Classification of rhabdomyosarcomas and related sarcomas. Pathologic aspects and proposal for a new classification--an Intergroup Rhabdomyosarcoma Study

Genomic profiling of pleomorphic rhabdomyosarcoma reveals a genomic signature distinct from that of embryonal rhabdomyosarcoma

Pleomorphic rhabdomyosarcoma (PRMS) is a rare and highly aggressive sarcoma, occurring mostly in the deep soft tissues of middle-aged adults and showing a variable degree of skeletal muscle differentiation. The diagnosis is challenging as pathologic features overlap with embryonal rhabdomyosarcoma (ERMS), malignant Triton tumor, and other pleomorphic sarcomas. As recurrent genetic alterations underlying PRMS have not been described to date, ancillary molecular diagnostic testing is not useful in subclassification. Herein, we perform genomic profiling of a well-characterized cohort of 14 PRMS, compared to a control group of 23 ERMS and other pleomorphic sarcomas (undifferentiated pleomorphic sarcoma and pleomorphic liposarcoma) using clinically validated DNA-targeted Next generation sequencing (NGS) panels (MSK-IMPACT). The PRMS cohort included eight males and six females, with a median age of 53 years (range 31-76 years). Despite similar tumor mutation burdens, the genomic landscape of PRMS, with a high frequency of TP53 (79%) and RB1 (43%) alterations, stood in stark contrast to ERMS, with 4% and 0%, respectively. CDKN2A deletions were more common in PRMS (43%), compared to ERMS (13%). In contrast, ERMS harbored somatic driver mutations in the RAS pathway and loss of function mutations in BCOR, which were absent in PRMS. Copy number variations in PRMS showed multiple chromosomal arm-level changes, most commonly gains of chr17p and chr22q and loss of chr6q. Notably, gain of chr8, commonly seen in ERMS (61%) was conspicuously absent in PRMS. The genomic profiles of other pleomorphic sarcomas were overall analogous to PRMS, showing shared alterations in TP53, RB1, and CDKN2A. Overall survival and progression-free survival of PRMS were significantly worse (p < 0.0005) than that of ERMS. Our findings revealed that the molecular landscape of PRMS aligns with other adult pleomorphic sarcomas and is distinct from that of ERMS. Thus, NGS assays may be applied in select challenging cases toward a refined classification. Finally, our data corroborate the inclusion of PRMS in the therapeutic bracket of pleomorphic sarcomas, given that their clinical outcomes are comparable.

Embryonal and alveolar rhabdomyosarcoma in adolescents/young adults, adults and older adults: a population-based cohort study

BACKGROUND

The clinical characteristics, outcomes, and prognostic factors of adult embryonal rhabdomyosarcomas (ERMS) and alveolar rhabdomyosarcomas (ARMS), particularly the differences among adolescents/young adults (AYA), adults, and older adults, remain unclear. We assessed the clinicopathological features and survival outcomes of adult patients with ERMS and ARMS in Japan and to compare these features among AYA, adult, and older adult patients.

METHODS

We retrospectively analyzed data from the Bone and Soft Tissue Tumor Registry of Japan and enrolled patients aged ≥15 years with ERMS and ARMS. Disease-specific overall survival (DOS) was estimated using the Kaplan-Meier method, and a Cox regression model was used to identify prognostic factors.

RESULTS

Among 184 patients with ERMS and ARMS (median age, 27 years; interquartile range, 18-49 years), a high rate of distant and regional nodal metastases was initially observed in 65 (35%) and 66 (36%) cases, respectively. Older age and distant metastasis at first presentation were statistically poor prognostic factors, and histological subtype and site of tumor origin were not associated with DOS. In patients with localized ERMS and ARMS, older age and nodal metastasis were poor prognostic factors; the 5-year DOS rates of patients with and without nodal metastasis were 23% and 72%, respectively.

CONCLUSIONS

Older patients with rhabdomyosarcoma had a dismal prognosis, and distant metastasis was a poor prognostic factor. The prognostic factors differed between adult and pediatric patients with rhabdomyosarcoma; biological analyses, such as genome analysis of adult rhabdomyosarcoma and clinical trials with pediatric oncologists, are needed to improve the prognosis of adult rhabdomyosarcoma.

Adult head and neck rhabdomyosarcoma: radiotherapy- based treatment, outcomes, and predictors of survival

BACKGROUND

Adult head and neck rhabdomyosarcoma (HNRMS) is an exceptionally rare malignancy, and there is a paucity of data and research dedicated to understanding its characteristics and management in adult populations. This study aimed to assess the outcomes and identify survival predictors in adult HNRMS.

METHODS

We retrospectively evaluated 42 adult patients (> 16 years) with HNRMS who received radiotherapy (RT)-based treatment at our institute between 2008 and 2022. We analysed the clinical characteristics and prognosis of these patients, including the locoregional recurrence-free survival (LRFS), progression-free survival (PFS), and overall survival (OS), using the Kaplan-Meier method. The chi-square and Fisher's exact tests were used to analyse differences between groups for dichotomous and categorical variables, respectively. Survival rates were calculated using the Kaplan-Meier method. Prognostic variables were assessed through univariate Cox analyses.

RESULTS

The median patient age was 28 years (range, 16-82 years). Alveolar RMS was the most common histological type, observed in 21 patients (50.0%), followed by embryonal in 16 patients (38.1%). The anatomic sites of origin were orbital in one (2.4%), parameningeal in 26 (61.9%), and non-orbital/non-parameningeal in 15 (35.7%) patients. Nineteen patients (45.2%) had regional lymph node metastasis, and five patients (11.9%) presented with distant metastatic disease. Distant metastasis (n = 17) was the primary cause of treatment failure. At a median follow-up of 47.0 months, the 5-year LRFS, PFS, and OS rates were 69.0%, 39.7%, and 41.0%, respectively. Univariate analysis revealed that tumour size, lymph node involvement, and the local treatment pattern (surgery and RT vs. RT alone) were significant predictors of survival.

CONCLUSIONS

The main failure pattern in patients with HNRMS receiving RT-based treatment was distant metastasis. Tumour size > 5 cm and lymph node involvement were predictors of worse LRFS. Multimodality local treatment, combining surgery and RT, is effective and provides survival benefits.

Pediatric, adolescent, and young adult breast and reproductive tumors

Tumors of the breast and reproductive organs that occur in children, adolescents, and young adults (AYA) have different biological features and can present special challenges. Although prognosis for these tumors is generally favorable, the long-term effects of treatment can be debilitating. Treatments are often multimodal and may include surgery as well as chemotherapy and/or radiation, which can cause considerable distress and anxiety related to loss of femininity or masculinity, concern over future fertility, or sexual dysfunction. Thus, tumors of the reproductive organs in pediatric/AYA patients require special consideration of the treatment effects beyond the intended oncologic outcome. Multidisciplinary teams should be involved in their care and address issues of fertility, sexual dysfunction, and psychosexual concerns before treatment begins. This review addresses histology, risk factors, prognosis, staging and treatment of gynecologic, breast and testicular cancers in pediatric and AYA patients.

Spindle Cell Rhabdomyosarcoma of the Inguinal Region Mimicking a Complicated Hernia in the Adult-An Unexpected Finding

Rhabdomyosarcoma is a rare tumor that is diagnosed mostly in children and adolescents, rarely in adults, representing 2-5% of all soft tissue sarcomas. It has four subtypes that are recognized: embryonal (50%), alveolar (20%), pleomorphic (20%), and spindle cell/sclerosing (10%). The diagnosis of rhabdomyosarcoma is based on the histological detection of rhabdomyoblasts and the expression of muscle-related biomarkers. Spindle cell/sclerosing rhabdomyosarcoma consists morphologically of fusiform cells with vesicular chromatin arranged in a storiform pattern or long fascicles, with occasional rhabdomyoblasts. Also, dense, collagenous, sclerotic stroma may be seen more commonly in adults. We present a rare case of an adult who presented to the hospital with a tumor in the left inguinal area, was first diagnosed with a left strangulated inguinal hernia and was operated on as an emergency, although the diagnosis was ultimately a spindle cell rhabdomyosarcoma of the inguinal region.

Biological Role and Clinical Implications of MYOD1L122R Mutation in Rhabdomyosarcoma

Major progress in recent decades has furthered our clinical and biological understanding of rhabdomyosarcoma (RMS) with improved stratification for treatment based on risk factors. Clinical risk factors alone were used to stratify patients for treatment in the European Pediatric Soft Tissue Sarcoma Study Group (EpSSG) RMS 2005 protocol. The current EpSSG overarching study for children and adults with frontline and relapsed rhabdomyosarcoma (FaR-RMS NCT04625907) includes FOXO1 fusion gene status in place of histology as a risk factor. Additional molecular features of significance have recently been recognized, including the MYOD1^L122R gene mutation. Here, we review biological information showing that MYOD1^L122R blocks cell differentiation and has a MYC-like activity that enhances tumorigenesis and is linked to an aggressive cellular phenotype. MYOD1^L122R mutations can be found together with mutations in other genes, such as PIK3CA, as potentially cooperating events. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, ten publications in the clinical literature involving 72 cases were reviewed. MYOD1^L122R mutation in RMS can occur in both adults and children and is frequent in sclerosing/spindle cell histology, although it is also significantly reported in a subset of embryonal RMS. MYOD1^L122R mutated tumors most frequently arise in the head and neck and extremities and are associated with poor outcome, raising the issue of how to use MYOD1^L122R in risk stratification and how to treat these patients most effectively.

Sarcoma Botryoides: Optimal Therapeutic Management and Prognosis of an Unfavorable Malignant Neoplasm of Female Children

Embryonal rhabdomyosarcoma (ERMS) is a rare malignancy and occurs primarily in the first two decades of life. Botryoid rhabdomyosarcoma is an aggressive subtype of ERMS that often manifests in the genital tract of female infants and children. Due to its rarity, the optimal treatment approach has been a matter of debate. We conducted a search in the PubMed database and supplemented it with a manual search to retrieve additional papers eligible for inclusion. We retrieved 13 case reports and case series, from which we summarized that the current trend is to approach each patient with a personalized treatment plan. This consists of a combination of local debulking surgery and adjuvant or neoadjuvant chemotherapy (NACT). Effort is made in every approach to avoid radiation for the sake of preserving fertility. Radical surgeries and radiation still have a role to play in extensive disease and in cases of relapse. Despite the rarity and aggressiveness of this tumor, disease-free survival and overall prognosis is excellent, especially when it is diagnosed early, compared with other subtypes of rhabdomyosarcoma (RMS). We conclude that the practice of a multidisciplinary approach is appropriate, with favorable outcomes; however, larger-scale studies need to be organized to have a definite consensus on optimal management.

Non-inferior efficacy of non-surgical treatment to surgical treatment in patients with nonmetastatic head and neck rhabdomyosarcoma: a SEER-based study

PURPOSE

Head and neck rhabdomyosarcoma (HNRMS) is a rare but aggressive malignant neoplasm. Given the young patient age and critical anatomy of the head and neck, performing surgery on the primary tumor still remains debatable. This study aimed to evaluate the impact of the non-surgery-based treatment versus surgery-based treatment on patients with nonmetastatic HNRMS.

METHODS

Patients diagnosed with nonmetastatic HNRMS between 2004 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database were enrolled in our study. Inverse probability treatment weighting (IPTW) method was employed to balance confounding factors between surgery and non-surgery groups. Kaplan-Meier methods and COX regression analyses were used to analyze survival outcomes of overall survival (OS) and cancer-specific survival (CSS). Prognostic nomogram was established to predict survival.

RESULTS

A total of 260 eligible patients were extracted from the SEER database. Kaplan-Meier survival curves revealed that there was no significant difference in OS and CSS between the surgery and non-surgery groups both before and after IPTW (p > 0.05). Cox regression analyses and IPTW-adjusted Cox regression analyses for both OS and CSS showed similar survival between the two groups. Prognostic factors were explored and a nomogram for patients in the surgery group was constructed. Risk stratification based on the nomogram indicated that patients in surgery-high-risk group did not benefit from primary surgery. While those in surgery-low-risk group had an equal survival outcome to those in non-surgery group.

CONCLUSIONS

Our study revealed that compared to patients receiving surgery, those not receiving surgery had similar survival outcomes for nonmetastatic HNRMS. Our established nomogram may serve as a practical tool for individual prognostic evaluations.

Perianal/perineal rhabdomyosarcoma: Results of the SIOP MMT 95, Italian RMS 96, and EpSSG RMS 2005 studies

BACKGROUND/OBJECTIVES

Rhabdomyosarcoma of the perianal/perineal region (PRMS) is rare, with poor survival and limited understanding of the functional consequences of treatment.

DESIGN/METHODS

International Society of Pediatric Oncology (SIOP) malignant mesenchymal tumor (MMT) 95, Italian RMS 96, and European paediatric Soft tissue sarcoma Study Group (EpSSG) RMS 2005 studies were interrogated to identify factors that impact survival; in RMS 2005, functional outcomes were analyzed.

RESULTS

Fifty patients (nonmetastatic) were identified, median age 6.4 years (range: 0.1-19.6): 29 male, 21 female. Tumors were >5 cm in 33 patients. Histopathological subtype was alveolar in 35. Lymph nodes were involved in 23 patients. In RMS 2005, 16/21 (76%) tested alveolar tumors had positive FOXO1 fusion status. Diagnostic biopsy was performed in 37. Primary resection (13) was complete (R0) in one. Delayed primary excision (16) was complete in three. Radiotherapy (RT) in 34/50 patients included external beam (28), brachytherapy (3), and both (3). Nodal RT was given in 16/23 N1 patients (70%). Median follow-up of alive patients (29) was 84.1 months (range: 3.6-221.1). Relapse or progression occurred in 24 patients (48%), 87% were fatal and most events (63%) were locoregional. Five-year event-free survival (EFS) was 47.8 (95% CI: 32.8-61.3), and 5-year overall survival (OS) was 52.6 (95% CI: 36.7-66.2), with age ≥10 years and tumor size >5 cm impacting 5-year EFS and OS (p < .05). Functional outcome data showed bowel, genito-urinary, and psychological issues; fecal incontinence in four of 21 survivors, and urinary symptoms in two of 21.

CONCLUSIONS

About 60% of patients with nonmetastatic PRMS survive; older patients and those with large tumors have the worst outcomes. Biopsy should be the initial procedure, and definitive local therapy individualized. Quality-of-life and functional studies are needed to better understand the consequences of treatment.

Deep Learning of Rhabdomyosarcoma Pathology Images for Classification and Survival Outcome Prediction

Rhabdomyosarcoma (RMS), the most common malignant soft tissue tumor in children, has several histologic subtypes that influence treatment and predict patient outcomes. Assistance with histologic classification for pathologists as well as discovery of optimized predictive biomarkers is needed. A convolutional neural network for RMS histology subtype classification was developed using digitized pathology images from 80 patients collected at time of diagnosis. A subsequent embryonal rhabdomyosarcoma (eRMS) prognostic model was also developed in a cohort of 60 eRMS patients. The RMS classification model reached a performance of an area under the receiver operating curve of 0.94 for alveolar rhabdomyosarcoma and an area under the receiver operating curve of 0.92 for eRMS at slide level in the test data set (n = 192). The eRMS prognosis model separated the patients into predicted high- and low-risk groups with significantly different event-free survival outcome (likelihood ratio test; P = 0.02) in the test data set (n = 136). The predicted risk group is significantly associated with patient event-free survival outcome after adjusting for patient age and sex (predicted high- versus low-risk group hazard ratio, 4.64; 95% CI, 1.05-20.57; P = 0.04). This is the first comprehensive study to develop computational algorithms for subtype classification and prognosis prediction for RMS histopathology images. Such models can aid pathology evaluation and provide additional parameters for risk stratification.

Long-Term Clinical Outcome and Prognostic Factors of Children and Adolescents with Localized Rhabdomyosarcoma Treated on the CWS-2002P Protocol

We report here the results of the prospective, non-randomized, historically controlled CWS-2002P study in patients ≤ 21 years with localized RMS developed with the aim to improve the long-term outcome by adapting the burden of therapy to risk profile and to investigate the feasibility and relation to the outcome of maintenance therapy (MT) in the high-risk groups. Patients were allocated into low-risk (LR), standard-risk (SR), high-risk (HR), and very high-risk (VHR) groups. Chemotherapy consisted of vincristine (VCR) and dactinomycin (ACTO-D) for all patients with the addition of ifosfamide (IFO) in the SR, HR, and VHR and doxorubicin (DOX) in the HR and VHR groups. Low-dose cyclophosphamide and vinblastine maintenance therapy (MT) over 6 months was recommended in the HR and VHR groups. A total of 444 patients have been included in this analysis. With a median follow-up of 9·6 years (IQR 7·6–10·9) for patients alive, the 5-year EFS and OS for the whole group was 73% (95% CI 69–77) and 80% (95% CI 76–84), respectively. The 5-year EFS by risk group was 100% in the LR, 79% (95% CI 72–84) in the SR, 69% (95% CI 63–75) in the HR, and 42% (95% CI 23–61) in the VHR (log-rank p = 0.000). The 5-year EFS was 77% (95% CI 70–84%) for 155 patients in the HR group who received MT as compared to 63% (95% CI 50–76) for 49 patients who did not (log-rank p = 0.015). Neither the reduction in the IFO dose in the SR nor the increased dose intensity of DOX in HR groups influenced the outcome when compared to the previous CWS and other European studies. MT was feasible, seemed to have an impact on prognosis, and should be studied in a well-controlled prospective trial in this patient population. The weighting of risk factors used for therapy stratification needs to be reevaluated.

Spindle cell rhabdomyosarcoma in the adult: A rare case report

Spindle cell/sclerosing rhabdomyosarcoma (RMS) is an uncommon type of RMS and has been classified as a separate entity by the WHO in 2013. It affects both children and adults with a greater incidence in males. These tumors can pose a diagnostic challenge and can be difficult to differentiate from other spindle cell malignant tumors in the head and neck. Here, we report a case of spindle cell/sclerosing RMS in a young woman presenting with a swelling on the left side of the face of 3 months duration. A careful correlation with the radiographic images, histopathological findings and immunohistochemistry helped to arrive at a diagnosis.

An Integrative Morphologic and Molecular Approach for Diagnosis of Rhabdomyosarcoma and Subclassification of Rhabdomyosarcoma

CONTEXT.—

Rhabdomyosarcoma, the most common soft tissue sarcoma of children, is currently classified into the following 4 subtypes: embryonal rhabdomyosarcoma, alveolar rhabdomyosarcoma, spindle cell/sclerosing rhabdomyosarcoma, and pleomorphic rhabdomyosarcoma, based on recent molecular genetic knowledge and morphologic features.

OBJECTIVE.—

To highlight the most recent advances of molecular genetic alterations, and to familiarize pathologists with most recent genotype and phenotype correlation in rhabdomyosarcoma.

DATA SOURCES.—

Data were derived from the World Health Organization Classification of Soft Tissue and Bone Tumors, fifth edition, recently published literature (PubMed), and clinical practice experience.

CONCLUSIONS.—

Current classification has been significantly impacted by genotype and phenotype correlation, especially with PAX-FOXO1 fusion-positive rhabdomyosarcoma versus fusion-negative rhabdomyosarcoma, and with emergence of 3 distinct new subtypes of spindle cell/sclerosing rhabdomyosarcoma. Although all rhabdomyosarcomas were considered to be a single diagnostic entity in the past, they are now considered to be a group of histologically similar but biologically diverse entities because their clinical behavior and underlying molecular alterations dramatically differ. This review outlines recent molecular genetic developments, corresponding morphologic features, and current challenges faced by pathologists in daily practice.

Functional impact and targetability of PI3KCA, GNAS, and PTEN mutations in a spindle cell rhabdomyosarcoma with MYOD1 L122R mutation

Spindle cell/sclerosing rhabdomyosarcoma (ssRMS) is a rare subtype of rhabdomyosarcoma, commonly harboring a gain-of-function L122R mutation in the muscle-specific master transcription factor MYOD1. MYOD1-mutated ssRMS is almost invariably fatal, and development of novel therapeutic approaches based on the biology of the disease is urgently needed. MYOD1 L122R affects the DNA-binding domain and is believed to confer MYC-like properties to MYOD1, driving oncogenesis. Moreover, the majority of the MYOD1-mutated ssRMS harbor additional alterations activating the PI3K/AKT pathway. It is postulated that the PI3K/AKT pathway cooperates with MYOD1 L122R. To address this biological entity, we established and characterized a new patient-derived ssRMS cell line OHSU-SARC001, harboring MYOD1 L122R as well as alterations in PTEN, PIK3CA, and GNAS. We explored the functional impact of these aberrations on oncogenic signaling with gain-of-function experiments in C2C12 murine muscle lineage cells. These data reveal that PIK3CA^I459_T462del, the novel PIK3CA variant discovered in this patient specimen, is a constitutively active kinase, albeit to a lesser extent than PI3KCA^E545K, a hotspot oncogenic mutation. Furthermore, we examined the effectiveness of molecularly targeted PI3K/AKT/mTOR and RAS/MAPK inhibitors to block oncogenic signaling and suppress the growth of OHSU-SARC001 cells. Dual PI3K/mTOR (LY3023414, bimiralisib) and AKT inhibitors (ipatasertib, afuresertib) induced dose-dependent reductions in cell growth. However, mTOR-selective inhibitors (everolimus, rapamycin) alone did not exert cytotoxic effects. The MEK1/2 inhibitor trametinib did not impact proliferation even at the highest doses tested. Our data suggest that molecularly targeted strategies may be effective in PI3K/AKT/mTOR-activated ssRMS. Taken together, these data highlight the importance of utilizing patient-derived models to assess molecularly targetable treatments and their potential as future treatment options.

Evolving classification of rhabdomyosarcoma

Rhabdomyosarcomas comprise the single largest category of soft tissue sarcomas in children and adolescents in the United States, occurring in 4.5 million people aged below 20 years. Based on the clinicopathological features and genetic abnormalities identified, rhabdomyosarcomas are classified into embryonal, alveolar, spindle cell/sclerosing and pleomorphic subtypes. Each subtype shows distinctive morphology and has characteristic genetic abnormalities. This review discusses the evolution of the classification of rhabdomyosarcoma to the present day, together with a discussion of key histomorphological and genetic features of each subtype and the diagnostic approach to these tumours.

MYOD1 as a prognostic indicator in rhabdomyosarcoma

BACKGROUND/OBJECTIVES

Rhabdomyosarcoma (RMS) is characterized by the expression of the myogenic regulatory protein MYOD1. Histologic types include alveolar, embryonal (ERMS), and spindle cell sclerosing RMS (SRMS). SRMS harbors MYOD1 mutations in a subset of adult cases in association with poor prognosis.

DESIGN/METHODS

To study the level of MYOD1 protein expression and its clinical significance, we have analyzed variable numbers of pediatric (<18 years of age) and adult (age range ≥18 to 35 years) ERMS and SRMS cases for presence or absence of MYOD1 immunoreactivity in correlation with clinical outcome and MYOD1 L122R mutations.

RESULTS

Lack of MYOD1 immunoreactivity, identified in 23.8% of nonalveolar RMS (non-ARMS) cases, was more prevalent in SRMS (44%) than ERMS (17.2%) and was significantly associated with low overall survival and unfavorable tumor sites (p < .05). Lack of MYOD1 immunoreactivity was not associated with MYOD1 L122R mutations, which were identified in 3/37 (8%) cases including only two of 31 (6.5%) pediatric cases, one of 11 or 9% pediatric SRMS, and one case of infant ERMS.

CONCLUSION

These studies highlight the prognostic role of MYOD1 in non-ARMS. Lack of MYOD1 immunoreactivity is associated with poor prognosis in ERMS and SRMS. MYOD1 gene mutations are generally infrequent in pediatric RMS. Although mutations are predominant in SRMS, they may exceptionally occur in infantile ERMS.

Clinicopathologic and molecular analysis of embryonal rhabdomyosarcoma of the genitourinary tract: evidence for a distinct DICER1-associated subgroup

Embryonal rhabdomyosarcoma (ERMS) of the uterus has recently been shown to frequently harbor DICER1 mutations. Interestingly, only rare cases of extrauterine DICER1-associated ERMS, mostly located in the genitourinary tract, have been reported to date. Our goal was to study clinicopathologic and molecular profiles of DICER1-mutant (DICER1-mut) and DICER1-wild type (DICER1-wt) ERMS in a cohort of genitourinary tumors. We collected a cohort of 17 ERMS including nine uterine (four uterine corpus and five cervix), one vaginal, and seven urinary tract tumors. DNA sequencing revealed mutations of DICER1 in 9/9 uterine ERMS. All other ERMS of our cohort were DICER1-wt. The median age at diagnosis of patients with DICER1-mut and DICER1-wt ERMS was 36 years and 5 years, respectively. Limited follow-up data (available for 15/17 patients) suggested that DICER1-mut ERMS might show a less aggressive clinical course than DICER1-wt ERMS. Histological features only observed in DICER1-mut ERMS were cartilaginous nodules (6/9 DICER1-mut ERMS), in one case accompanied by foci of ossification. Recurrent mutations identified in both DICER1-mut and DICER1-wt ERMS affected KRAS, NRAS, and TP53. Copy number analysis revealed similar structural variations with frequent gains on chromosomes 2, 3, and 8, independent of DICER1 mutation status. Unsupervised hierarchical clustering of array-based whole-genome DNA methylation data of our study cohort together with an extended methylation data set including different RMS subtypes from genitourinary and extra-genitourinary locations (n = 102), revealed a distinct cluster for DICER1-mut ERMS. Such tumors clearly segregated from the clusters of DICER1-wt ERMS, alveolar RMS, and MYOD1-mutant spindle cell and sclerosing RMS. Only one tumor, previously diagnosed as ERMS arising in the maxilla of a 6-year-old boy clustered with DICER1-mut ERMS of the uterus. Subsequent sequencing analysis identified two DICER1 mutations in the latter case. Our results suggest that DICER1-mut ERMS might qualify as a distinct subtype in future classifications of RMS.

[Diagnostics of benign and malignant tumors of the orbit]

BACKGROUND

Orbital space-occupying lesions can have a significant impact on the quality of life. Depending on the dignity and etiology of the mass, they can even represent a life-threatening process, which must be timely treated in an interdisciplinary cooperation.

OBJECTIVE

To achieve a comprehensive overview about the diagnostics and frequency of malignant and benign masses of the orbit.

MATERIAL AND METHODS

A literature search was carried out in PubMed and Google scholar.

RESULTS AND DISCUSSION

Clinically, orbital lesions can show symptoms, such as exophthalmos with an increase in the vertical lid fissure, visual impairment and motility dysfunction with diplopia. Depending on the extent, an exposure keratopathy can occur due to failure to close the eyelids. For the diagnostics several tests should be carried out. Following a thorough anamnesis and clinical examination, these should include a blood sample to test for various parameters, an ultrasound examination with subsequent computed tomography (CT) in cases of bone involvement or thin slice magnetic resonance imaging (MRI) of the orbit for assessment of soft tissues. In adults an endocrine orbitopathy is the most frequent cause of an inflammatory orbital process, where lymphomas are the most frequent entity among malignant tumors and vascular space-occupying lesions are the most frequent benign tumors. In children the most frequent benign masses are dermoid cysts and rhabdomyosarcoma is the most frequent primary malignant orbital tumor. The multimodal interdisciplinary treatment can include surgical excision and adjuvant radiotherapy or chemotherapy, depending on the entity.

Changes in FXR1 expression after Chemotherapy for Rhabdomyosarcoma

BACKGROUND

Rhabdomyosarcoma (RMS) arises from abnormal muscle development. We reported previously that Fragile-X-Related 1 (FXR1), essential to normal myogenesis, was highly expressed in RMS relative to other embryonal tumors. This current study explored FXR1 expression across RMS disease characteristics and treatment response.

METHODS

RMS patients ≤18 years (1980-2019; n = 152) were categorized according to tumor histology, PAX/FOXO1 translocation, and vital status. FXR1 protein expression was compared before and after chemotherapy. Impact of FXR1 expression on relapse-free (RFS) and overall survival (OS) was analyzed.

RESULTS

FXR1 was most intensely expressed in the cytosol of undifferentiated rhabdomyoblasts. At diagnosis, FXR1 expression was ubiquitous and strong across all disease characteristics and foremost associated with worse RFS in translocation-positive patients (p = 0.0411). Among embryonal and translocation-negative RMS, survivors showed a significantly greater decrease in FXR1 expression after chemotherapy (p < 0.001) compared to decedents (p = 0.8). In contrast, alveolar and translocation-positive RMS specimens showed insignificant changes in FXR1 expression across therapy. As expected, alveolar histology, translocation presence, stage, and clinical group associated with worse survival.

CONCLUSIONS

FXR1 was expressed strongly across RMS specimens at diagnosis regardless of disease or patient characteristics, and particularly in undifferentiated cells. Reduction in FXR1 expression after chemotherapy associated with improved survival for embryonal and translocation-negative RMS patients.

Extraosseous Ewing's Sarcoma: Pictorial Review of Imaging Findings, Differential Diagnosis, and Pathologic Correlation

Extraosseous Ewing's sarcoma (EES), first described in 1969, is a malignant mesenchymal tumor just like its intraosseous counterpart. Although Ewing's sarcomas are common bone tumors in young children, EESs are rarer and more commonly found in older children/adults, often carrying a poorer prognosis. We discuss the multimodality imaging features of EES and the differential diagnosis of an aggressive appearing mass in proximity to skeletal structures, with pathologic correlates. This review highlights the need to recognize the variability of radiologic findings in EES such as the presence of hemorrhage, rich vascularity, and cystic or necrotic regions and its imaging similarity to other neoplasms that are closely related pathologically.

Case Report: Paratesticular Rhabdomyosarcoma

Paratesticular rhabdomyosarcoma (RMS) accounts for only 7% of all the RMS cases. Due to the limited available data, there is no consensus on the diagnosis and management of the paratesticular tumors. Here, we interrogated two paratesticular RMS cases in 25 and 27-year-old men presenting with painless and rapidly growing mass in the scrotum. Whereas the data showed no upregulation of tumor markers such as β-human chorionic gonadotropin (β-HCG), alpha-fetoprotein (AFP), and lactate dehydrogenase (LDH), scrotal ultrasonography and magnetic resonance imaging indicated the existence of paratesticular and inguinal lesions respectively. There was local recurrence in one patient who underwent radical orchiectomy for the sarcoma one year ago. In addition, the CT scans showed no occurrence of distant metastasis. The two patients underwent radical inguinal orchiectomy or resection of the recurrent tumors with nerve-sparing retroperitoneal lymph node dissection. Histologic examination revealed embryonal RMS (eRMS) without lymph node metastasis. We highlight the importance of multi-disciplinary participation for paratesticular RMS detection and preoperative ultrasound-guided needle biopsy (UNB) for rapid confirmatory diagnosis. Complete surgical resection coupled with chemotherapy and radiotherapy is the main treatment option for the paratesticular RMS. In addition, sperm cryopreservation treatment and endocrine follow-up could increase the overall survival and quality of life of the patients.

Evaluation of Myogenin and MyoD1 as Immunohistochemical Markers of Canine Rhabdomyosarcoma

Canine rhabdomyosarcoma (RMS) presents a diagnostic challenge due to its overlapping histologic features with other soft tissue sarcomas. The diagnosis of RMS currently relies on positive immunohistochemical (IHC) labeling for desmin; however, desmin expression is also observed in non-RMS tumors. Myogenin and MyoD1 are transcription factors reported to be sensitive and specific IHC markers for human RMS, but they are not widely used in veterinary oncology. The goals of this study were to develop an IHC protocol for myogenin and MyoD1, evaluate myogenin and MyoD1 labeling in canine RMS, and report clinical outcomes. Sixteen cases of possible RMS were retrospectively evaluated. A diagnosis of RMS was confirmed in 13 cases based on histological features and immunolabeling for myogenin and MyoD1, with the aid of electron microscopy in 2 cases. Desmin was negative in 3 cases of RMS. Two cases were of the sclerosing variant. The median age of dogs with RMS was 7.2 years. Anatomic tumor locations included previously reported sites such as bladder, larynx, heart, and orbit, as well as other locations typical of soft tissue sarcomas. Survival ranged from 47 to 1480 days for 5 dogs with available data. This study demonstrated that MyoD1 and myogenin should be included with desmin as part of a diagnostic IHC panel for canine RMS. Utilization of these antibodies to improve the accuracy of canine RMS diagnosis will ultimately allow for better characterization of the biological behavior and clinical outcomes of this disease, providing the groundwork for future comparative investigations in canine RMS.

Rhabdomyosarcoma: From Obscurity to Clarity in Diagnosis … But With Ongoing Challenges in Management: The Farber-Landing Lecture of 2020

Rhabdomyosarcoma, the most common soft tissue sarcoma in childhood, has challenged and intrigued soft tissue pathologists ever since the original descriptions. Once based on the identification of rhabdomyoblastic cells with elongate eosinophilic cytoplasm, the diagnosis has evolved to include tumors composed only of primitive mesenchymal cells but now relies heavily on immunohistochemical stains for desmin, myogenin, and MyoD. Rhabdomyosarcomas show a variety of histological patterns, giving rise to classifications that have included embryonal, alveolar, botryoid, pleomorphic, spindle cell, and sclerosing subtypes. These have been linked to prognosis and treatment assignment in the past, but that concept has been superseded by the identification of PAX3-FOXO1 or PAX7-FOXO1 fusions. Fusion testing results are more predictive of outcome and have become standard practice in clinical management. However, high risk tumors with alveolar histology or metastatic disease continue to resist oncologic treatment.

Alveolar rhabdomyosarcoma with regional nodal involvement: Results of a combined analysis from two cooperative groups

BACKGROUND

Treatment of children and adolescents with alveolar rhabdomyosarcoma (ARMS) and regional nodal involvement (N1) have been approached differently by North American and European cooperative groups. In order to define a better therapeutic strategy, we analyzed two studies conducted between 2005 and 2016 by the European paediatric Soft tissue sarcoma Study Group (EpSSG) and Children's Oncology Group (COG).

METHODS

We retrospectively identified patients with ARMS N1 enrolled in either EpSSG RMS2005 or in COG ARST0531. Chemotherapy in RMS2005 comprised ifosfamide + vincristine + dactinomycin + doxorubicin (IVADo), IVA and maintenance (vinorelbine, cyclophosphamide); in ARST0531, it consisted of either vincristine + dactinomycin + cyclophosphamide (VAC) or VAC alternating with vincristine + irinotecan (VI). Local treatment was similar in both protocols.

RESULTS

The analysis of the clinical characteristics of 239 patients showed some differences between study groups: in RMS2005, advanced Intergroup Rhabdomyosarcoma Study Group (IRS) and large tumors predominated. There were no differences in outcomes between the two groups: 5-year event-free survival (EFS), 49% (95% confidence interval [CI]: 39-59) and 44% (95% CI: 30-58), and overall survival (OS), 51% (95% CI: 41-61) and 53.6% (95% CI: 40-68) in RMS2005 and ARST0531, respectively. In RMS2005, EFS of patients with FOXO1-positive tumors was significantly inferior to those with FOXO1-negative (49.3% vs 73%, P = .034). In contrast, in ARST0531, EFS of patients with FOXO1-positive tumors was 45% compared with 43.8% for those with FOXO1-negative.

CONCLUSIONS

The outcome of patients with ARMS N1 was similar in both protocols. However, patients with FOXO1 fusion-negative tumors enrolled in RMS2005 showed a significantly better outcome, suggesting that different strategies of chemotherapy may have an impact in the outcome of this subgroup of patients.

Pathology of childhood rhabdomyosarcoma: A consensus opinion document from the Children's Oncology Group, European Paediatric Soft Tissue Sarcoma Study Group, and the Cooperative Weichteilsarkom Studiengruppe

The diagnosis and classification of rhabdomyosarcoma (RMS) has undergone several shifts over the last 30 years. While the main diagnostic categories remained the same, changes in the histologic criteria necessary for diagnosis, as well as varied reliance on immunohistochemical and molecular data over time, have created confusion, particularly regarding how these shifts impacted risk stratification and enrollment onto clinical trials. The goal of this report is to review the evolution and current status of RMS diagnosis, focusing on diagnostic criteria in the Children's Oncology Group (COG), the European Paediatric Soft Tissue Sarcoma Group (EpSSG), and the Cooperative Weichteilsarkom Studiengruppe (CWS). In addition, we emphasize research tools used to classify RMS and address biological questions within current clinical trials run by each group. The INternational Soft Tissue SaRcoma ConsorTium (INSTRuCT) initiative will maximize potential to optimize risk stratification by recognizing and accounting for differences in historical data and current practices.

Embryonal rhabdomyosarcoma of external ear - A rare case report

The Rationale:

Rhabdomyosarcoma (RMS) is an uncommon tumour which presents at a wide variety of different head and neck sites. They are highly aggressive malignant mesenchymatous soft tissue sarcomas. Their occurrence in the outer ear is extremely rare.

Patient Concerns:

A 17-year-old female patient reported with a chief complaint of steady increase in growth over the left ear since 6 months, which is not associated with pain and ulceration.

Diagnosis:

Edge biopsy sections of the swelling over the left pinna and immunohistochemistry records of cells show MYODI positive confirming as Embryonal RMS.

Treatment:

Left auriculectomy and supra-omohyoid neck dissection with level V lymph node was performed.

Outcomes:

Uneventful postoperative healing in the resected site was elicited in the follow-up period of 1 year with no recurrence.

Take-away Lessons:

External ear RMS is extremely rare. Careful clinical, radiological and histopathological evaluation are essential for prompt definitive diagnosis and for successful management.

Germline Cancer Predisposition Variants in Pediatric Rhabdomyosarcoma: A Report From the Children's Oncology Group

BACKGROUND

Several cancer-susceptibility syndromes are reported to underlie pediatric rhabdomyosarcoma (RMS); however, to our knowledge there have been no systematic efforts to characterize the heterogeneous genetic etiologies of this often-fatal malignancy.

METHODS

We performed exome-sequencing on germline DNA from 615 patients with newly diagnosed RMS consented through the Children's Oncology Group. We compared the prevalence of cancer predisposition variants in 63 autosomal-dominant cancer predisposition genes in these patients with population controls (n = 9963). All statistical tests were 2-sided.

RESULTS

We identified germline cancer predisposition variants in 45 RMS patients (7.3%; all FOXO1 fusion negative) across 15 autosomal dominant genes, which was statistically significantly enriched compared with controls (1.4%, P = 1.3 × 10-22). Specifically, 73.3% of the predisposition variants were found in predisposition syndrome genes previously associated with pediatric RMS risk, such as Li-Fraumeni syndrome (TP53) and neurofibromatosis type I (NF1). Notably, 5 patients had well-described oncogenic missense variants in HRAS (p.G12V and p.G12S) associated with Costello syndrome. Also, genetic etiology differed with histology, as germline variants were more frequent in embryonal vs alveolar RMS patients (10.0% vs 3.0%, P = .02). Although patients with a cancer predisposition variant tended to be younger at diagnosis (P = 9.9 × 10-4), 40.0% of germline variants were identified in those older than 3 years of age, which is in contrast to current genetic testing recommendations based on early age at diagnosis.

CONCLUSIONS

These findings demonstrate that genetic risk of RMS results from germline predisposition variants associated with a wide spectrum of cancer susceptibility syndromes. Germline genetic testing for children with RMS should be informed by RMS subtypes and not be limited to only young patients.

Testicular Torsion in a Rare Case of Prostatic Spindle Cell Rhabdomyosarcoma

Spindle cell sarcoma of the prostate is a rare variant of rhabdomyosarcoma (RMS), with the clinical experience limited to a handful of cases in the literature. We report a rare case of spindle cell rhabdomyosarcoma (SC-RMS) who presented to us with testicular torsion features. A 20-year-old male presented initially with lower urinary tract symptoms and features of epidiymo-orchitis, which was managed conservatively. He later presented with features suggestive of testicular torsion and underwent orchidopexy. The patient developed postoperative urinary retention. On per-rectal examination, there was gross prostatomegaly. He was evaluated with a trans-rectal biopsy and contrast-enhanced computed tomography (CECT). Subsequently, he was found to have metastatic prostatic SC-RMS, which is a rare disease. He was started on chemotherapy and radiotherapy. SC-RMS is a variant that has a comparatively favorable prognosis in children and an aggressive course in adults, as reported in the few cases so far. The treatment regimen is still evolving, and there is no consensus on the therapeutic approach. All these factors together result in the dismal outlook of patients diagnosed with this condition.

Survival outcomes of patients with localized FOXO1 fusion-positive rhabdomyosarcoma treated on recent clinical trials: A report from the Soft Tissue Sarcoma Committee of the Children's Oncology Group

BACKGROUND

The objective of this analysis was to evaluate the clinical factors influencing survival outcomes in patients with localized (clinical group I-III), FOXO1 fusion-positive rhabdomyosarcoma (RMS).

METHODS

Patients with confirmed FOXO1 fusion-positive RMS who were enrolled on 3 completed clinical trials for localized RMS were included in the analytic cohort. Outcomes were analyzed using the Kaplan-Meier method to estimate event-free survival (EFS) and overall survival (OS), and the curves were compared using the log-rank test. A Cox proportional hazards regression model was used to perform multivariate analysis of prognostic factors that were significant in the univariate analysis.

RESULTS

The estimated 4-year EFS and OS of 269 patients with localized, FOXO1 fusion-positive RMS was 53% (95% CI, 47%-59%) and 69% (95% CI, 63%-74%), respectively. Univariate analysis revealed that several known favorable clinical characteristics, including age at diagnosis between 1 and 9 years, complete surgical resection, tumor size ≤5 cm, favorable tumor site, absence of lymph node involvement, confinement to the anatomic site of origin, and PAX7-FOXO1 fusion, were associated with improved outcomes. Multivariate analysis identified older age (≥10 years) and large tumor size (>5 cm) as independent, adverse prognostic factors for EFS within this population, and patients who had both adverse features experienced substantially inferior outcomes.

CONCLUSIONS

Patients with localized, FOXO1 fusion-positive RMS can be further risk stratified based on clinical features at diagnosis, and older patients with large primary tumors have the poorest prognosis.

Germline predisposition to genitourinary rhabdomyosarcoma

Multiple genetic conditions predispose to the development of rhabdomyosarcoma. Much of the literature on rhabdomyosarcoma in genetic syndromes does not sub-divide the location or the pathology of the sarcomas. Therefore, there are limited data on genitourinary specific associations with certain genetic syndromes. We summarize, here, the primary differential considerations for rhabdomyosarcoma of the genitourinary system. Primary considerations include DICER1 pathogenic variation, Li-Fraumeni syndrome, constitutional mismatch repair deficiency, mosaic variegated aneuploidy, neurofibromatosis type 1, Noonan syndrome, other RASopathies, Costello syndrome, and Beckwith-Wiedemann syndrome. Some conditions may present with specific pathological, clinical and/or family history features, but for others, the genitourinary tumor may be the only presenting sign at the time of diagnosis. Genetic evaluation with counseling and/or testing may help identify an underlying tumor predisposition. This manuscript serves as an introduction to germline considerations for children with genitourinary rhabdomyosarcoma.

Score for the Survival Probability of Patients With Orbital Rhabdomyosarcoma After Surgery: A Long-Term and Large Cohort Study

Orbital rhabdomyosarcoma (RMS) is a relatively rare primary malignancy occurring in children. The objective of this study was to evaluate the cumulative incidence of cancer-specific death and competing risk of death among RMS patients after surgery and to build nomograms to predict overall survival (OS) and cancer-specific survival (CSS) based on a large population-based cohort. The records of 217 patients who were pathologically diagnosed with an orbital RMS between 1973 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database were retrospectively analyzed. The 10-, 20-, and 40-years OS rates and cancer-specific mortality were 82.5, 72.2, and 48.9%, respectively, and 14.8, 21.7, and 21.7%, respectively. The established nomograms were well-calibrated and validated, with a concordance index (C-index) of 0.901 and 0.944 for OS prediction, 0.923 and 0.904, for CSS prediction in the training and validation cohorts, respectively. The values of area under the receiver operating characteristic curve (AUC) for 10-, 20-, and 40-years OS and CSS prediction were 0.908, 0.826, and 0.847, and 0.924, 0.863, and 0.863, respectively. The established nomogram showed relatively good performances and could be convenient individualized predictive tools for prognostic prediction in RMS patients.

Adult laryngeal Embryonal Rhabdomyosarcoma: a case report and literature review

Background

Laryngeal rhabdomyosarcomas (RMSs) mainly occurred in children, while were extremely rare in adults. Consequently, less information was available to guide clinicians to manage adult RMSs in larynx.

Case presentation

A 42-year-old man presented with a 2-year history of gradually worsening hoarseness. Then, he underwent a surgery with suspension laryngoscope with initially being diagnosed as vocal cord cyst. Unexpectedly, the lesion was proved to be embryonal rhabdomyosarcoma (ERMS), pathologically. Next, he underwent chemoradiotherapy, while the tumor relapsed 18 months after the last treatment. Subsequently, a vertical hemilaryngectomy and a right selective neck dissection was performed, and the chemotherapy according to the anticancer drug sensitivity in vitro was arranged. Until the last check-up 18 months after chemotherapy, the patient did not display clinical or radiological signs of local recurrence and metastases.

Conclusions

Misdiagnosis and missed diagnosis of laryngeal RMSs might appear when tumors presented as smooth protuberance. We reported the first case of laryngeal RMSs in an adult with the multidisciplinary strategy based on the chemosensitivity assay in vitro. Furthermore, a systematic review of the literature was also discussed, highlighting the initial diagnostic pitfalls and subsequent management problems that may occur with this uncommon tumor.

Rhabdomyosarcoma from uterus to heart

Rhabdomyosarcoma (RMS) is a malignant soft tissue tumor of the pediatric population which is  rarely seen in adults. Metastatic rhabdomyosarcoma is even rarer. We present an unusual case of a 49 year old female presenting with palpitations and uterine bleeding. An Echo-cardiogram revealed a large oval mass on the posterior mitral leaflet and a Computerized Tomography (CT) scan of the abdomen revealed a uterine growth. Surgical excision of the cardiac mass was done and histological analysis of cardiac lesion confirmed it to be rhabdomyosarcoma with a primary source in the uterus. The patient became asymptomatic from a cardiac standpoint after excision of the mass and was scheduled for chemo/radiation therapy for the primary uterine malignancy. Metastatic cardiac rhabdomyosarcoma can be confused with a myxoma or any other primary or secondary cardiac tumors resulting in delayed diagnosis. However, its aggressive nature makes it a life-threatening tumor that requires an early diagnosis to prevent fatal consequences.

Primary rhabdomyosarcoma of tunica vaginalis misdiagnosing as hydrocele: A case report and literature review

Primary rhabdomyosarcoma of tunica vaginalis is very rare. We report a case of a 15-year-old man presenting as hydrocele. Pre-operatively, no masses were detected by ultrasonography. Hydrocelectomy was performed. At surgery, a 0.8 cm polypoid nodule and diffusely thickened tunica were found. Pathologic examination finally revealed rhabdomyosarcoma. A PET-CT was then performed and indicated scrotal implantation metastasis. The patient underwent radical inguinal orchiectomy and was treated with chemotherapy and radiotherapy after surgery. At 12 months of follow-up, he remained disease-free.

Primary Conjunctival Rhabdomyosarcoma in a Pediatric Patient

Rhabdomyosarcomas are neoplasms with a high degree of malignancy and arise from the embryonic mesenchyme. They represent approximately 5% of all pediatric tumors and their main locations are the head and neck (45%), trunk (40%), and extremities (15%). Twenty-five percent to 30% of the head and neck rhabdomyosarcomas appear in the orbit; however, its origin from the conjunctiva is rare, with few case reports published in the literature.

We present the case of a five-year-old girl with a diagnosis of primary embryonic rhabdomyosarcoma of the conjunctiva, treated with surgery and chemotherapy. After completing the treatment, it was followed up with controls for oncological ophthalmology, pediatric hematology-oncology, and radiotherapy oncology every six months with magnetic resonance of the orbits. Two years after the end of treatment, the patient is disease-free.

Conjunctiva rhabdomyosarcoma is a rare lesion, with few previously reported cases. In the reported case, the histopathological findings and positivity of the different immunohistochemical markers allowed a definitive diagnosis of rhabdomyosarcoma. The excellent prognosis of this pathology is probably linked to the early diagnosis of the disease and the timely administration of radical treatment.

It is essential to be able to identify conjunctival rhabdomyosarcoma from its clinical and histopathological characteristics in order to achieve early diagnosis and provide adequate treatment to patients.

Primary cardiac rhabdomyosarcoma successfully treated with eribulin: a case report

Rhabdomyosarcoma is the most common soft tissue sarcoma that typically occurs in children and adolescents and is rare in adults. Furthermore, as cardiac tumor is rare, adult cardiac rhabdomyosarcoma is a very rare entity. Here, we report the case of a 68-year-old woman with cardiac rhabdomyosarcoma who was successfully treated with eribulin. She presented with sudden loss of consciousness, which was attributed to the cardiac tumor. The tumor was resected by emergency surgery and was diagnosed as embryonal rhabdomyosarcoma. Although surgical treatment alleviated her symptoms, the residual tumor increased in size after surgery and required multimodal treatment. First-line chemotherapy with the vincristine, actinomycin D, and cyclophosphamide regimen had to be discontinued owing to adverse events, and thus eribulin was used as a second-line treatment. Eribulin was better tolerated and helped maintain a stable disease status for >18 months. This reported case of cardiac rhabdomyosarcoma is the first case to be successfully treated with eribulin over a relatively long period. Eribulin therapy may thus be a viable treatment alternative for rhabdomyosarcoma.

Downregulation of POFUT1 Impairs Secondary Myogenic Fusion Through a Reduced NFATc2/IL-4 Signaling Pathway

Past work has shown that the protein O-fucosyltransferase 1 (POFUT1) is involved in mammal myogenic differentiation program. Pofut1 knockdown (Po –) in murine C2C12 cells leads to numerous elongated and thin myotubes, suggesting significant defects in secondary fusion. Among the few pathways involved in this process, NFATc2/IL-4 is described as the major one. To unravel the impact of POFUT1 on secondary fusion, we used wild-type (WT) C2C12 and Po – cell lines to follow Myf6, Nfatc2, Il-4 and Il-4rα expressions during a 120 h myogenic differentiation time course. Secreted IL-4 was quantified by ELISA. IL-4Rα expression and its labeling on myogenic cell types were investigated by Western blot and immunofluorescence, respectively. Phenotypic observations of cells treated with IL-4Rα blocking antibody were performed. In Po –, we found a decrease in nuclei number per myotube and a downexpression of Myf6. The observed downregulation of Nfatc2 is correlated to a diminution of secreted IL-4 and to the low level of IL-4Rα for reserve cells. Neutralization of IL-4Rα on WT C2C12 promotes myonuclear accretion defects, similarly to those identified in Po –. Thus, POFUT1 could be a new controller of myotube growth during myogenesis, especially through NFATc2/IL-4 signaling pathway.

Undifferentiated sarcoma of the soft tissues with cystic degeneration: Case report and review of literature

Undifferentiated sarcoma (UNDS) of the soft tissue is an exceedingly rare disease. Its diagnosis depends mainly on molecular and immunohistochemical analyses to exclude other soft-tissue sarcomas. It is difficult to confirm a positive diagnosis by imaging pathological features because of their rarity and similarity with other conditions. Since 2013, only 13 cases of undifferentiated soft-tissue sarcoma, mostly diagnosed through imaging of solid tumors in infant and children, have been reported. The authors present a rare case of a 3-month-old Chinese boy with UNDS primarily in the left lower extremity and characterized by a cystic and solid growth pattern.

Preclinical rationale for entinostat in embryonal rhabdomyosarcoma

BACKGROUND

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the pediatric cancer population. Survival among metastatic RMS patients has remained dismal yet unimproved for years. We previously identified the class I-specific histone deacetylase inhibitor, entinostat (ENT), as a pharmacological agent that transcriptionally suppresses the PAX3:FOXO1 tumor-initiating fusion gene found in alveolar rhabdomyosarcoma (aRMS), and we further investigated the mechanism by which ENT suppresses PAX3:FOXO1 oncogene and demonstrated the preclinical efficacy of ENT in RMS orthotopic allograft and patient-derived xenograft (PDX) models. In this study, we investigated whether ENT also has antitumor activity in fusion-negative eRMS orthotopic allografts and PDX models either as a single agent or in combination with vincristine (VCR).

METHODS

We tested the efficacy of ENT and VCR as single agents and in combination in orthotopic allograft and PDX mouse models of eRMS. We then performed CRISPR screening to identify which HDAC among the class I HDACs is responsible for tumor growth inhibition in eRMS. To analyze whether ENT treatment as a single agent or in combination with VCR induces myogenic differentiation, we performed hematoxylin and eosin (H&E) staining in tumors.

RESULTS

ENT in combination with the chemotherapy VCR has synergistic antitumor activity in a subset of fusion-negative eRMS in orthotopic "allografts," although PDX mouse models were too hypersensitive to the VCR dose used to detect synergy. Mechanistic studies involving CRISPR suggest that HDAC3 inhibition is the primary mechanism of cell-autonomous cytoreduction in eRMS. Following cytoreduction in vivo, residual tumor cells in the allograft models treated with chemotherapy undergo a dramatic, entinostat-induced (70-100%) conversion to non-proliferative rhabdomyoblasts.

CONCLUSION

Our results suggest that the targeting class I HDACs may provide a therapeutic benefit for selected patients with eRMS. ENT's preclinical in vivo efficacy makes ENT a rational drug candidate in a phase II clinical trial for eRMS.

Genetic profiling of rhabdomyosarcoma with clinicopathological and radiological correlation

OBJECTIVE

Orbital Rhabdomyosarcoma is a highly malignant tumor predominantly affecting children. Our study adds more understanding of this tumor to ophthalmologists from the clinicopathological, radiological and genetic aspects.

DESIGN

A retrospective clinicopathological and radiological study of ocular rhabdomyosarcoma with genetic profiling.

PARTICIPANTS

All the cases with confirmed tissue diagnosis of orbital rhabdomyosarcoma presenting at a tertiary eye hospital in Riyadh, Saudi Arabia during the period 1985-2015.

METHODS

Charts and histological slides of 26 patients were reviewed. DNA was extracted from paraffin-embedded biopsies and genotyping was performed to detect chromosomal abnormalities and Copy-number variations regions.

RESULTS

18 males and 8 females were included with a mean age at presentation of 6.9 years (SD of 4.4). Proptosis and globe displacement were the commonest clinical presentations. Embryonal histopathological type was the commonest (73.1%) with superior orbital involvement (p = 0.024). Using magnetic resonance imaging, the embryonal type showed higher Apparent diffusion coefficient (ADC) value compared to the alveolar type (p = 0.98). Genetic profiling showed Copy-number gain in regions spanning PAX3, DDIT3, Gli, Wnt6 genes. DICER1 gene implication was found in 9 sporadic cases.

CONCLUSION

Rhabdomyosarcoma is rare and occurs with a mean age of 7 years, predominantly among males. The commonest embryonal type is significantly correlated with superior orbital involvement. Radiologically, it shows an ADC of 0.67-0.09 × 10^-3mm²/s. (p = 0.98). The gain in PAX3, DDIT3, Gli1, Wnt6 genes is a new finding while the DICER1 gene implication in the absence of familial hereditary carcinoma is another interesting finding.

Pioneer in Pediatric Pathology: William A (Bill) Newton Jr (1923-)

William A (Bill) Newton Jr practiced pediatric pathology and hematology/oncology at Children's Hospital of Columbus, Ohio, for over 40 years starting in 1952. Newton was an original member of the Pediatric Pathology Club, which preceded the Society for Pediatric Pathology, and was its president from 1968 to 1969. He published important independent observations in pediatric pathology, helped establish systematic cooperative pediatric tumor pathology review by experts, became an acclaimed expert on the diagnosis of rhabdomyosarcoma, was a critical contributor to many pediatric oncology clinical trials, made important early contributions to tumor banking in pediatrics, and trained numerous pediatric pathology and pediatric oncology fellows. Finally, he concluded his career as a humanitarian, leading important volunteer work aimed at improving pediatric cancer care in China. This most interesting pediatric pathologist was simultaneously a Brigadier General in the U.S. Army. Bill Newton's life and career, which is reviewed in detail here, should be of immense interest and an inspiration to the Pediatric & Developmental Pathology readership.

Update on Myogenic Sarcomas

Myogenic sarcomas include soft tissue sarcomas that show skeletal muscle differentiation (rhabdomyosarcoma) and those with smooth muscle differentiation (leiomyosarcoma). Rhabdomyosarcomas are more common in the pediatric age group and leiomyosarcomas occur more often in the adult population. Based on the clinico-pathologic features and genetic abnormalities identified, the rhabdomyosarcomas are classified into embryonal, alveolar, spindle cell/sclerosing, and pleomorphic subtypes. Each subtype shows distinctive morphology and has characteristic genetic abnormalities. In this update on myogenic sarcomas, each entity is discussed with special emphasis on recent updates in genetic findings and the diagnostic approach to these tumors.

Demographic and Treatment Variables Influencing Outcome for Localized Paratesticular Rhabdomyosarcoma: Results From a Pooled Analysis of North American and European Cooperative Groups

PURPOSE

Treatment recommendations for localized paratesticular rhabdomyosarcoma (PT RMS) differ in North America and Europe. We conducted a pooled analysis to identify demographic features and treatment choices that affect outcome.

PATIENTS AND METHODS

We retrospectively analyzed the effect of nine demographic variables and four treatment choices on event-free survival (EFS) and overall survival (OS) from 12 studies conducted by five cooperative groups.

RESULTS

Eight hundred forty-two patients with localized PT RMS who enrolled from 1988 to 2013 were included. Patients age ≥ 10 years were more likely than younger patients to have tumors that were > 5 cm, enlarged nodes (N1), or pathologically involved nodes ( P ≤ .05 each). With a median follow-up of 7.5 years, Kaplan-Meier estimates for 5-year EFS and OS were 87.7% and 94.8%, respectively. Of demographic variables, cooperative group, era of enrollment, age category, tumor size, Intergroup Rhabdomyosarcoma Study group, and T stage affected EFS ( P ≤ .05 each). Surgical assessment of regional nodes, which was performed in 23.5% of patients-usually in those age ≥ 10 years or with suspicious or N1 nodes-was the only treatment variable associated with EFS by univariable and multivariable analyses ( P ≤ .05 each) in patients age ≥ 1 year. A variable selection procedure on a proportional hazards regression model selected era of enrollment, age, tumor size, and surgical assessment of regional nodes as significant ( P ≤ .05 each) in the EFS model, and era of enrollment, age, tumor size, and histology ( P ≤ .05 each) in the OS model.

CONCLUSION

Localized PT RMS has a favorable prognosis. Age ≥ 10 years at diagnosis and tumor size larger than 5 cm are unfavorable prognostic features. Surgical assessment of regional nodes is important in patients age ≥ 10 years and in those with N1 nodes as it affects EFS.

The addition of cixutumumab or temozolomide to intensive multiagent chemotherapy is feasible but does not improve outcome for patients with metastatic rhabdomyosarcoma: A report from the Children's Oncology Group

BACKGROUND

The outcome for patients with metastatic rhabdomyosarcoma (RMS) remains poor. A previous Children's Oncology Group (COG) study (ARST0431) for patients with metastatic RMS produced no improvement in outcome using multiple cytotoxic agents in a dose-intensive manner. The authors report results from the subsequent COG study (ARST08P1), which evaluated the feasibility and efficacy of adding cixutumumab (insulin-like growth factor-1 monoclonal antibody) or temozolomide to the ARST0431 intensive chemotherapy backbone.

METHODS

Two nonrandomized pilot studies were conducted in patients with metastatic RMS, initially to determine feasibility, and both pilots were expanded to assess efficacy. All patients received 54 weeks of chemotherapy, including vincristine/irinotecan, interval-compressed vincristine/doxorubicin/cyclophosphamide alternating with ifosfamide/etoposide, and vincristine/dactinomycin/cyclophosphamide. In pilot 1, patients received intravenous cixutumumab (3, 6, or 9 mg/kg) once weekly throughout therapy. In pilot 2, patients received oral temozolomide (100 mg/m² ) daily for 5 days with irinotecan. All patients received radiation to the primary tumor and to metastatic sites.

RESULTS

One hundred sixty-eight eligible patients were enrolled (97 on pilot 1 and 71 on pilot 2). Most patients were aged ≥10 years (73%), with alveolar histology (70%), and had bone and/or bone marrow metastases (59%). Toxicities observed in each pilot were similar to those reported on ARST0431. With a median follow-up of 2.9 years, the 3-year event-free survival rate was 16% (95% confidence interval, 7%-25%) with cixutumumab and 18% (95% confidence interval, 2%-35%) with temozolomide.

CONCLUSIONS

The addition of cixutumumab or temozolomide to intensive multiagent chemotherapy for metastatic RMS was safe and feasible. Neither agent improved outcome compared with the same chemotherapy that was used on ARST0431.

Rabdomyosarcoma of the Mandible: An Uncommon Clinical Presentation

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and adolescents. Most patients present with a mass in the head and neck region, urogenital region, or with distal extremity involvement. The authors describe a challenging case of a 6-year-old male patient presenting with mandibular RMS. The clinical/radiographic/tomographic evaluations classified the tumor as an advanced stage (stage IV), with a mass of 6.0 cm involving the left side of the mandible and parotid region. The biopsy revealed round, spindled, and pleomorphic cells with hyperchromatic nuclei and rare larger rhabdomyoblasts with eosinophilic cytoplasm. The diagnosis was of embryonal RMS. The patient was referred for treatment with cycles of chemotherapy; however, pulmonary and bone marrow metastasis were identified. Radiotherapy and local surgery with microvascular reconstruction were performed later; however, the patient died after a few months. Early diagnosis is critical for a good prognosis and cure of patients with RMS. Correct diagnosis considering also the histological subtype is important for adequate treatment, which according to the literature is not uniform probably because of the rarity of this neoplasm.