Adult-type rhabdomyosarcoma: analysis of 57 cases with clinicopathologic description, identification of 3 morphologic patterns and prognosis

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.

Rhabdomyosarcoma: Updates on classification and the necessity of molecular testing beyond immunohistochemistry

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and adolescents under the age of 20. The current World Health Organization (WHO) classification for soft tissue and bone tumors recognizes 4 distinct subtypes of RMS based on clinicopathological and molecular genetic features: embryonal, alveolar, spindle cell/sclerosing and pleomorphic subtypes. However, with the increased use of molecular techniques, the classification of rhabdomyosarcoma has been evolving rapidly. New subtypes such as osseus RMS harboring TFCP2/NCOA2 fusions or RMS arising in inflammatory rhabdomyoblastic tumor have been emerging within the last decade, adding to the complexity of diagnosing skeletal muscle tumors. This review article provides an overview of classically recognized distinctive subtypes as well as new, evolving subtypes and discusses important morphologic, immunophenotypic and molecular genetic features of each subtype including recommendations for a diagnostic approach of malignant skeletal muscle neoplasms.

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.

Multifaceted Spindle Cell/Sclerosing Rhabdomyosarcoma With Role of Immunohistochemistry in Avoiding Misdiagnosis: A Multi-Institutional Study of 45 Distinct Tumors

Background. Spindle cell/sclerosing rhabdomyosarcoma is a rare neoplasm and has an aggressive clinical course. Because of its rarity, we performed a multi-institutional collaboration to comprehend the overarching clinical, histopathological, and immunohistochemical characteristics of a cohort of spindle cell/sclerosing rhabdomyosarcoma. Materials and Methods. Forty-five patients with spindle cell/sclerosing rhabdomyosarcoma were identified. Demographics, clinical, histopathological, and immunohistochemistry data were reviewed and recorded. Results. The patients' age ranged from 1 to 85 years with a male to female ratio of 1.2:1. There were 15 children/adolescents and 30 adults. Eighteen (40%) tumors were located in the head and neck region. Twenty-four (53%) tumors displayed a bimorphic cellular arrangement with hypercellular areas having short, long, and sweeping fascicular and herringbone pattern, and hypocellular areas with stromal sclerosis and associated hyalinized and/or chondromyxoid matrix. Histomorphological differentials considered were leiomyosarcoma, malignant peripheral nerve sheath tumor, fibrosarcoma, nodular fasciitis, liposarcoma, synovial sarcoma, sarcomatoid carcinoma, solitary fibrous tumor, dermatofibrosarcoma protuberans, and schwannoma. Six tumors exhibited marked stromal sclerosis. The myogenic nature was confirmed by immunohistochemistry. Positivity for at least one skeletal muscle-associated marker (MyoD1 and/or myogenin) was observed. Conclusion. Spindle cell/sclerosing rhabdomyosarcoma diagnosis can be challenging as a number of malignant spindle cell neoplasm mimic this entity. Thus a correct diagnosis requires immunohistochemical work up with a broad panel of antibodies. In view of rarity of this neoplasm, further studies on a large cohort of patients with clinical follow-up data are needed for a better understanding of this tumor.

Unraveling the Clinicopathological Diversity and Subtypes of Rhabdomyosarcoma: A Study From a Tertiary Care Center

Background and objective Rhabdomyosarcoma (RMS) is a rare and malignant mesenchymal tumor characterized by skeletal muscle differentiation. While it is a common soft tissue sarcoma in children, its incidence significantly decreases with advancing age, rendering it exceptionally rare in individuals aged more than 45 years. This study aimed to shed light on the clinicopathological diversity and subtypes of RMS, thereby providing a comprehensive overview for enabling diagnostic precision and therapeutic strategies in treating this infrequently encountered malignancy in adults. Methodology This was a hospital-based cross-sectional study conducted in the Department of Pathology. Patients who were diagnosed with RMS over a period of three years were included in the study. The demographic features such as age and sex and aspects related to the tumor site, size, subtypes of RMS, and immunohistochemical expression were studied. Results A total of 14 cases were included in our study. The age at diagnosis ranged from four months to 65 years with a male-to-female ratio of 1:2.5. The sites of presentation were head and neck, trunk, pelvis, genitourinary tract, and retroperitoneum. The histological types were embryonal, alveolar, pleomorphic, and mixed and spindle cell types. The tumor cells were positive for immunohistochemistry markers desmin, MyoD1, and vimentin. Conclusion This study delved into the clinicopathological intricacies of RMS, offering comprehensive insights into its diverse subtypes. Our findings underscore the unique presentation of RMS in adults, with trunk and genitourinary tracts emerging as primary sites and alveolar and pleomorphic RMS observed as the predominant histological subtypes. Furthermore, the study sheds light on rare subtypes with distinct anatomical distributions.

Complete loss of TP53 and RB1 is associated with complex genome and low immune infiltrate in pleomorphic rhabdomyosarcoma

Rhabdomyosarcoma accounts for roughly 1% of adult sarcomas, with pleomorphic rhabdomyosarcoma (PRMS) as the most common subtype. Survival outcomes remain poor for patients with PRMS, and little is known about the molecular drivers of this disease. To better characterize PRMS, we performed a broad array of genomic and immunostaining analyses on 25 patient samples. In terms of gene expression and methylation, PRMS clustered more closely with other complex karyotype sarcomas than with pediatric alveolar and embryonal rhabdomyosarcoma. Immune infiltrate levels in PRMS were among the highest observed in multiple sarcoma types and contrasted with low levels in other rhabdomyosarcoma subtypes. Lower immune infiltrate was associated with complete loss of both TP53 and RB1. This comprehensive characterization of the genetic, epigenetic, and immune landscape of PRMS provides a roadmap for improved prognostications and therapeutic exploration.

Adult Laryngeal Pleomorphic Rhabdomyosarcoma: A Rare Entity

Rhabdomyosarcoma (RMS) is a rare and aggressive cancerous tumor that arises from embryonal mesenchymal cells with skeletal muscle differentiation, and it is exceedingly rare that occurs specifically in the larynx. To date, only 22 instances of laryngeal pleomorphic RMSs have been documented in adults. Consequently, there is limited information available to assist healthcare professionals in effectively handling RMS in the larynx of adult patients. Here, we present an uncommon occurrence involving a 45-year-old man who experienced progressive hoarseness and received a diagnosis of pleomorphic RMS affecting the larynx. Pleomorphic RMS had been pathologically diagnosed after a vertical hemilaryngectomy. Following the surgical intervention, the patient underwent chemotherapy and radiation therapy. As of now, there have been no indications of tumor recurrence.

Pan-keratin Immunostaining in Human Tumors: A Tissue Microarray Study of 15,940 Tumors

To evaluate the efficiency of pan-keratin immunostaining, tissue microarrays of 13,501 tumor samples from 121 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types were analyzed by immunohistochemistry. In normal tissues, strong pan-keratin immunostaining was seen in epithelial cells. Staining intensity was lower in hepatocytes, islets of Langerhans, and pneumocytes but markedly reduced in the adrenal cortex. Pan-keratin was positive in ≥98% of samples in 62 (83%) of 75 epithelial tumor entities, including almost all adenocarcinomas, squamous cell and urothelial carcinomas. Only 17 of 121 tumor entities (13%) had a pan-keratin positivity rate between 25% and 98%, including tumors with mixed differentiation, endocrine/neuroendocrine tumors, renal cell carcinomas, adrenocortical tumors, and particularly poorly differentiated carcinoma subtypes. The 15 entities with pan-keratin positivity in 0.9%-25% were mostly of mesenchymal origin. Reduced/absent pan-keratin immunostaining was associated with high UICC stage (p = 0.0001), high Thoenes grade (p = 0.0183), high Fuhrman grade (p = 0.0049), advanced tumor stage (p < 0.0001) and lymph node metastasis (p = 0.0114) in clear cell renal cell carcinoma, advanced pT stage (p = 0.0007) in papillary renal cell carcinoma, and with advanced stage (p = 0.0023), high grade (p = 0.0005) as well as loss of ER and PR expression (each p < 0.0001) in invasive breast carcinoma of no special type (NST). In summary, pan-keratin can consistently be detected in the vast majority of epithelial tumors, although pan-keratin can be negative a fraction of renal cell, adrenocortical and neuroendocrine neoplasms. The data also link reduced pan-keratin immunostaining to unfavorable tumor phenotype in in epithelial neoplasms.

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.

Alveolar rhabdomyosarcoma of epididymis: A case report

Rhabdomyosarcoma (RMS) is a soft tissue tumor, which is the most common in the head, neck, limbs, and trunk. RMS originating from the epididymis is extremely rare. Herein, we reported a 34-year-old patient with RMS on the right epididymis. For this case, right epididymal mass resection was performed and intraoperative freezing suggested a malignant tumor. Right testicular radical resection was subsequently adopted, with right epididymal alveolar RMS being pathologically diagnosed. Alternating VAC/VI chemotherapy was given after surgery, and tumor recurrence has not been found so far.

Pleomorphic Rhabdomyosarcoma: A Systematic Review with Outcome Analysis and Report of a Rare Abdominal Wall Lesion

Introduction. Pleomorphic rhabdomyosarcoma (RMS) is an aggressive and rare malignant neoplasm with a poor prognosis. As its name suggests, this tumor exhibits extensive pleomorphism with features of skeletal muscle differentiation. Due to its rarity, its diagnosis is often a clinical and pathological challenge. Since only small case series and a few scattered case reports exist in the literature, the impact of different demographic features, tumor site, and/or treatment modality on patient outcomes has yet to be extensively studied. Methods. We report a case of a pleomorphic RMS presenting atypically as an abdominal wall mass. We have also analyzed the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database to determine the factors affecting the outcome of this neoplasm. Moreover, we present a review and summary of pleomorphic RMS cases arising from the abdominal wall reported in the English language literature. Results. We found two hundred and forty-two cases of pleomorphic RMS in the SEER database. The majority of the patients were diagnosed after the age of 40, with the age of diagnosis showing a unimodal distribution. The majority of the patients were Caucasian (82%) and male (59%). Age of diagnosis, tumor stage, and surgical management significantly affected the patients' outcome, while patients' ethnicity, sex, or tumor site did not affect the outcome. We only found five previously reported cases of pleomorphic RMS arising from the abdominal wall. Conclusions. Pleomorphic RMS arising from the abdominal wall is extremely rare. Our data sheds light on the factors affecting the outcome of pleomorphic RMS. We have also discussed the challenges involving the histopathological diagnosis of this rare neoplasm and how to best approach this task.

Case Report: A PD-L1-Positive Patient With Pleomorphic Rhabdomyosarcoma Achieving an Impressive Response to Immunotherapy

There is currently a lack of effective systemic treatment for patients with advanced pleomorphic rhabdomyosarcoma (PRMS). Although programmed death protein 1 (PD-1) inhibitors have shown efficacy in various solid tumors, their effects on PRMS have not been well established. Here, we present a case of a 12-year-old Chinese male adolescent with metastatic PRMS who benefited from the PD-1 inhibitor nivolumab. The patient initially underwent primary tumor resection but failed to respond to subsequent first-line chemotherapy and second-line pazopanib treatment. Pathological examination showed positive PD-L1 expression and tumor-infiltrating lymphocytes in the tumor tissue, and the patient was administered nivolumab as a posterior-line treatment. After attaining a clinically partial response (PR), surgical resection was performed, which was followed by adjuvant nivolumab. At the time of the submission of this manuscript, the patient achieved recurrence-free survival (RFS) lasting 45 months and counting. This is the first clinical evidence that a patient with refractory PRMS was controlled by anti-PD-1 antibody, with an RFS lasting more than 3 years. This case suggests that PD-L1 expression and T-cell infiltration could be used as potential biomarkers for PRMS immunotherapy.

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.

Genetic Characterization, Current Model Systems and Prognostic Stratification in PAX Fusion-Negative vs. PAX Fusion-Positive Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and adolescents and accounts for approximately 2% of soft tissue sarcomas in adults. It is subcategorized into distinct subtypes based on histological features and fusion status (PAX-FOXO1/VGLL2/NCOA2). Despite advances in our understanding of the pathobiological and molecular landscape of RMS, the prognosis of these tumors has not significantly improved in recent years. Developing a better understanding of genetic abnormalities and risk stratification beyond the fusion status are crucial to developing better therapeutic strategies. Herein, we aim to highlight the genetic pathways/abnormalities involved, specifically in fusion-negative RMS, assess the currently available model systems to study RMS pathogenesis, and discuss available prognostic factors as well as their importance for risk stratification to achieve optimal therapeutic management.

Rhabdomyosarcoma in Adults: A Retrospective Analysis of Case Records Diagnosed between 1979 and 2018 in Western Denmark

Introduction

Adult rhabdomyosarcoma is a rare tumour that has an inferior survival compared to the paediatric patient population. The reason for this consistently worse outcome remains mostly unknown. It has been suggested that this disparity may be related to biological and/or treatment-related factors, which in the literature has been shown to be distributed differently among paediatric and adult patients. The aim of this study was to clarify treatment outcome and clinicopathological factors for adult patients with rhabdomyosarcoma that were treated in Aarhus, Denmark, since 1979.

Methods

By searching the Aarhus Sarcoma Registers, data for all rhabdomyosarcoma patients, aged 18 years or more, between 1979 and 2018, were retrieved and analysed.

Results

Data from 50 patients were collected. No patients were lost to follow-up. For the entire cohort, 5- and 10-year overall survival rates were 30% and 18%, respectively. The median age was 46.5 years, and the median overall survival was 2.3 years. Tumour histology was embryonal 18%, alveolar 22%, pleomorphic 44%, and not otherwise specified 16%. The tumour site was unfavourable in more than 80% of the patients. Significant factors associated with inferior overall survival were histology and disease stage, although histological subtype was not significant in the multivariate model. Five-year overall survival was 40% for localised disease versus 15% for metastatic disease.

Conclusion

Rhabdomyosarcoma in adults has a poorer prognosis than paediatric rhabdomyosarcoma and other high-grade sarcomas in adults. Adult rhabdomyosarcoma should continue to be treated aggressively, but new and tailored treatment strategies are needed to improve the long-term outcome. Previous predictors of poor survival in paediatric patients were valid in adults except for age, site (favourable versus unfavourable), and tumour size.

Genetic characterisation of adult primary pleomorphic uterine rhabdomyosarcoma and comparison with uterine carcinosarcoma

AIMS

To characterise the genetic alterations in adult primary uterine rhabdomyosarcomas (uRMSs) and to investigate whether these tumours are genetically distinct from uterine carcinosarcomas (UCSs).

METHODS AND RESULTS

Three tumours originally diagnosed as primary adult pleomorphic uRMS were subjected to massively parallel sequencing targeting 468 cancer-related genes and RNA-sequencing. Mutational profiles were compared with those of UCSs (n = 57) obtained from The Cancer Genome Atlas. Sequencing data analyses were performed using validated bioinformatic approaches. Pathogenic TP53 mutations and high levels of genomic instability were detected in the three cases. uRMS1 harboured a likely pathogenic YTHDF2-FOXR1 fusion. uRMS2 harboured a PPP2R1A hotspot mutation and amplification of multiple genes, including WHSC1L1, FGFR1, MDM2, and CCNE1, whereas uRMS3 harboured an FBXW7 hotspot mutation and an ANKRD11 homozygous deletion. Hierarchical clustering of somatic mutations and copy number alterations revealed that these tumours initially diagnosed as pleomorphic uRMSs and UCSs were similar. Subsequent comprehensive pathological re-review of the three uRMSs revealed previously unidentified minute pan-cytokeratin-positive atypical glands in one case (uRMS3), favouring its reclassification as UCS with extensive rhabdomyosarcomatous overgrowth.

CONCLUSIONS

Adult pleomorphic uRMSs harbour TP53 mutations and high levels of copy number alterations. Our findings underscore the challenge in discriminating between uRMS and UCS with rhabdomyosarcomatous differentiation.

Embryonal Rhabdomyosarcoma Presenting as Lung Metastasis in an Adult: An Uncommon Presentation

Rhabdomyosarcoma (RMS) is one of the most common soft tissue sarcomas of adolescents and young adults. Histologically, rhabdomyosarcoma is classified into embryonal, alveolar, pleomorphic, and spindle cell/sclerosing rhabdomyosarcomas with further subcategorization. More than 50% of embryonal rhabdomyosarcoma occur within head and neck. The retroperitoneum and pelvis are less common sites of involvement. Embryonal rhabdomyosarcomas affect mainly, but not exclusively, children between birth and 15 years of age. Alveolar rhabdomyosarcoma tends to affect older patients. The usual metastatic sites include lung, lymph nodes, and bone marrow. We are presenting a case of a 25-year-old male patient with symptoms of breathlessness, easy fatigability, and weight loss. On chest imaging, there were multiple lung nodules. A primary diagnosis of undifferentiated malignant neoplasm was made on lung biopsy. On immunohistochemistry, the malignant cells were positive for myogenin, myoblast determination protein 1 (MyoD1), and desmin. They were negative for neuroendocrine, germ cell, epithelial, melanocytic, and lymphoid markers. Further workup showed an abdominopelvic retroperitoneal mass on abdominal computed tomography (CT) scan. The biopsy on the retroperitoneal mass showed similar morphology and immunohistochemical profile. Unfortunately, the patient's condition deteriorated rapidly in the following weeks, and he passed away.

Non-target genetic manipulation induces rhabdomyosarcoma in KrasPten-driven mouse model of ovarian cancer

Background

Genetically engineered mice are ideal models to advance our understanding the tumorigenesis of ovarian cancer. Our original objective was to establish an ovarian cancer model induced by Kras activation and Pten deletion. However, proficiently establishing the model remains a technical problem, which limits its application.

Methods

We established the Kras activation/Pten deletion-induced mouse model of ovarian cancer by injecting Cre recombinase-expressing adenovirus in the ovarian bursa. PCR analysis, Western blotting, and immunohistochemistry staining were performed to verify the alteration of conditional genes. We detected expression of canonical molecular markers in order to examine the origin of the tumors.

Results

Subcutaneous lumps developed accidentally in mice with ovarian cancer, as early as 2 weeks post in vivo genetic manipulation, far before the destructive growth of ovarian cancer. PCR analysis confirmed the efficient Cre-mediated recombination of Kras and Pten in tumor tissues, which are consistent with the activation of the MAPK and PI3K/Akt/mTOR pathways. Histomorphological and histological analysis showed that the lumps were actually rhabdomyosarcoma (RMS). We confirmed that the leakage of adenovirus transformed healthy adjacent tissues into RMS.

Conclusions

Avoiding accidental exposure of non-target tissues to adenovirus is crucial to successfully establish the ovarian cancer mouse model. Moreover, non-specific genetic manipulations can induce the development of RMS.

High-grade pleomorphic rhabdomyosarcoma in a 60-year-old male: a case report and review of the literature

Rhabdomyosarcoma is an aggressive malignant soft-tissue sarcoma that develop from undifferentiated mesenchymal cells. Less than 1% of all adult solid malignant cancers are sarcomas, and RMSs represent less than 2–5% of adult sarcomas.   RMS is divided into three main subtypes: Embryonal, alveolar and pleomorphic RMS (PRMS).   Most common subtype in adults is PRMS. Most common primary sites are extremities, trunk wall, and genitourinary organs. Metastasis are often found at diagnosis. 5-year overall survival rates were reported in the Surveillance, Epidemiology, and End Results database (SEER) to be 63% for pediatric patients and 27% for adults. Given the rarity of the adult PRMS, variation in its clinical presentation, characteristics of the tumor itself and the prognosis; there are very limited data available to guide the management of adults with PRMS. Herein we present a case report of pleomorphic rhabdomyosarcoma of the right thigh in a 60-year-old male who achieved a long-term survival (30 months) which was accomplished by multimodality treatment including surgery, radiotherapy, and chemotherapy.   

The survival benefit of radiotherapy in localized primary adult rhabdomyosarcoma

AIM

To evaluate the role of radiotherapy (RT) in the treatment of localized primary adult rhabdomyosarcoma (RMS).

METHODS

This retrospective study identified 62 consecutive adult patients with localized primary RMS from January 2000 and July 2016. Local failure-free survival (LFFS), distant metastasis-free survival (DMFS) and overall survival (OS) were analyzed by the Kaplan-Meier method. Multivariate Cox proportional hazards regression models were fit to assess the ability of patient characteristics to predict survival.

RESULTS

With a median follow-up of 33 months (range, 6-195 months), the 5-year LFFS, DMFS and OS of all patients were 64.0%, 50.0% and 45.0%, respectively. RT was administered to 28 patients (45.2%). Patients who received RT had a higher 5-year LFFS (81.7% vs 47.2%), 5-year DMFS (59.4% vs 43.1%) and 5-year OS (57.1% vs 34.8%) compared with patients who did not received RT. In mulitvariate analysis, RT retained significance as an independent predictor of improved LFFS [hazard ratio (HR) = 0.282; 95% confidence interval (CI), 0.095-0.838; P = 0.023], DMFS (HR = 0.289; 95% CI, 0.125-0.991; P = 0.004) and OS (HR = 0.334; 95% CI, 0.153-0.727; P = 0.006).

CONCLUSIONS

RT significantly reduced local recurrence, distant metastasis and tumor mortality compared with no radiotherapy for localized primary adult RMS.

The current landscape of rhabdomyosarcomas: an update

Rhabdomyosarcomas are malignancies associated with a rhabdomyoblastic phenotype which can be demonstrated morphologically or by immunohistochemistry for MYOD1 and myogenin. Rhabdomyosarcomas are currently subdivided into 4 types in the 2013 WHO classification of tumors of soft tissue and bone, including embryonal rhabdomyosarcoma, alveolar rhabdomyosarcoma, spindle cell/sclerosing rhabdomyosarcoma, and pleomorphic rhabdomyosarcoma. Recent studies have significantly impacted this classification with the emergence of three distinct new subtypes of rhabdomyosarcomas, namely rhabdomyosarcoma with MYOD1 mutations, rhabdomyosarcoma with TFCP2 fusions, and rhabdomyosarcoma with VGLL2/NCOA2 fusions. Although all these tumors share the terminology "rhabdomyosarcoma," their morphology, clinical behavior, and underlying molecular alterations are dramatically different. Finally, the presence of a rhabdomyoblastic phenotype within a tumor is by no means a diagnostic of a rhabdomyosarcoma, as this may be seen in many other mesenchymal malignancies, such as mesenchymal chondrosarcomas, malignant peripheral nerve sheaths tumors, and biphenotypic sinonasal sarcomas. In this review, we present the main clinical, morphological, and molecular features of these tumors and discuss the evolution of the current classification.

Rhabdomyosarcoma of the uterus with multiple metastases in a post-menopausal woman

Rhabdomyosarcoma (RMS) is a malignant soft tissue tumor, usually presenting in the head and neck in children, with frequent metastases to the lungs. In this report, we present a rare case of a post-menopausal RMS patient who presented with walking difficulties after hysterectomy. A computerized tomography scan revealed metastases spreading to the mediastinum, retroperitoneum, lungs, liver and bones. On a protocol of Gemcitabine and Carboplatin, the patient showed stability in the dimensions of the masses with significant improvement in her quality of life.

Histiocyte-rich rhabdomyoblastic tumor: rhabdomyosarcoma, rhabdomyoma, or rhabdomyoblastic tumor of uncertain malignant potential? A histologically distinctive rhabdomyoblastic tumor in search of a place in the classification of skeletal muscle neoplasms

Skeletal muscle tumors are traditionally classified as rhabdomyoma or rhabdomyosarcoma. We have identified an unusual adult rhabdomyoblastic tumor not clearly corresponding to a previously described variant of rhabdomyoma or rhabdomyosarcoma, characterized by a very striking proliferation of non-neoplastic histiocytes, obscuring the underlying tumor. Ten cases were identified in nine males and one female with a median age of 43 years (range 23-69 years). Tumors involved the deep soft tissues of the trunk (N = 4), lower limbs (N = 4), and neck (N = 2). Tumors were well-circumscribed, nodular masses, frequently surrounded by a fibrous capsule containing lymphoid aggregates and sometimes calcifications. Numerous foamy macrophages, multinucleated Touton-type giant cells, and sheets/fascicles of smaller, often spindled macrophages largely obscured the underlying desmin, MyoD1, and myogenin-positive rhabdomyoblastic tumor. Cases were wild type for MYOD1 and no other mutations or rearrangements characteristic of a known subtype of rhabdomyoma or rhabdomyosarcoma were identified. Two of four cases successfully analyzed using a next-generation sequencing panel of 170 common cancer-related genes harbored inactivating NF1 mutations. Next-generation sequencing showed no gene fusions. Clinical follow (nine patients; median 9 months; mean 23 months; range 3-124 months) showed all patients received wide excision; four patients also received adjuvant radiotherapy and none received chemotherapy. At the time of last follow-up, all patients were alive and without disease; no local recurrences or distant metastases occurred. We hypothesize that these unusual tumors represent rhabdomyoblastic tumors of uncertain malignant potential. Possibly over time they should be relegated to a new category of skeletal muscle tumors of intermediate (borderline) malignancy.

Pleomorphic Sarcomas: The State of the Art

This article focuses on pleomorphic sarcomas, which are malignant mesenchymal tumors with complex genetic background at the root of their morphologic pleomorphism. They are poorly differentiated tumors that may retain different lines of differentiation, sometimes correlating with clinicopathological or prognostic features. Accurate diagnosis in this group of tumors relies on adequate sampling due to their heterogeneity and assessment with both microscopy and large panels of immunohistochemistry. Molecular analyses have a limited role in their diagnosis as opposed to translocation-related sarcomas but may provide theranostic and important prognostic information in the future.

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.

Clinicopathologic features of 300 rhabdomyosarcomas with emphasis upon differential expression of skeletal muscle specific markers in the various subtypes: A single institutional experience

The present study was aimed at evaluating clinicopathologic and immunohistochemical (IHC) features of 300 rhabdomyosarcomas (RMSs), including differential IHC expression and prognostic value of myogenin and MyoD1 across various subtypes of RMSs. IHC expression of myogenin and MyoD1 was graded on the basis of percentage of tumor cells displaying positive intranuclear immunostaining i.e. grade 1 (1-25%); grade 2 (26-50%); grade 3 (51-76%) and grade 4 (76-100%).Clinical follow-up was available in 238 (79.3%) patients. Various clinicopathologic parameters were correlated with 3-year disease free survival (DFS) and overall survival (OS). There were 140 cases (46.7%) of alveolar RMS (ARMS), 90 of embryonal RMS (ERMS) (30%), 61 (20.3%) of spindle cell/sclerosing RMS and 9 cases (3%) of pleomorphic RMS. Most cases, barring pleomorphic RMSs, occurred in the first two decades (228 cases) (76%), frequently in males, in the head and neck region (126) (42%). By immunohistochemistry, desmin was positive in 292/299 (97.6%) tumors; myogenin in 238/267 (89.1%) and MyoD1 in 192/266 (72.2%) tumors. High myogenin expression (in ≥51% positive tumor cells) was significantly associated with ARMSs (95/121, 78.5%), as compared to other subtypes (48/117, 41%) (p value < 0.001). High MyoD1 expression (≥51% tumor cells) was seen in more cases of pure sclerosing, combined with spindle cell/sclerosing RMSs (10/10, 100%), as compared to the other subtypes (91/141, 67.4%) (p = 0.032). There was no significant difference between high myogenin expression and clinical outcomes. Patients without metastasis and harbouring tumors, measuring ≤5 cm showed a significant increase in OS, with p values = 0.01 and <0.001, respectively. ARMS was the most frequent subtype. There was a significant association between high myogenin expression and ARMSs and high MyoD1 expression and spindle cell/sclerosing RMSs. High myogenin expression did not correlate with clinical outcomes. Patients with smaller sized tumors and without metastasis had significantly better clinical outcomes.

Immunohistochemical Characterization of Sarcomas in Trp53+/- Haploinsufficient Mice

The use of immunohistochemical (IHC) staining in determining and/or confirming the cellular origin of poorly differentiated sarcomas was evaluated in this study. Sarcomatous neoplasms were evaluated in a research study conducted in 2 strains of p53+/- haploinsufficient mice. The most common neoplasms were undifferentiated sarcomas, followed by osteosarcomas and rhabdomyosarcomas (RMSs). The RMSs were poorly differentiated and appeared similar to the pleomorphic, or adult type, RMS of humans. All sarcomas stained positive by IHC for the mesenchymal cell intermediate filament vimentin. The RMSs were identified by positive IHC staining for myogenin, a transcription factor specific to skeletal muscle. Osteosarcomas were easily identifiable on hematoxylin and eosin-stained slides; no generally accepted IHC stain specific for bone is presently available. Some of the undifferentiated sarcomas contained numerous macrophages that stained positive for F4/80, a macrophage marker; the positive-staining cells were considered to be infiltrating macrophages. One-third of the neoplasms observed in this study were associated with subcutaneous implanted electronic microchips used for animal identification. Based upon histopathologic evaluation and IHC staining, it was not possible to distinguish neoplasms associated with subcutaneous microchips from neoplasms not associated with microchips.

Soft Tissue Tumor Immunohistochemistry Update: Illustrative Examples of Diagnostic Pearls to Avoid Pitfalls

CONTEXT

- Current 2013 World Health Organization classification of tumors of soft tissue arranges these tumors into 12 groups according to their histogenesis. Tumor behavior is classified as benign, intermediate (locally aggressive), intermediate (rarely metastasizing), and malignant. In our practice, a general approach to reaching a definitive diagnosis of soft tissue tumors is to first evaluate clinicoradiologic, histomorphologic, and cytomorphologic features of the tumor to generate some pertinent differential diagnoses. These include the potential line of histogenesis and whether the tumor is benign or malignant, and low or high grade. Although molecular/genetic testing is increasingly finding its applications in characterizing soft tissue tumors, currently immunohistochemistry still not only plays an indispensable role in defining tumor histogenesis, but also serves as a surrogate for underlining molecular/genetic alterations. Objective- To provide an overview focusing on the current concepts in the classification and diagnosis of soft tissue tumors, incorporating immunohistochemistry. This article uses examples to discuss how to use the traditional and new immunohistochemical markers for the diagnosis of soft tissue tumors. Practical diagnostic pearls, summary tables, and figures are used to show how to avoid diagnostic pitfalls.

DATA SOURCES

- Data were obtained from pertinent peer-reviewed English-language literature and the authors' first-hand experience as bone and soft tissue pathologists.

CONCLUSIONS

- -The ultimate goal for a pathologist is to render a specific diagnosis that provides diagnostic, prognostic, and therapeutic information to guide patient care. Immunohistochemistry is integral to the diagnosis and management of soft tissue tumors.

Stage 1 embryonal rhabdomyosarcoma of the female genital tract: a retrospective clinical study of nine cases

Background

The aim of the study is to investigate the clinical features, treatments, and prognosis of stage 1 embryonal rhabdomyosarcoma of the female genital tract.

Methods

A retrospective analysis was performed on nine cases of stage 1 embryonal rhabdomyosarcoma of the female genital tract. Clinical characteristics, treatments, recurrence, and prognosis were analyzed.

Results

Of the nine patients with embryonal rhabdomyosarcoma, three originated from the vagina and six from the cervix. For the eight patients who initially received surgery, the median survival time was 88 months. As for the six patients that received adjuvant chemotherapy, five of them who received six or more cycles of treatment achieved tumor-free survival and the survival time ranged from 9 to 228 months. The remaining patient, who declined further treatment after two cycles of chemotherapy, relapsed 11 months following the surgery and died 3 months later. Out of the nine patients, only one was initially treated with chemotherapy, and achieved complete remission, but relapsed 21 months later. After a combination of surgery and chemotherapy, this patient remained tumor-free for total of 117 months.

Conclusions

Patients with early stage embryonal rhabdomyosarcoma of the female genital tract have good prognosis, and the combination of surgery and chemotherapy can lead to better outcomes.

Pseudomyogenic Hemangioendothelioma: A Vascular Tumor Previously Undescribed in the Oral Cavity

The pseudomyogenic hemangioendothelioma (PMH) is a low-grade malignant vascular neoplasm of different tissue planes including skin and soft tissue. Primary tumors in the skeletal muscle and bone have also been diagnosed. The PMH was introduced into the WHO classification of tumors of soft tissue and bone in 2013. This is the first description of oral involvement. A 21-year-old female presented with a 2-month old swelling of her gingiva. The swelling appeared red in color and was soft in consistency. A clinical diagnosis of a pyogenic granuloma was made and an incisional biopsy was submitted for histopathological evaluation. The lesion consisted of a proliferation of spindle and epithelioid looking cells. Cells were arranged in loose fascicles and sheets. Rhabdomyoblast-like cells were also seen. No mitotic figures were present. Lesional cells were reactive to cytokeratin AE1/AE3 and CD31. Lesional cell reactivity to S100 protein, HMB 45, SMA, Desmin and CD34 was negative. Following the diagnosis, a wide excision for clear margins was performed. No recurrence has been reported 2 years since the removal. The PMH is a cutaneous tumor that behaves in an indolent fashion. This is the first report of oral involvement by this neoplasm. Recognition of its histopathological features and immunohistochemical reactivity will prevent misadventures in the diagnosis of oral lesions.

Pleomorphic rhabdomyosarcoma with an impressive response to chemotherapy: case report and review of the literature

PURPOSE

Pleomorphic rhabdomyosarcoma (RMS) represents a rare sarcoma subtype of the adult population. Due to its clinical characteristics, treatment is currently based on the guidelines for adult soft tissue sarcoma therapy. Hence, in the metastatic setting, doxorubicin-containing regimens are used in the sarcoma community, with limited treatment benefit. Scanty published data are available on the efficacy of systemic treatment. Whether treatment response and outcome of these patients could be improved by using pediatric protocols used typically in other RMS subtypes, like embryonal and alveolar RMS, is unclear. We report on an impressive effect of multiagent pediatric chemotherapy in an adult patient with metastatic pleomorphic RMS.

METHODS

We present the case of a 70-year-old man with metastatic pleomorphic RMS of his left thigh. Systemic chemotherapy according to the VAC regimen (vincristine, actinomycin, cyclophosphamide) was initiated. Follow-up clinical and radiologic assessment demonstrated an impressive treatment response.

RESULTS

Sixteen months after primary diagnosis, computed tomography scan shows no signs of tumor progression.

CONCLUSIONS

Our case report emphasizes that multiagent systemic therapy according to pediatric protocols should be considered in adult patients with pleomorphic RMS.

Misdiagnosis of primary pleomorphic rhabdomyosarcoma of the right thigh in a young adult: A case report

Pleomorphic rhabdomyosarcoma (PRMS) is a rare type of soft tissue tumor accounting for <2% of all adult sarcomas. The present study describes a case of a 28-year-old male patient with primary PRMS of the right thigh. The patient was initially diagnosed with a schwannoma and underwent conservative therapy at a local hospital. At the 6-month follow-up, the patient reported a marked increase in the size of the mass. Finally, the patient underwent fine-needle aspiration and total tumor resection. The tumor measured 11×9×5 cm3 in size and was located in the vastus intermedius muscle. According to histological and immunohistochemical findings, a diagnosis of PRMS was confirmed by an expert pathology consultant. Postoperative follow-up at 3 months revealed no evidence of recurrent disease or residual side effects from therapy. However, it is imperative that such cases are closely monitored following surgery, in order to evaluate the long-term efficacy of the procedure, since misdiagnosis may increase the risk of recurrence and metastasis. The present case is noteworthy due to the misdiagnosis of PRMS, the large size of the mass and the young age of the patient.

Case of pleomorphic rhabdomyosarcoma arising on subcutaneous tissue in an adult patient: Review of the published works of 13 cases arising on cutaneous or subcutaneous tissue

Rhabdomyosarcoma (RMS) is a malignant mesenchymal tumor usually occurring in children, young adults, and predominantly arising in the head and neck or deep soft tissue of the extremities. Pleomorphic RMS (PRMS) arising on subcutaneous tissue in an adult patient's trunk is extremely rare. We present a case of primary PRMS occurring on the back of a 50-year-old man. The tumor was diagnosed by histological and immunohistochemical findings of the resected specimen. One month after the surgery, axillary lymph node metastases were found. Subsequently, the patient received three cycles of combined chemotherapy. The rest of those axillary lymph nodes were reduced in size and there was no local recurrence 6 months postoperatively. PRMS is a very rare but aggressive tumor. Thus, it is important to confirm the diagnosis and provide adequate treatments.

Spindle Cell Variant of Embryonal Rhabdomyosarcoma: A Rare Entity with Diagnostic Challenges

The spindle cell variant of embryonal rhabdomyosarcoma is a rare and a better differentiated variant of embryonal rhabdomyosarcoma, having a better prognosis compared to other types of rhabdomyosarcomas. So, it needs to be distinguished from classical forms of the neoplasm. Its morphological resemblance to spindle cell neoplasms like leiomyosarcomas and fibrosarcomas may pose diagnostic difficulties for the pathologist. This problem can be overcome by careful search for rhabdomyoblasts in sections, which are usually few, and Immunohistochemistry for myogenin. In the present case, a 15-year-old female presented with a progressively increasing swelling in the right upper eyelid, which was diagnosed as a rare variant of rhabdomyosarcoma. We have also attempted to discuss its differential diagnosis, and to emphasize the fact that this rare entity may be misdiagnosed.

Treatment Outcome and Predictors of Survival in Thai Adult Rhabdomyosarcoma Cases

BACKGROUND

Adult rhabdomyosarcoma (RMS) is a rare and aggressive disease with limited data compared with pediatric RMS. The goal of this study was to determine the treatment outcome and identify factors related to survival outcome in Thailand.

MATERIALS AND METHODS

Adult patients (≥15 years old) with the pathological diagnosis of RMS between 1985 and 2010 were reviewed. The data were retrospectively reviewed from the pathological results and medical records from Srinagarind Hospital, Khon Kaen University.

RESULTS

A total of 34 patients were identified in the study. The median age at diagnosis was 35.5 years and the most common primary sites were extremity and the head and neck region. The incidence of pleomorphic RMS increased with age and none was found in those aged younger than 20 years old. The median survival time was 9.33 months (95%CI: 5.6-13.1). The 1- and 5- year survival rates were 38.2% (22.3-54.0) and 20.6% (9.1-35.3). On multivariate analysis, age and size of tumor did not predict better outcome while chemotherapy and surgery were significantly associated with longer survival.

CONCLUSIONS

Outcome of adult RMS was poor. Surgery and chemotherapy are s trongly associated with better prognosis and multimodality treatment should be incorporated in the clinic.

Soft tissue tumors of the sinonasal tract

Primary soft tissue tumors arising in the sinonasal tract are rare. While many mesenchymal neoplasms have been reported in the nasal cavity, sinuses, and nasopharynx, few are distinctive to this anatomic region. Some tumor types are relatively more common in this area, such as schwannoma and rhabdomyosarcoma. Nasopharyngeal angiofibroma and sinonasal hemangiopericytoma are unique entities of the sinonasal tract, as well as the recently characterized biphenotypic sinonasal sarcoma. This review discusses the clinical, morphologic, and immunohistochemical features and currently known molecular data of the more frequently encountered soft tissue tumors of the sinonasal tract.

Epithelioid Rhabdomyosarcoma; a case report with immunohistochemical and molecular study

Recently, we encountered a biopsy of epithelioid rabdomyosarcoma with lymph node metastasis. A computed tomography (CT) scan showed number of swollen lymph nodes in the left neck and a huge abdominal mass occupying the right kidney. In the lymph node biopsy, tumor cells showed diffuse sheet-like growth reminiscent of carcinoma and melanoma cells with extensive distribution of coagulation necrosis. Tumor cells had abundant amphophilic cytoplasm and clear large nuclei. Most tumor cells showed severe cytologic atypia manifested in prominent nucleoli and pleomorphic nuclei. Tumor cells were focally positive for desmin. Most tumor cells showed expressons for vimentin, BAF47 (INI-1), and myogenin. On reverse transcriptase polymerase chain reaction (RT-PCR) analysis, tumor cells lacked Myo D1 and PAX3/7-FKHR transcripts and showed myogenin transcripts. On cytogenetic (karyotypic) analysis, tumor cells showed highly complex karyotypes. The patient received various regimens of chemotherapy, but 6 months after the biopsy she died with progression of the tumor. Since consent was not obtained, an autopsy was not performed.

Pancreatic pleomorphic rhabdomyosarcoma

INTRODUCTION

Rhabdomyosarcoma (RMS) is a primary malignancy that arises from the embryonic mesenchyme with the potential to differentiate into skeletal muscle. RMS of the biliary tree is extremely rare. We report a case of an undifferentiated pleomorphic RMS involving the liver and pancreas.

PRESENTATION OF CASE

A 62 year old Caucasian woman with rapidly growing abdominal mass and a history of endometrial adenocarcinoma underwent laparotomy due to compression symptoms and concerns of malignancy. A large mass arising from the pancreas and extending into the liver was identified and resected with a distal pancreatectomy associated with a left lateral liver segmentectomy. A diagnosis of pleomorphic RMS was made from the pathology specimen. Chemotherapy and radiotherapy were also performed. Unfortunately the patient died 2 years following treatment due to recurrence of the disease.

DISCUSSION

P-RMS in the biliary tree is extremely rare (0.5%) and mostly seen in infants and children. Preoperative diagnosis is challenging since the symptoms are unspecific. Preoperative imaging rarely contributes to the final diagnosis. The only possible treatment for adult RMS is surgical resection of the tumor followed by chemotherapy and radiotherapy. Long-term prognosis of P-RMS reported (predominantly of limbs) is poor. To our knowledge, no previous cases of RMS originating from the pancreas have been reported.

CONCLUSION

However RMS is an extremely rare tumor in adults, it should be included in the differential diagnosis of patients with atypical pancreatic and liver lesions.

Nutlin-3 down-regulates retinoblastoma protein expression and inhibits muscle cell differentiation

The p53 tumor suppressor gene plays a critical role in regulation of proliferation, cell death and differentiation. The MDM2 oncoprotein is a major negative regulator for p53 by binding to and targeting p53 for proteasome-mediated degradation. The small molecule inhibitor, nutlin-3, disrupts MDM2-p53 interaction resulting in stabilization and activation of p53 protein. We have previously shown that nutlin-3 activates p53, leading to MDM2 accumulation as concomitant of reduced retinoblastoma (Rb) protein stability. It is well known that Rb is important in muscle development and myoblast differentiation and that rhabdomyosarcoma (RMS), or cancer of the skeletal muscle, typically harbors MDM2 amplification. In this study, we show that nutlin-3 inhibited myoblast proliferation and effectively prevented myoblast differentiation, as evidenced by lack of expression of muscle differentiation markers including myogenin and myosin heavy chain (MyHC), as well as a failure to form multinucleated myotubes, which were associated with dramatic increases in MDM2 expression and decrease in Rb protein levels. These results indicate that nutlin-3 can effectively inhibit muscle cell differentiation.

Myogenic differentiation and histologic grading are major prognostic determinants in retroperitoneal liposarcoma

The aim of the present work was to improve the understanding of the impact of malignancy grade and myogenic/rhabdomyoblastic differentiation on the natural course of retroperitoneal liposarcoma. All consecutive patients affected by primary well-differentiated (WD)/dedifferentiated (DD) retroperitoneal liposarcoma, surgically treated at our institution between January 2002 and December 2011, were retrospectively evaluated. Tumors were stained for mdm2 and 5 myogenic markers (smooth muscle actin-α, h-caldesmon, calponin, desmin, myogenin). The French National Federation of the Centers for the Fight Against Cancer (FNCLCC) grading system was applied. Overall survival, crude cumulative incidence of local recurrence, and distant metastases were calculated. Multivariable analyses were carried out. A total of 144 patients were identified. Median follow-up was 68 months (interquartile range: 46 to 104 mo). Fifty-two patients were affected by WD/G1 and 92 by DD liposarcoma. Among the latter, 60 were grade G2 and 32 G3. Myogenic differentiation was present in 54 cases (8/52 WD/G1, 27/60 DD/G2, 18/32 DD/G3). Seven cases had a rhabdomyoblastic DD component (1/60 DD/G2 and 6/32 DD/G3). Five-year overall survival rates were 93%, 57%, and 21% for WD/G1 liposarcoma, G2 DD, and G3 DD liposarcoma, respectively, and 75%, 42%, and 29% for liposarcoma without myogenic differentiation, with myogenic differentiation, with rhabdomyoblastic differentiation, respectively (P<0.001). Of note, 5/6 patients affected by G3 DD liposarcoma with a rhabdomyoblastic component died within 8 months. FNCLCC grade and myogenic differentiation significantly predicted the outcome of retroperitoneal liposarcoma. These should be factored into treatment decision-making and possibly used to stratify patients in clinical trials.

Bone marrow metastasis of rhabdomyosarcoma mimicking acute leukemia: a case report and review of the literature

Bone marrow metastasis of rhabdomyosarcoma has been reported to be difficult to distinguish from acute leukemia. We herein describe a case of rhabdomyosarcoma with bone marrow metastasis mimicking acute lymphoblastic leukemia. A 29-year-old woman was admitted with thrombocytopenia, blast-like cells in the peripheral blood and a coagulation disorder. Bone marrow aspirates showed 94.8% blast-like cell infiltration (CD45(-), myeloperoxidase(-), and CD56(+)), and CT scan revealed the presence of an infiltrating mass in the nasal cavity. Based on a biopsy of the nasal cavity, the patient was diagnosed with rhabdomyosarcoma exhibiting bone marrow metastasis. She received chemotherapy, followed by radiation therapy, and has since remained alive for 26 months, as of the last follow-up.

The Application of Immunohistochemical Biomarkers in Urologic Surgical Pathology

Context

Tumors of the genitourinary tract can be diagnostically challenging, particularly in core biopsies and cystoscopic biopsies with limited material. Immunohistochemistry is a valuable tool to use when morphology alone is insufficient for diagnosis.

Objectives

To review tumors and benign lesions of the kidney, urinary bladder, prostate gland, testis, and paratesticular structures with an emphasis on difficult differential diagnoses, as well as staining patterns in normal tissue. Recommended immunohistochemical stain panels are discussed that can assist in the diagnostic workup.

Data Sources

Review of current literature.

Conclusions

Immunohistochemistry is a valuable tool, assisting in the diagnosis of problematic tumors and benign lesions of the genitourinary tract.