Update on pediatric rhabdomyosarcoma: A report from the APSA Cancer Committee

Oncofertility care for children, adolescents, and young adults at risk for treatment-related fertility loss

As therapy for childhood malignancies becomes more sophisticated and survival has improved, long-term therapy-related sequelae have emerged. Loss of reproductive potential among childhood cancer survivors is one such concern that has become increasingly recognized among patients, families, and healthcare providers. The risk status for infertility based upon therapy received, state of current reproductive technology and outcomes, and an emphasis on adequate referral and counseling for fertility preservation options are reviewed. Contributing factors to infertility are discussed, and options for female and male preservation based upon age and pubertal status are summarized. This article highlights the current state of fertility opportunities for children and adolescents undergoing therapy for cancer. Providers caring for these young patients should be familiar with such options and should routinely initiate evaluations for eligibility of fertility preservation.

Roadmap for the next generation of Children's Oncology Group rhabdomyosarcoma trials

Clinical trials conducted by the Intergroup Rhabdomyosarcoma (RMS) Study Group and the Children's Oncology Group have been pivotal to establishing current standards for diagnosis and therapy for RMS. Recent advancements in understanding the biology and clinical behavior of RMS have led to more nuanced approaches to diagnosis, risk stratification, and treatment. The complexities introduced by these advancements, coupled with the rarity of RMS, pose challenges to conducting large-scale phase 3 clinical trials to evaluate new treatment strategies for RMS. Given these challenges, systematic planning of future clinical trials in RMS is paramount to address pertinent questions regarding the therapeutic efficacy of drugs, biomarkers of response, treatment-related toxicity, and patient quality of life. Herein, the authors outline the proposed strategic approach of the Children's Oncology Group Soft Tissue Sarcoma Committee to the next generation of RMS clinical trials, focusing on five themes: improved novel agent identification and preclinical to clinical translation, more efficient trial development and implementation, expanded opportunities for knowledge generation during trials, therapeutic toxicity reduction and quality of life, and patient engagement.

Children's Oncology Group's 2023 blueprint for research: Surgery

Surgery plays a crucial role in the treatment of children with solid malignancies. A well-conducted operation is often essential for cure. Collaboration with the primary care team is important for determining if and when surgery should be performed, and if performed, an operation must be done in accordance with well-established standards. The long-term consequences of surgery also need to be considered. Indications and objectives for a procedure vary. Providing education and developing and analyzing new research protocols that include aims relevant to surgery are key objectives of the Surgery Discipline of the Children's Oncology Group. The critical evaluation of emerging technologies to ensure safe, effective procedures is another key objective. Through research, education, and advancing technologies, the role of the pediatric surgeon in the multidisciplinary care of children with solid malignancies will continue to evolve.

Local Treatment of Children Suffering From Parameningeal Rhabdomyosarcoma: A Retrospective Single-Center Study From China

BACKGROUND

Treatment for parameningeal rhabdomyosarcoma (PM-RMS) has been a challenge since local control is difficult. The goal of this study was to analyse the impact of different local treatment approaches on childhood PM-RMS patients and help dispel the doubt that whether secondary radical surgery (SRS) should be encouraged in the management of PM-RMS.

METHODS

A total of 17 children with PM-RMS who received unified systemic chemotherapy and individualized local therapy such as radiotherapy (RT) and/or SRS were included in this retrospective study. The overall survival (OS) and event free survival (EFS) were compared between groups adopting different local strategies.

RESULTS

The 3-year OS and EFS of our PM-RMS patients was 75.5% and 56.5% respectively. The OS and EFS of patients who received SRS were both significantly lower than that of the non-SRS group (3-year OS: 50.0% vs 90.0%, P = .031; 3-year EFS: 33.3% vs 60.6%, P = .020). The OS and EFS of the patients who received RT was higher than that of the patients of the non-RT group (3-year OS: 85.6% vs 0%, P = .001; 3-year EFS: 64.0% vs 0%, P = .011).

CONCLUSION

This study illustrates that SRS was associated with poor prognosis of PM-RMS and should not be routinely performed. Optimized RT strategies along with more intensive chemotherapy may be alternative options to improve the survival of patients with PM-RMS. Multi-center, large sample and prospective studies are needed to further validate these findings.

An unusual presentation of neonatal rhabdomyosarcoma: a case report

A full-term infant with an unremarkable prenatal course presented at birth with a large midline facial mass and smaller masses in the head and neck. In addition, multiple diffuse flesh-colored nodules spread along all the upper and lower limbs. An extensive evaluation to cover a broad differential diagnosis of infectious, lymphatic/vascular, and oncologic etiology was undertaken. The initial suspicion was confirmed by biopsy of the skin lesion as congenital alveolar rhabdomyosarcoma (RMS). RMS is the most common soft tissue sarcoma that occurs in childhood. However, neonatal RMS is exceedingly rare. The infant's initial treatment included vincristine, dactinomycin, and cyclophosphamide in addition to salvage ifosfamide and etoposide, which were dose-adjusted for age. Herein, we present a case of an infant with RMS who showed initial improvement before relapsing and succumbing to her disease at 5 months of age. A review of the limited literature available on this rare condition and newer treatment regimens with improved mortality rates is performed.

Critical elements of pediatric rhabdomyosarcoma surgery

Rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children, requires multimodal therapy which is determined by risk group stratification. Local control may be achieved by surgical resection, radiation, or both. Resection may occur upfront or following induction chemotherapy as a delayed primary excision. An R1 resection may allow a reduction in radiation exposure; however, debulking is not indicated nor is excision of residual masses at the end of therapy. Regional lymph node assessment is an important component of surgical care, as positive nodal basins require radiation. Depending on the tumor site and biology, sentinel lymph node biopsy vs biopsy of clinically or radiographically concerning nodes is indicated. Therapeutic lymph node dissection is never indicated. Familiarity with site-specific oncologic principles for RMS and participation in a multidisciplinary team including Pediatric Oncology and Radiation Oncology are necessary components of surgical care to ensure optimal outcomes.

Simultaneous diagnosis and resection of orofacial rhabdomyosarcoma with frozen section biopsy: a case report

Rhabdomyosarcoma is the most common soft tissue sarcoma in children, accounting for 4.5% of all cases of cancer in childhood. Although the head and neck are the most common sites of rhabdomyosarcoma, oral lesions are relatively rare and account for only 10% to 12% of head and neck rhabdomyosarcoma cases. This is a case report of a girl aged 2 years and 1 month who initially presented with an upper lip mass that invaded the oral mucosa, oral skin, and nostril skin, causing narrowing of the airway. Through our case, we show that rapidly growing small round cell malignancies, especially rhabdomyosarcoma, can be effectively diagnosed and treated at the same time using primary resection with intraoperative frozen section biopsy and that the time spent waiting for the results of preoperative biopsy can be saved in this way, particularly when the patient's symptoms are intensifying rapidly and require immediate operation.

Pediatric Rhabdomyosarcomas of the Genitourinary Tract

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the pediatric and adolescent population, with 350 new cases diagnosed each year. While they can develop anywhere in the body, the genitourinary tract is the second most common primary location for an RMS to develop. Overall survival has improved through the increased use of protocols and multidisciplinary approaches. However, the guidelines for management continue to change as systemic and radiation therapeutics advance. Given the relative rarity of this disease compared to other non-solid childhood malignancies, healthcare providers not directly managing RMS may not be familiar with their presentation and updated management. This review aims to provide foundational knowledge of the management of RMSs with an emphasis on specific management paradigms for those arising from the genitourinary tract. The genitourinary tract is the second most common location for an RMS to develop but varies greatly in symptomology and survival depending on the organ of origin. As the clinical understanding of these tumors advances, treatment paradigms have evolved. Herein, we describe the breadth of presentations for genitourinary RMSs with diagnostic and treatment management considerations, incorporating the most recently available guidelines and societal consensus recommendations.

Occurrence of Rhabdomyosarcoma After Surgery Combined with oral Sirolimus for Mixed Vascular Malformation of the Tongue

Vascular malformation is the general term of a kind of lesions originated from lymphatic vessels and vascular tissues, which contains a variety of components called mixed vascular malformation. Rhabdomyosarcoma (RMS) is a kind of soft tissue sarcoma, originating from striated muscle cells or mesenchymal cells. RMS and vascular malformation mostly occur in children, and common in the head and neck, but their simultaneous occurrence is rare. A 9-year-old boy who was hospitalized for a second attack of combined vascular malformation: hemolymphangioma. The child experienced severe upper airway obstruction and tongue bleeding. Postoperative pathology demonstrated hemolymphangioma combined with RMS. Subsequently, he was transferred to the oncology department for chemotherapy and lately died of RMS with lung metastasis. The secondary RMS may be related to the usage of sirolimus. Because of its uncertain border, vascular malformation in the oral and maxillofacial region is difficult to completely remove by surgical resection, and local recurrence could be often observed. Due to its rapid progress and continuous bleeding, the possibility of malignant tumor should be considered and multidisciplinary comprehensive treatment should be actively taken. Besides, family history of related malignant tumors and immune function should be investigated in detail before choosing the application of oral sirolimus.

Indocyanine green fluorescence-guided lymphadenectomy with single site retroperitoneoscopy in children

BACKGROUND

Retroperitoneoscopic lymphadenectomy is an established surgical approach in adult urology, but rarely described in pediatric population.

METHODS

We develop retroperitoneoscopic surgical oncology in children, combining new technology innovations in pediatric surgery such as single site port retroperitoneoscopic in supine position and indocyanine green (ICG).

RESULTS

The video describes a step-by-step approach from the ICG injection technique to the lymph-node retroperitoneoscopic harvesting. The video highlights anatomical landmarks and ICG intraoperative lymph nodes findings. Four consecutive surgical procedures were performed in children with paratesticular rhabdomyosarcoma who required staging template retroperitoneal lymph node dissection (RPLND) for staging. All patients were discharged the same day without 30-days postoperative complications.

CONCLUSION

Retroperitoneoscopic approach with single port and indocyanine guided lymphatic mapping for template retroperitoneal lymph node dissection (RPLND) is a feasible minimally invasive procedure in children. Combining different technology innovations allows an effective lymph node harvesting with the possibility to offer an enhanced recovery after surgery in pediatric oncology population.

Imaging in rhabdomyosarcoma: a patient journey

Rhabdomyosarcoma, although rare, is the most frequent soft tissue sarcoma in children and adolescents. It can present as a mass at nearly any site in the body, with most common presentations in the head and neck, genitourinary tract and extremities. The optimal diagnostic approach and management of rhabdomyosarcoma require a multidisciplinary team with multimodal treatment, including chemotherapy and local therapy. Survival has improved over the last decades; however, further improvement in management is essential with current 5-year overall survival ranging from 35% to 100%, depending on disease and patient characteristics. In the full patient journey, from diagnosis, staging, management to follow-up after therapy, the paediatric radiologist and nuclear physician are essential members of the multidisciplinary team. Recently, guidelines of the European paediatric Soft tissue sarcoma Study Group, the Cooperative Weichteilsarkom Studiengruppe and the Oncology Task Force of the European Society of Paediatric Radiology (ESPR), in an ongoing collaboration with the International Soft-Tissue Sarcoma Database Consortium, provided guidance for high-quality imaging. In this educational paper, given as a lecture during the 2022 postgraduate ESPR course, the multi-disciplinary team of our national paediatric oncology centre presents the journey of two patients with rhabdomyosarcoma and discusses the impact on and considerations for the clinical (paediatric) radiologist and nuclear physician. The key learning points of the guidelines and their implementation in clinical practice are highlighted and up-to-date insights provided for all aspects from clinical suspicion of rhabdomyosarcoma and its differential diagnosis, to biopsy, staging, risk stratification, treatment response assessment and follow-up.

Surgical resection of a massive residual retroperitoneal mass after chemotherapy for a paratesticular rhabdomyosarcoma: a case report

INTRODUCTION

Paratesticular rhabdomyosarcoma is a rare and aggressive mesenchymal tumor, accounting for only 7% of all rhabdomyosarcomas. It is mainly encountered in children and adolescents. The standard treatment consists of radical orchidectomy with negative surgical margins. However, chemotherapy is recommended to control retroperitoneal micrometastasis. The place of surgery for progressive retroperitoneal lymph node metastases remains controversial. We present a case of paratesticular rhabdomyosarcoma with progressive retroperitoneal lymph node metastases treated with surgery.

CASE REPORT

We report a case of a 17-year-old North African male with no particular medical history who presented with a left scrotal mass that had been evolving for several months. Beta-human chorionic gonadotropin, alpha-fetoprotein, and lactate dehydrogenase were normal. Scrotal ultrasonography revealed the presence of a 6 cm heterogeneous hypoechogenic tissular mass with cystic areas adherent to the left scrotal wall, which was thickened in some places and vascularized by color Doppler. It exerted a mass effect on the homolateral testicle, which was of average volume. The thoracic-abdominal-pelvic computed tomography scan showed the presence of suspicious paraaortic lymph nodes. The most voluminous one measured 16 × 23 mm². A left orchidectomy was performed. The final pathology report revealed an 8 cm paratesticular rhabdomyosarcoma of the embryonic type that displaced the testicle without invading it. Without going beyond it, it infiltrated the epididymis, the rete testis, and the albuginea. The surgical margin at the level of the spermatic cord was free. The patient had adjuvant chemotherapy (ifosfamide, vincristine, and dactinomycin). The patient had a challenging paraaortic lymph node dissection since the mass enlaced the left ureter and renal vessels. On histological examination, the paraaortic lymph nodes were metastatic.

CONCLUSION

Rhabdomyosarcoma is an aggressive malignancy with high metastatic potential. Therefore, only an accurate diagnosis and early treatment can ensure better survival. Surgery in expert hands seems to be a good option for progressive retroperitoneal nodes. However, further studies are needed to determine the place of surgery in this setting.

Advances in the treatment of pediatric solid tumors: A 50-year perspective

In the United States, more than 10 000 cancers occur annually in children aged 0-14 years, and more than 5000 in adolescents aged 15-19. In the last 50 years, significant advances have been made in imaging, molecular pathology, stage and risk assessment, surgical approach, multidisciplinary treatment, and survival for pediatric solid tumors (particularly neuroblastoma, Wilms tumor, rhabdomyosarcoma, and hepatoblastoma). Moreover, the molecular driver for fibrolamellar hepatocellular carcinoma, which occurs in adolescence and young adulthood, has been identified.

Pearls and updates: cutaneous signs of systemic malignancy

PURPOSE OF REVIEW

Children with systemic malignancies can present with concomitant dermatological manifestations. Cutaneous findings can occur before, during or after diagnosis. Recognizing these features can aid in diagnosis, inform prognosis, and help determine appropriate treatment. Following a review of the literature published over the past two years, we provide an update on cutaneous signs of pediatric systemic malignancies, concentrating on; leukemia cutis, lymphoma cutis, neuroblastoma, sarcomas, Langerhans cell histiocytosis and paraneoplastic syndromes.

RECENT FINDINGS

Authors highlight the persistently heterogeneous features of cutaneous manifestations of systemic malignancy. Findings are often nonspecific, and a definitive diagnosis requires skin biopsy with immunophenotyping. Several studies describe dermoscopy features, demonstrating this as a useful tool in clinical evaluation. Genetic mutations underlying the pathogenesis of disease continue to be elucidated. Further, advances in medical treatment led to improved prognosis in many systemic malignancies, with early and aggressive treatment heralding better outcomes.

SUMMARY

Comprehensive cutaneous evaluation alongside thorough clinical history and review of systems remains of paramount importance as dermatological manifestations of systemic malignancy are notoriously variable with a shared feature of often appearing benign but persisting despite usual treatment. Urgent referral to dermatology is recommended when suspicion for any cutaneous presentation of malignancy arises.

Case Report: Pediatric Hepatic Rhabdomyosarcoma With Maximum Lifetime

Primary intrahepatic rhabdomyosarcoma is an extremely rare malignant tumor. Here, we describe a case of embryonal rhabdomyosarcoma of the liver in a 7-year-old boy without any symptoms. Serologically, the patient showed abnormal levels of serum tumor markers and liver function. Imaging revealed a large mass in the left lobe of the liver and no lesions elsewhere. At first, the patient was misdiagnosed by percutaneous liver biopsy as having clear cell sarcoma. However, the final diagnosis was established to be hepatic embryonal rhabdomyosarcoma based on postoperative histopathology and typical immunohistochemical staining, which was positive for desmin and myogenin. For treatment, the patient received two cycles of preoperative chemotherapy, prophylactic radiotherapy, and 13 cycles of combined postoperative chemotherapy. Routine follow-ups after all treatment conducted by imaging examinations showed no sign of recurrence or metastasis over 13 months, and the patient survives more than 38 months since initial diagnosis. To our knowledge, this patient is the first with hepatic rhabdomyosarcoma to receive neoadjuvant chemotherapy (preoperative chemotherapy) combined with relative comprehensive treatment and achieve a favorable result.

Mitochondrial calcium uptake regulates tumour progression in embryonal rhabdomyosarcoma

Embryonal rhabdomyosarcoma (ERMS) is characterised by a failure of cells to complete skeletal muscle differentiation. Although ERMS cells are vulnerable to oxidative stress, the relevance of mitochondrial calcium homoeostasis in oncogenesis is unclear. Here, we show that ERMS cell lines as well as primary tumours exhibit elevated expression of the mitochondrial calcium uniporter (MCU). MCU knockdown resulted in impaired mitochondrial calcium uptake and a reduction in mitochondrial reactive oxygen species (mROS) levels. Phenotypically, MCU knockdown cells exhibited reduced cellular proliferation and motility, with an increased propensity to differentiate in vitro and in vivo. RNA-sequencing of MCU knockdown cells revealed a significant reduction in genes involved in TGFβ signalling that play prominent roles in oncogenesis and inhibition of myogenic differentiation. Interestingly, modulation of mROS production impacted TGFβ signalling. Our study elucidates mechanisms by which mitochondrial calcium dysregulation promotes tumour progression and suggests that targeting the MCU complex to restore mitochondrial calcium homoeostasis could be a therapeutic avenue in ERMS.

Genitourinary Tract Tumors in Children: An Update

BACKGROUND

Genitourinary tract tumors in children are less common than in adults. Most of these tumors have different genetic backgrounds, clinical presentation, and oncologic behavior than their adult counterpart. As a result of low prevalence in children, some of the treatment approaches and recommendations are based on treatment experience in adult patients. However, thanks to scientific and technological development, survival rates have risen considerably.

OBJECTIVE

This paper presents a review of the principal features of the tumors involving the genitourinary tract in children and an update in genetic background, diagnosis, and treatment.

METHODS

A narrative review was performed on published literature about genitourinary tract tumors in pediatric patients. Papers presented in English and Spanish literature were reviewed. PubMed, Science Direct, and SciELO databases were used to collect information and present this article.

RESULTS

Kidney tumors are the most common type of genitourinary tumors in children. Among those, Wilms tumor represents the majority of cases and shows the successful work of clinical trial groups studying this tumor type. Other tumors involving the genitourinary tract in children include Rhabdomyosarcoma, Transitional cell carcinoma, Testicular, and Adrenal tumors.

CONCLUSION

Genitourinary tract tumors in children represent significant morbidity and economic burden, so awareness in early diagnosis represents improvement in treatment, clinical, and oncological outcomes.

Clinical features and prognosis of paediatric rhabdomyosarcoma with bone marrow metastasis: a single Centre experiences in China

BACKGROUND

The aim of this study was to summarize the clinical characteristics, therapeutic effects and prognosis of patients with rhabdomyosarcoma (RMS) and bone marrow metastasis, improve the understanding of this disease.

METHOD

This was a single-institution retrospective study involving the children with RMS, who presented with bone marrow metastasis at initial presentation to our hospital between 1st, Jan, 2006 and 31st, Dec,2019. Follow-up concluded on 31st, Dec, 2020 and the clinical data were collected and analysed.

RESULT

Between 1st Jan 2006 and 31st Dec 2019, 13 eligible patients presented to our hospital, including 10 males and 3 females, these eligible patients accounted for 4.5% of all RMS patients. The median age at onset was 5.6 years (range 1.7-14 years). The patients not only had unfavourable primary sites, but also had multiple metastases. The bone marrow aspirate samples of the patients comprised 8-95% blast-like cells. Nine of 13 patients were misdiagnosed with haematological malignancies or other solid tumours. With respect to histology, four of 13 children were classified as embryonal RMS and nine as alveolar RMS. Eleven patients underwent PAX-FOXO1 fusion testing; eight had the POX- FOXO1 fusion gene. Immunohistochemically(IHC) analysis revealed that the tumour cells were positive for Desmin, Vimentin, Myo-D1 and Myogenin. More importantly, the patients had extremely poor prognoses, the median EFS was 12.0 months (range 3-28.3 months) and the median OS was 27.0 months (range6-46.2 months).

CONCLUSION

This study demonstrates that children with RMS and bone marrow metastasis usually exhibit atypical primary sites and multiple metastases, with presentation mimicking haematological malignancies or other solid tumors at initial presentation. Pathology and IHC analysis combined with POX-FOXO1 fusion gene detections can effectively confirm the diagnosis. These patients are more likely to relapse or progress during early treatment and are prone to intracranial metastasis. While multidisciplinary therapy combined with Temozolomide may prevent it, further prospective research is required to evaluate the therapeutic effects.

Role of 18F-FDG-PET/CT in the staging of metastatic rhabdomyosarcoma: a report from the European paediatric Soft tissue sarcoma Study Group

BACKGROUND

Initial staging of rhabdomyosarcoma is crucial for prognosis and to tailor the treatment. The standard radiology workup (SRW) includes magnetic resonance imaging, chest computed tomography (CT) and bone scintigraphy, but 18 Fluorine-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) (¹⁸F-FDG-PET/CT (PET-CT)) use is increasing. The aim of this study was to evaluate the impact of PET-CT in the initial staging of patients with metastatic rhabdomyosarcoma enrolled in the European protocol MTS2008.

METHODS

Two authors retrospectively reviewed the SRW and PET-CT reports comparing the number and sites of metastases detected. For bone marrow involvement, PET-CT and bone marrow aspirates/biopsies were compared.

RESULTS

Among 263 metastatic patients enrolled from October 2008 to December 2016, 121 had PET-CT performed at diagnosis, and for 118 of 121 patients, both PET-CT and radiological reports were available for review. PET-CT showed higher sensitivity than SRW in the ability to detect locoregional (96.2% versus 78.5%, P value = 0.0013) and distant lymph node involvement (94.8% versus 79.3%, P value = 0.0242), but sensitivity was lower for intrathoracic sites (lung 79.6% versus 100%, P value = 0.0025). For bone metastasis, PET-CT was more sensitive than bone scintigraphy (96.4% versus 67.9%, P value = 0.0116). The PET-CT sensitivity and specificity to detect marrow involvement were 91.8% and 93.8%, respectively. The mean number of metastatic sites was 1.94 (range 0-5) with PET-CT and 1.72 (range 0-5) with SRW. In four patients (3.4%), PET-CT changed the staging from localised to metastatic disease.

CONCLUSION

PET can identify metastatic disease not evident on SRW in a small number of patients. This is because of its higher ability to recognise lymph node and bone involvement. Chest CT remains essential to detect lesions in intrathoracic sites, which can be performed in a one stop-shot routine examination or on a dedicated chest CT scan. PET-CT could replace bone scintigraphy to study bone involvement.

Head and neck rhabdomyosarcoma with TFCP2 fusions and ALK overexpression: a clinicopathological and molecular analysis of 11 cases

AIMS

Primary intraosseous rhabdomyosarcoma (RMS) is a rare entity defined by EWSR1/FUS-TFCP2 or, less commonly, MEIS1-NCOA2 fusions. The lesions often show a hybrid spindle and epithelioid phenotype, frequently coexpress myogenic markers, ALK, and cytokeratin, and show a striking propensity for the pelvic and craniofacial bones. The aim of this study was to investigate the clinicopathological and molecular features of 11 head and neck RMSs (HNRMSs) characterised by the genetic alterations described in intraosseous RMS.

METHODS AND RESULTS

The molecular abnormalities were analysed with fluorescence in-situ hybridisation and/or targeted RNA/DNA sequencing. Seven cases had FUS-TFCP2 fusions, four had EWSR1-TFCP2 fusions, and none had MEIS1-NCOA2 fusions. All except one case were intraosseous, affecting the mandible (n = 4), maxilla (n = 3), and skull (n = 3). One case occurred in the superficial soft tissue of the neck. The median age was 29 years (range, 16-74 years), with an equal sex distribution. All tumours showed mixed epithelioid and spindle morphology. Immunohistochemical coexpression of desmin, myogenin, MyoD1, ALK, and cytokeratin was seen in most cases. An intragenic ALK deletion was seen in 43% of cases. Regional and distant spread were seen in three and four patients, respectively. Two patients died of their disease.

CONCLUSIONS

We herein present the largest series of HNRMSs with TFCP2 fusions to date. The findings show a strong predilection for the skeleton in young adults, although we also report an extraosseous case. The tumours are characterised by a distinctive spindle and epithelioid phenotype and a peculiar immunoprofile, with coexpression of myogenic markers, epithelial markers, and ALK. They are associated with a poor prognosis, including regional or distant spread and disease-related death.

Pediatric Rhabdomyosarcoma: Epidemiology and Genetic Susceptibility

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in children, yet little is known about its etiology. Studies that examine either environmental exposures or germline genetic predisposition in RMS have begun to identify factors that contribute to this malignancy. Here, we summarize epidemiological reports of RMS incidence in terms of several factors, including age at diagnosis, biological sex, and geographic location. We then describe findings from association studies, which explore the role of parental exposures, birth and perinatal characteristics, and childhood exposures in RMS. Further, we discuss RMS predisposition syndromes and large-scale sequencing studies that have further identified RMS-associated genes. Finally, we propose future directions of study, which aim to advance our understanding of the origin of RMS and can provide knowledge for novel RMS therapies.