Central nervous system relapse of rhabdomyosarcoma

An Evaluation of Risk Factors for Intracranial Metastases of Sarcomas: A Systematic Review and Meta-Analysis

INTRODUCTION

Sarcomas, a group of neoplasms comprising both tissue and bone soft tissue tumors, has an increasing prevalence in recent years. Prognosis significantly hinges on early detection, and if not detected early, may consequently metastasize. This review will be the first systematic review and meta-analysis characterizing the presentation and progression of brain metastases from bone and soft tissue cancers.

METHODS

The PubMed, Scopus, and Web of Science databases were queried to identify studies reporting the incidence of intracranial brain metastases from primary sarcoma to the present. Abstract and full-text screening of 1822 initial articles returned by preliminary search yielded 28 studies for inclusion and data extraction. Qualitative assessment of the studies was conducted in accordance with the Newcastle-Ottawa Scale criteria. Meta-analyses were applied to assess risk factors on outcomes.

RESULTS

The average age within the cohort was 27.9 years with a male and female prevalence of 59.1% and 40.9%, respectively. The odds ratio for living status (dead/alive) was calculated for several risk factors - male/female [OR 1.14, 95% CI 0.62, 2.07], single/multiple metastases [OR 0.67, 95% CI 0.35, 1.28], lung metastases/not [OR 1.63, 95% CI 0.85, 3.13], surgery/no surgery [OR 0.49, 95% CI 0.20, 1.21]. The standardized mean differences for duration from diagnoses to metastases were likewise analyzed - male/female [SMD 0.13, 95% CI -0.15, 0.42], single/multiple metastases [SMD 0.11, 95% CI -0.20, 0.42], lung metastases/not [SMD -0.03, 95% CI -0.38, 0.32], surgery/no surgery [SMD 0.45, 95% CI -0.18, 1.09]. The standardized mean differences for duration from metastases to death were analyzed - lung metastases/not [SMD 0.43, 95% CI -0.08, 0.95].

CONCLUSIONS

Our study observed no statistically significant differences in mortality rate among several patient risk factors. Consequentially, there lacks a clear answer as to whether or not an association between mortality rates exists with these patient factors. As such, it is important to continue research in brain-metastasizing sarcomas despite their relative rarity.

Brain metastases of sarcoma: a rare phenomenon in rare tumours

The usual site for distant metastases of sarcoma is lungs, while brain metastasis (BM) occurs much less frequently and usually late in the disease progression. Despite the advancement in cancer treatment, the outcome for patients with brain metastasis is poor, and their lifespan is short. The frequency of BM in sarcoma seems to be affected by the location and histology of the primary tumour. Sarcoma subtypes with a high propensity for brain metastasis are ASPS, leiomyosarcoma and osteosarcoma. There are no clear guidelines for the treatment of sarcoma brain metastasis. However, therapeutic options include surgery, radiotherapy and chemotherapy, and are often combined. Targeted therapies are a promising treatment option for sarcoma but require investigation in patients with BM. The following review presents the data on sarcoma brain metastasis incidence, treatment and prognosis.

Recent advancements in the B7/CD28 immune checkpoint families: new biology and clinical therapeutic strategies

The B7/CD28 families of immune checkpoints play vital roles in negatively or positively regulating immune cells in homeostasis and various diseases. Recent basic and clinical studies have revealed novel biology of the B7/CD28 families and new therapeutics for cancer therapy. In this review, we discuss the newly discovered KIR3DL3/TMIGD2/HHLA2 pathways, PD-1/PD-L1 and B7-H3 as metabolic regulators, the glycobiology of PD-1/PD-L1, B7x (B7-H4) and B7-H3, and the recently characterized PD-L1/B7-1 cis-interaction. We also cover the tumor-intrinsic and -extrinsic resistance mechanisms to current anti-PD-1/PD-L1 and anti-CTLA-4 immunotherapies in clinical settings. Finally, we review new immunotherapies targeting B7-H3, B7x, PD-1/PD-L1, and CTLA-4 in current clinical trials.

Quantitative proteomics identifies and validates urinary biomarkers of rhabdomyosarcoma in children

BACKGROUND

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma with poor prognosis in children. The 5-year survival rate for early RMS has improved, whereas it remains unsatisfactory for advanced patients. Urine can rapidly reflect changes in the body and identify low-abundance proteins. Early screening of tumor markers through urine in RMS allows for earlier treatment, which is associated with better outcomes.

METHODS

RMS patients under 18 years old, including those newly diagnosed and after surgery, were enrolled. Urine samples were collected at the time points of admission and after four cycles of chemotherapy during follow-up. Then, a two-stage workflow was established. (1) In the discovery stage, differential proteins (DPs) were initially identified in 43 RMS patients and 12 healthy controls (HCs) using a data-independent acquisition method. (2) In the verification stage, DPs were further verified as biomarkers in 54 RMS patients and 25 HCs using parallel reaction monitoring analysis. Furthermore, a receiver operating characteristic (ROC) curve was used to construct the protein panels for the diagnosis of RMS. Gene Ontology (GO) and Ingenuity Pathway Analysis (IPA) software were used to perform bioinformatics analysis.

RESULTS

A total of 251 proteins were significantly altered in the discovery stage, most of which were enriched in the head, neck and urogenital tract, consistent with the most common sites of RMS. The most overrepresented biological processes from GO analysis included immunity, inflammation, tumor invasion and neuronal damage. Pathways engaging the identified proteins revealed 33 common pathways, including WNT/β-catenin signaling and PI3K/AKT signaling. Finally, 39 proteins were confirmed as urinary biomarkers for RMS, and a diagnostic panel composed of 5 candidate proteins (EPS8L2, SPARC, HLA-DRB1, ACAN, and CILP) was constructed for the early screening of RMS (AUC: 0.79, 95%CI = 0.66 ~ 0.92).

CONCLUSIONS

These findings provide novel biomarkers in urine that are easy to translate into clinical diagnosis of RMS and illustrate the value of global and targeted urine proteomics to identify and qualify candidate biomarkers for noninvasive molecular diagnosis.

Phase 1 study of intraventricular 131I-omburtamab targeting B7H3 (CD276)-expressing CNS malignancies

BACKGROUND

The prognosis for metastatic and recurrent tumors of the central nervous system (CNS) remains dismal, and the need for newer therapeutic targets and modalities is critical. The cell surface glycoprotein B7H3 is expressed on a range of solid tumors with a restricted expression on normal tissues. We hypothesized that compartmental radioimmunotherapy (cRIT) with the anti-B7H3 murine monoclonal antibody omburtamab injected intraventricularly could safely target CNS malignancies.

PATIENTS AND METHODS

We conducted a phase I trial of intraventricular ¹³¹I-omburtamab using a standard 3 + 3 design. Eligibility criteria included adequate cerebrospinal fluid (CSF) flow, no major organ toxicity, and for patients > dose level 6, availability of autologous stem cells. Patients initially received 74 MBq radioiodinated omburtamab to evaluate dosimetry and biodistribution followed by therapeutic ¹³¹I-omburtamab dose-escalated from 370 to 2960 MBq. Patients were monitored clinically and biochemically for toxicity graded using CTCAEv 3.0. Dosimetry was evaluated using serial CSF and blood sampling, and serial PET or gamma-camera scans. Patients could receive a second cycle in the absence of grade 3/4 non-hematologic toxicity or progressive disease.

RESULTS

Thirty-eight patients received 100 radioiodinated omburtamab injections. Diagnoses included metastatic neuroblastoma (n = 16) and other B7H3-expressing solid tumors (n = 22). Thirty-five patients received at least 1 cycle of treatment with both dosimetry and therapy doses. Acute toxicities included < grade 4 self-limited headache, vomiting or fever, and biochemical abnormalities. Grade 3/4 thrombocytopenia was the most common hematologic toxicity. Recommended phase 2 dose was 1850 MBq/injection. The median radiation dose to the CSF and blood by sampling was 1.01 and 0.04 mGy/MBq, respectively, showing a consistently high therapeutic advantage for CSF. Major organ exposure was well below maximum tolerated levels. In patients developing antidrug antibodies, blood clearance, and therefore therapeutic index, was significantly increased. In patients receiving cRIT for neuroblastoma, survival was markedly increased (median PFS 7.5 years) compared to historical data.

CONCLUSIONS

cRIT with ¹³¹I-omburtamab is safe, has favorable dosimetry and may have a therapeutic benefit as adjuvant therapy for B7-H3-expressing leptomeningeal metastases.

TRIAL REGISTRATION

clinicaltrials.gov NCT00089245, August 5, 2004.

Immune checkpoint of B7-H3 in cancer: from immunology to clinical immunotherapy

Immunotherapy for cancer is a rapidly developing treatment that modifies the immune system and enhances the antitumor immune response. B7-H3 (CD276), a member of the B7 family that plays an immunoregulatory role in the T cell response, has been highlighted as a novel potential target for cancer immunotherapy. B7-H3 has been shown to play an inhibitory role in T cell activation and proliferation, participate in tumor immune evasion and influence both the immune response and tumor behavior through different signaling pathways. B7-H3 expression has been found to be aberrantly upregulated in many different cancer types, and an association between B7-H3 expression and poor prognosis has been established. Immunotherapy targeting B7-H3 through different approaches has been developing rapidly, and many ongoing clinical trials are exploring the safety and efficacy profiles of these therapies in cancer. In this review, we summarize the emerging research on the function and underlying pathways of B7-H3, the expression and roles of B7-H3 in different cancer types, and the advances in B7-H3-targeted therapy. Considering different tumor microenvironment characteristics and results from preclinical models to clinical practice, the research indicates that B7-H3 is a promising target for future immunotherapy, which might eventually contribute to an improvement in cancer immunotherapy that will benefit patients.

Metastatic primary brain rhabdomyosarcoma in a pediatric patient: illustrative case

BACKGROUND

Primary intracranial rhabdomyosarcoma is an extraordinarily rare malignant tumor, with even fewer presenting with distant metastasis. To date, only five cases, including the one presented here, have been reported to present metastatic activity.

OBSERVATIONS

A 12-year-old boy presented with a few days of headache, nausea, vomiting, but no neurological deficit. Brain computed tomography and magnetic resonance imaging demonstrated hydrocephalus and a cystic lesion with left parieto-occipital extension. After resection, pathology reported primary rhabdomyosarcoma, with positive desmin and myogenin on immunohistochemistry. The patient presented with pulmonary metastasis. The patient had an overall survival of 21 months after diagnosis with optimal treatment.

LESSONS

Rhabdomyosarcoma is a malignant neoplasm arising from undifferentiated skeletal muscle cells, with morphological, immunohistochemical, ultrastructural, or molecular genetic evidence of primary skeletal muscle differentiation. It presents with a rapidly worsening clinical course and the final outcome is poor. Treatment is widely based on protocols that have been proven to be effective in extracranial versions of these tumors, although repeatedly ineffective. Primary brain rhabdomyosarcoma poses a diagnostic challenge because of its infrequent presentation, grade of undifferentiation and tumor heterogeneity. Immunohistochemical and genetic testing have proven to be useful tools for diagnosis.

Guidelines for magnetic resonance imaging in pediatric head and neck pathologies: a multicentre international consensus paper

The use of standardized imaging protocols is paramount in order to facilitate comparable, reproducible images and, consequently, to optimize patient care. Standardized MR protocols are lacking when studying head and neck pathologies in the pediatric population. We propose an international, multicenter consensus paper focused on providing the best combination of acquisition time/technical requirements and image quality. Distinct protocols for different regions of the head and neck and, in some cases, for specific pathologies or clinical indications are recommended. This white paper is endorsed by several international scientific societies and it is the result of discussion, in consensus, among experts in pediatric head and neck imaging.

Radiation Therapy in the Treatment of Head and Neck Rhabdomyosarcoma

The use of radiation therapy is an important part of multimodality treatment for rhabdomyosarcoma. The specific doses, treatment volumes, and techniques used in radiation therapy can vary dramatically based upon a number of factors including location, tumor size, and molecular characteristics, resulting in complex decisions in treatment planning. This article reviews the principles of evaluation and management for head and neck rhabdomyosarcoma including a summary of the historical studies upon which current management is based.

Parameningeal alveolar rhabdomyosarcoma in a child

This is the case of a parameningeal alveolar rhabdomyosarcoma (ARMS) in a 13-year-old boy who presented with painless loss of vision in the right eye, but very few other physical signs. The ARMS diagnosis was confirmed with imaging and molecular characterisation of the tumour. Despite tolerating the initial chemotherapy and radiotherapy regimens, there was leptomeningeal recurrence and the patient unfortunately passed away. Parameningeal ARMS occurs in an area of the body, which leads to a wide variety of possible presenting symptoms, creating a long list of differentials that can delay treatment. This tumour subtype has a poor prognosis, and due to the location of the tumour around vital structures in the head, treatment toxicities must be taken into account. This highlights the necessity for having a strong index of suspicion for this tumour in atypical presentations in children, and the necessity for prompt treatment to prevent leptomeningeal disease from occurring.

Rhabdomyosarcoma

Rhabdomyosarcoma is a heterogeneous disease both in presentation and histology. Improvements in a multimodality therapy resulted in the improved overall survival for patients with a low-risk and intermediate-risk disease but not for patients with a metastatic disease. We reviewed and contrasted the North American and European practice patterns, though ultimately the principles of staging, surgery, radiation therapy, and chemotherapy are similar in both Children's Oncology Group and International Society of Paediatric Oncology treatment approaches. Efforts are underway to investigate improved local control rates in higher risk patients using radiation dose escalation strategies, and delayed primary excision in select cases. The prognostic significance of imaging-based chemotherapy response, proton therapy, novel biomarkers, and targeted drugs will be determined in upcoming clinical trials.

Alveolar rhabdomyosarcoma metastatic to the brain

Alveolar rhabdomyosarcoma (ARMS) has a predilection for the peripheral extremities, and brain metastases are rare, with only a few cases reported after the initial diagnosis. We present a 22-year-old male patient with a right orbital-ethmoidal ARMS who presented with a recurrence to the brain 1 year after the initial diagnosis. He was referred to our institution due to acute neurological deterioration. A brain MRI was performed, showing an enhancing bilateral parafalcine lesion centred about the bilateral cingulate gyri with extension into the corpus callosum. The patient was taken to the operating room for a stereotactic biopsy under general anaesthesia, which was compatible with metastatic ARMS. Our case is exceedingly rare, considering the initial diagnosis of an orbital/ethmoidal ARMS, its subsequent metastasis to the brain and its clinical sequelae after a biopsy. Prognosis after cerebral metastatic ARMS is dismal, with most patients expiring due to central nervous system metastatic disease.

Clinical trial of proton craniospinal irradiation for leptomeningeal metastases

BACKGROUND

Leptomeningeal metastases (LM) are associated with limited survival and treatment options. While involved-field radiotherapy is effective for local palliation, it lacks durability. We evaluated the toxicities of proton craniospinal irradiation (CSI), a treatment encompassing the entire central nervous system (CNS) compartment, for patients with LM from solid tumors.

METHODS

We enrolled patients with LM to receive hypofractionated proton CSI in this phase I prospective trial. The primary endpoint was to describe treatment-related toxicity, with dose-limiting toxicity (DLT) defined as any radiation-related grade 3 non-hematologic toxicity or grade 4 hematologic toxicity according to the Common Terminology Criteria for Adverse Events that occurred during or within 4 weeks of completion of proton CSI. Secondary endpoints included CNS progression-free survival (PFS) and overall survival (OS).

RESULTS

We enrolled 24 patients between June 2018 and April 2019. Their median follow-up was 11 months. Twenty patients were evaluable for protocol treatment-related toxicities and 21 for CNS PFS and OS. Two patients in the dose expansion cohort experienced DLTs consisted of grade 4 lymphopenia, grade 4 thrombocytopenia, and/or grade 3 fatigue. All DLTs resolved without medical intervention. The median CNS PFS was 7 months (95% CI: 5-13) and the median OS was 8 months (95% CI: 6 to not reached). Four patients (19%) were progression-free in the CNS for more than 12 months.

CONCLUSION

Hypofractionated proton CSI using proton therapy is a safe treatment for patients with LM from solid tumors. We saw durable disease control in some patients.

Surgical outcome and graded prognostic assessment of patients with brain metastasis from adult sarcoma: multi-institutional retrospective study in Japan

BACKGROUND

Brain metastasis (BM) is an uncommon complication of sarcomas with a poor prognosis. Little information is available about the feasibility and prognostic factors of surgical resection of BM from sarcomas.

METHODS

This study involved a retrospective analysis of 22 patients with BM from sarcomas who underwent resection at six institutes in Japan. Prognostic factors were analyzed to develop a graded prognostic assessment (GPA) using the log-rank test and Cox regression analysis. For validation of this GPA, we collected data on 100 surgical cases from 48 published reports.

RESULTS

Postoperative Karnofsky Performance Status (KPS) improved in 50% of our patients. Median overall survival (OS) was 21 months. Multivariate analysis showed age and alveolar soft part sarcoma (ASPS) were significant preoperative prognostic factors (P < 0.05). RTOG-RPA classification had no significant prognostic value. We developed a GPA system for OS after resection of BM. A score of 0 was assigned to patients aged 18-29 years with non-ASPS, 2 to patients aged 18-29 years with ASPS or 30-76 years with non-ASPS, and 4 to patients aged 30-76 years with ASPS. Median OS for patients with GPA scores of 0, 2, and 4 were 6.5, 16.0, and 44.0 months, respectively (P = 0.002). The results were validated by the data of 100 cases compiled (P < 0.001).

CONCLUSION

Median OS of patients with BM from sarcomas was comparable to that from carcinomas after resection. A new sarcoma-specific GPA may help patients and clinicians to select resection as an option for treatment of BM from sarcomas.

MRI of Rhabdomyosarcoma and Other Soft-Tissue Sarcomas in Children

Soft-tissue sarcomas in children comprise a heterogeneous group of entities with variable manifestation depending on the age of the patient and the location of the tumor. MRI is the modality of choice for evaluating musculoskeletal soft-tissue tumors and plays a paramount role in both initial diagnosis and assessment of tumor response during and after treatment. Conventional MRI sequences, such as T1- and T2-weighted imaging, offer morphologic information, which is important for localizing the lesion and describing anatomic relationships but not accurate for determining its malignant or benign nature and may be limited in differentiating tumor response from therapy-related changes. Advanced multiparametric MRI offers further functional information that can help with these tasks by using different imaging sequences and biomarkers. The authors present the role of MRI in rhabdomyosarcoma and other soft-tissue sarcomas in children, emphasizing a multiparametric approach with focus on the utility and potential added value of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI in characterization and staging, determination of pretreatment extent, and evaluation of tumor response and recurrence after treatment. ^©RSNA, 2020.

B7-H3-targeted Radioimmunotherapy of Human Cancer

BACKGROUND

Targeted Radioimmunotherapy (RIT) is an attractive approach to selectively localize therapeutic radionuclides to malignant cells within primary and metastatic tumors while sparing normal tissues from the effects of radiation. Many human malignancies express B7-H3 on the tumor cell surface, while expression on the majority of normal tissues is limited, presenting B7-H3 as a candidate target for RIT. This review provides an overview of the general principles of targeted RIT and discusses publications that have used radiolabeled B7-H3-targeted antibodies for RIT of cancer in preclinical or clinical studies.

METHODS

Databases including PubMed, Scopus, and Google Scholar were searched for publications through June 2018 using a combination of terms including "B7-H3", "radioimmunotherapy", "targeted", "radiotherapy", and "cancer". After screening search results for relevancy, ten publications were included for discussion.

RESULTS

B7-H3-targeted RIT studies to date range from antibody development and assessment of novel Radioimmunoconjugates (RICs) in animal models of human cancer to phase II/III trials in humans. The majority of clinical studies have used B7-H3-targeted RICs for intra- compartment RIT of central nervous system malignancies. The results of these studies have indicated high tolerability and favorable efficacy outcomes, supporting further assessment of B7-H3-targeted RIT in larger trials. Preclinical B7-H3-targeted RIT studies have also shown encouraging therapeutic outcomes in a variety of solid malignancies.

CONCLUSION

B7-H3-targeted RIT studies over the last 15 years have demonstrated feasibility for clinical development and support future assessment in a broader array of human malignancies. Future directions worthy of exploration include strategies that combine B7-H3- targeted RIT with chemotherapy or immunotherapy.

Radiotherapy in Leptomeningeal Disease: A Systematic Review of Randomized and Non-randomized Trials

Background: Leptomeningeal disease (LMD), also known as neoplastic meningitis, leptomeningeal carcinomatosis, or carcinomatous meningitis, is a rare cancer complication occurring in ~5% of cases and ultimately leads to significant morbidity and mortality. In the modern era, incidence of this condition continues to rise with longer survival of patients with advanced and even metastatic disease due to continued improvements in systemic therapies that are providing prolonged control of distant disease, but with limited effect in the central nervous system (CNS). Typical treatment strategies include optimal systemic therapy for the primary disease, as well as neuroaxis directed therapies, which may include intrathecal chemotherapy (ITC) or radiotherapy (RT). Methods: A systematic review of radiotherapy for LMD was performed. Medline, EMBASE, and Cochrane databases were searched from 1946 to 2018 for clinical trials, retrospective/prospective reviews, and case series with ≥2 human subjects that used radiation therapy techniques in the treatment of LMD. The outcome measures of interest included: characteristics of trial participants, inclusion/exclusion criteria, study type, number of participants, primary cancer histology, type of intervention for LMD, survival results if reported, length of follow up, and study conclusion. Results: Of 547 unique citations, 62 studies met the pre-specified eligibility criteria. These studies included 36 retrospective cohorts, 11 prospective series, 12 case series, and a single citation of guidelines, NCDB analysis, and a randomized control trial. Owing to study heterogeneity, meta-analyses of the endpoint data could not be performed. Conclusions: LMD is a devastating complication of cancer with reported survivals ranging from 2 to 4 months. Based on this systematic review, the recommendation for the treatment of LMD is for multimodality discussion of cases and treatment, including the use of radiotherapy, for LMD. However, with continued advances in systemic therapy as well as imaging advances, the landscape of LMD is evolving rapidly and the role of RT will likely also continue to evolve and advance. There is limited high-quality evidence to guide the optimal use of RT for the treatment of LMD, and there is a great need for prospective, histology specific investigation of the role of radiotherapy for LMD in the era of modern systemic therapies.

Central Nervous System Involvement of Rhabdomyosarcoma: A Single Institution Experience

The incidence of central nervous system (CNS) involvement in patients with rhabdomyosarcoma (RMS) is low, and the outcome is dismal. We present a single institution analysis of CNS involvement of pediatric RMS. In 59 patients, the prevalence of CNS involvement was 11.9% (7 patients), higher than prior reports. Of the 6 deaths from disease, all had rapid progression, with a median survival of 14 days. The higher incidence could be secondary to treatment modifications or more sensitive detection. These findings are useful for decisions at the time of CNS involvement and could lead to modifications for future RMS clinical trials.

Aggressive embryonal rhabdomyosarcoma in a 3-month-old boy: A clinical and molecular analysis

Rhabdomyosarcoma (RMS) represents the most common soft tissue sarcoma in the pediatric age group. While RMS has been traditionally classified on the basis of its histological appearance (with embryonal and alveolar being most common), it is now clear that the PAX-FOXO1 fusion product drives prognosis. We report here a case of pelvic embryonal RMS in a 3-month-old male who was subsequently found to have developed brain metastases during the course of chemotherapy. Cytogenetic analysis of the brain metastases at the time of autopsy as well as next-generation sequencing analysis revealed a reciprocal translocation involving the SH3 domain containing ring finger 3 gene (SH3RF3, on chromosome 2q13) and the Lipase C gene (LIPC, on chromosome 15q21.3). Due to the poor quality of the pretreatment and postresection samples, cytogenetics and NGS analysis looking for the presence of this balanced translocation in these specimens could not be performed. To the authors' knowledge, this translocation has never been described in RMS. Further studies are needed to determine the biological and clinical implications of this novel translocation.

Cytologic Diagnosis of Metastatic Alveolar Rhabdomyosarcoma in Cerebrospinal Fluid: A Case Report

Rhabdomyosarcoma is a malignant soft tissue tumor which shows skeletal muscle differentiation. Leptomeningeal metastasis can occur as a late complication, but currently there are no reports that have documented the cytologic features in cerebrospinal fluid (CSF). We report a case of metastatic alveolar rhabdomyosarcoma diagnosed in the CSF of a 28-year-old male who was originally diagnosed with rhabdomyosarcoma on the neck, and that went through systemic therapy. The tumor was positive for anaplastic lymphoma kinase, but progressed despite additional therapy with crizotinib. The CSF specimen revealed small round cells, large atypical cells with abundant cytoplasm and eccentric nuclei, and cells with horseshoe-shaped nuclei. These cytologic findings were in agreement with previous literature and well-correlated with histopathology. This is the first report to document the cytologic feature of rhabdomyosarcoma in CSF. In many cases it is difficult to perform ancillary tests in a CSF specimen and cytopathologists should be aware of the cytomorphologic characteristics to avoid misdiagnosis.