versus 54GyEQD2 (P<0.0001), with and without the spacer, respectively. Acute tolerance was excellent in all patients, with no need for replanning and no acute complication.
CONCLUSIONS: The use of vaginal spacers in brachytherapy of female pediatric patients with bladder neck RMS resulted in significantly decreased doses to the rectum and the posterior vaginal wall. Though the clinical impact of such dose reduction remains undemonstrated, routine utilization of a vaginal spacer could be a method to decrease long-term morbidity in these patients.

Paratesticular Rhabdomyosarcoma accounts for 7 to 11% of pediatric rhabdomyosarcomas. Children older than 10 years have a worse event-free survival (69 to 80% vs. 87 to 92%) than children younger than 10 years. In this location, the relapses are essentially in the retroperitoneal lymph nodes and are often fatal. In European protocols, the assessment of the retroperitoneal lymph nodes at diagnosis is made by imaging whereas it is performed by retroperitoneal lymph node dissection in the American protocols. This method has been proved to improve event-free survival in the group of patient older than 10 years with a tumour bigger than 5cm. In the next European protocol, when nodes will be enlarged a surgical biopsy will be performed, this will be irrespective of age or size, and when no nodes will be enlarged in patients older than 10 years, retroperitoneal lymph node assessment will be performed. Other techniques of lymph nodes assessment will be tested like sentinel node biopsies or PET-scan.

METHODS: Prognostic values of an early detection of a relapse after treatment of a localized rhabdomyosarcoma and the interest of performing systematic radiologic assessment after treatment have not yet been evaluated in Europe.
METHODS: Modalities of relapse of 99 patients under 20 years of age, after an initially localized rhabdomyosarcoma, treated in 9 French centers (\"Société française des cancers de l\'enfant\" consortium) have been analyzed. Prognostic value of the protocol compliance during the observation period after therapy has been evaluated.
RESULTS: Relapses have been diagnosed in 59 cases by a \"symptom\" the child was complaining of, in 12 cases because of \"physical signs\" detected during the clinical examination of a systematic consultation and in 27 cases thanks to \"systematic follow-up imaging\" (missing data: 1 case). Survival after relapse at 3 years was 47.5 % (IC95 %: 37.1 %-57.1 %). Diagnosis of the relapse is established earlier in the group \"systematic imaging\" rather than with other methods of detection (\"symptom\", \"physical signs\"), (P= 0.025), with detection of smaller tumors (≤ 5 cm ; 100.0 % vs. 60.9 % vs. 77.8 %, P= 0.007) but without possibility of reaching a second remission (70.4 % vs. 50.8 % vs. 50.0 % P= 0.37), nor significant impact on 5-year overall survival (47.1 % vs. 47.1 % vs. 48.6 % P= 0.94).
CONCLUSIONS: Current methods of systematic surveillance after a first-line treatment of an initially localized rhabdomyosarcoma seem to improve the earliness of the diagnosis, but not the prognosis of the relapse.

Paratesticular rhabdomyosarcoma is a rare tumor. Multimodality treatment should involve surgery, radiotherapy and chemotherapy, which are indicated according to risk groups. Risk group stratification depends on pretreatment staging and definitive histology. Patients older than 10years or those with suspected lymph nodes on imaging have higher incidence of lymph node involvement. Prognosis is excellent for localized tumors, survival rates exceed 90%. We report a case of embryonal paratesticular rhabdomyosarcoma treated in our institution.