Features Of Rhabdomyosarcoma Research Articles

Fisher discriminant model based on LASSO logistic regression for computed tomography imaging diagnosis of pelvic rhabdomyosarcoma in children

Computed tomography (CT) has been widely used for the diagnosis of pelvic rhabdomyosarcoma (RMS) in children. However, it is difficult to differentiate pelvic RMS from other pelvic malignancies. This study aimed to analyze and select CT features by using least absolute shrinkage and selection operator (LASSO) logistic regression and established a Fisher discriminant analysis (FDA) model for the quantitative diagnosis of pediatric pelvic RMS. A total of 121 pediatric patients who were diagnosed with pelvic neoplasms were included in this study. The patients were assigned to an RMS group (n = 36) and a non-RMS group (n = 85) according to the pathological results. LASSO logistic regression was used to select characteristic features, and an FDA model was constructed for quantitative diagnosis. Leave-one-out cross-validation and receiver operating characteristic (ROC) curve analysis were used to evaluate the diagnostic ability of the FDA model. Six characteristic variables were selected by LASSO logistic regression, all of which were CT morphological features. Using these CT features, the following diagnostic models were established: (RMS group){G}_{1}=-14.283+6.613{x}_{1}+5.333{x}_{2}+5.753{x}_{3}+12.361{x}_{4}+8.095{x}_{5}-0.715{x}_{6}; (Non-RMS group){G}_{2}=-2.008+3.539{x}_{1}+1.080{x}_{2}+1.154{x}_{3}+2.307{x}_{4}+1.656{x}_{5}+1.380{x}_{6}, where {x}_{1}, {x}_{2}, … and {x}_{6} are lower than normal muscle density (1 = yes; 0 = no), multinodular fusion (1 = yes; 0 = no), enhancement at surrounding blood vessels (1 = yes; 0 = no), heterogeneous progressive centripetal enhancement (1 = yes; 0 = no), ring enhancement (1 = yes; 0 = no), and hemorrhage (1 = yes; 0 = no), respectively. The calculated area under the ROC curve (AUC) of the model was 0.992 (0.982–1.000), with a sensitivity of 94.4%, a specificity of 96.5%, and an accuracy of 95.9%. The calculated sensitivity, specificity and accuracy values were consistent with those from cross-validation. An FDA model based on the CT morphological features of pelvic RMS was established and could provide an easy and efficient method for the diagnosis and differential diagnosis of pelvic RMS in children.

Racial and ethnic differences in presentation and clinical outcomes for pediatric rhabdomyosarcoma (RMS).

10017 Background: Race and ethnicity are recognized risk factors for many cancer types, including several pediatric cancers. Though racial and ethnic disparities in the presentation, treatment, and survival of certain cancers have been widely demonstrated, there is conflicting evidence about whether such disparities exist in RMS, the most common pediatric soft tissue sarcoma. Understanding the role of race and ethnicity in the presentation, treatment, and prognosis of RMS is important to promote improved survival in patients of all racial and ethnic groups. Methods: Patient, tumor, and treatment characteristics of patients enrolled on Children’s Oncology Group studies D9602, D9802, D9803, ARST0331, ARST0431, ARST0531, and ARST08P1 were compared across racial and ethnic groups using a chi-square test. Significant characteristics underwent pairwise analysis, comparing the Non-Hispanic Black (NHB) and Non-Hispanic White (NHW) groups. Outcome analyses were performed using the Kaplan-Meier method and Wilcoxon signed-rank test. Results: Race and ethnicity incidence among the 2157 study patients were as follows: 8 (0.4%) American Indian or Alaska Native, 56 (2.6%) Asian, 271 (12.6%) Hispanic, 4 (0.2%) Native American or other Pacific Islander, 275 (12.8%) Non-Hispanic Black, 1335 (61.9%) Non-Hispanic White, and 208 (9.6%) unknown. Thirteen patient and tumor factors relating to presentation and treatment were evaluated for differences by race and ethnicity; the following five were significant: age, IRS group, tumor invasiveness, metastatic disease, and FOXO1 fusion partner. Pairwise comparison of NHB and NHW patients for these factors demonstrated that NHBs are more likely than NHWs to present at age 10 years or greater (p = 0.002) and that NHB patients are more likely to present with invasive tumors (p = 0.012). Incidence of metastatic disease at diagnosis was not significantly different between the groups (p = 0.202). No differences in treatment, including extent of surgical resection (p = 0.259) or use of radiation therapy (p = 0.920), were found. Neither event free survival nor overall survival were significantly different across the entire cohort (EFS p = 0.457, OS p = 0.159) or in subset analysis by risk group (low risk: EFS p = 0.856, OS p = 0.558; intermediate risk: EFS p = 0.907, OS p = 0.493; high risk: EFS p = 0.218, OS p = 0.397), by age (< 1y: EFS p = 0.489, OS p = 0.546; 1-9y: EFS p = 0.417, OS p = 0.112; ≥10y: EFS p = 0.556, OS p = 0.609), in invasive tumors (EFS p = 0.704, OS p = 0.872), or in metastatic disease (EFS p = 0.270, OS p = 0.373). Conclusions: These data indicate that while differences in the presenting features of RMS exist between racial groups, with NHB patients exhibiting higher risk features, patients treated on these clinical trials did not experience differences in outcomes by racial group. This suggests NHB patients may experience a survival benefit from clinical trial enrollment.

Organ preserving laparoscopic resection of bladder rhabdomyosarcoma in a child

Bladder rhabdomyosarcoma (RMS) in children, at presentation are often large, situated in close proximity to vital structures. This makes the surgical resection challenging. Hence, chemoradiotherapy is often used first. For those tumors which are amenable for resection, laparoscopy can serve as a better alternative. A 5-year-old boy presented with lump in the abdomen. MRI revealed a solid tumor of size 4.8 × 4.3 × 5.3 cms arising from dome of bladder. Tru-cut biopsy of the tumor showed features of RMS, after which VAC (Vincristine, Actinomycin-D, Cyclophosphamide) chemotherapy was started. By the end of two cycles of chemotherapy, patient required hospital admission multiple times due to chemotherapy toxicity. Review imaging of the tumor showed >60% reduction in size. Laparoscopic bladder preserving partial cystectomy was done. Post-operatively patient was discharged after six days. During follow-up, patient had no urinary symptoms. The resected specimen had tumor cells at inferior margin. Adjuvant chemotherapy course was completed. Two years after the surgery, patient remains free of recurrence. Laparoscopy serves as a good alternative to open surgery for bladder RMS surgeries. Laparoscopic bladder preserving surgery can be done with good access, limiting the operative morbidity. Patients can benefit from smaller scars and speedy post-operative recovery.

A Rare Presentation of a Large Embryonal Rhabdomyosarcoma at Retroperitoneal Region with Intra-thoracic Extension & Misdiagnosed as Lower Respiratory Tract Infection: A Case Report

Introduction: We are reporting a case of 18 year old boy who presented with features of lower respiratory tract infections and labelled as suffering from left suprarenal gland tumor. However, after complete evaluation, it is diagnosed as left retroperitoneal tumor extending into left thoracic cavity with involvement of left lower lobe lung. He underwent debulking surgery. Rhabdomyosarcoma (RMS ) originates from immature striated muscle and it is considered as the most aggressive malignant mesenchymal tumor. The most common location of RMS is head and neck region. The retroperitoneal presentation of embryonal RMS is extremely rare. The four histological features of RMS, classified by WHO are embryonal, alveolar, pleomorphic and spindle cell or sclerosing. Pleomorphic RMS has worse prognosis. The incidence of embryonal tumors is higher in males with bimodal age distribution, between 2-6 years and second peak between 10-18 years. Their detection is incidental when the size is small and as the size enlarges, symptoms helps in detection. Due to its rarity at retroperitoneal location, there is a lack of literature over the adjuvant treatment. As the size enlarges at retroperitoneal region, enblock resection with clear margins becomes a difficult task and if planned for R0 resection, multiorgan resection escalates surgical morbidity rate. Conclusion: It is a rare location of embryonal rhabdomyosarcoma at retroperitoneal region with rare presentation of intra-thoracic infiltration. R0 resection is the principle goal of surgical excision of retroperitoneal sarcoma.

Metastatic rhabdomyosarcoma of breast: A rare presentation

Rhabdomyosarcoma (RMS) is the most common pediatric soft-tissue sarcoma with head and neck as the preferred site followed by the genitourinary system in 13–17 years. It can involve the breast as either primary or secondary. A multidisciplinary treatment approach of chemotherapy or radiotherapy or mastectomy depends on the clinical profile of the patient. Embryonal RMS has a better prognosis than alveolar and pleomorphic subtypes. Here, we report the case of a 17-year-old girl who is a known case of primary embryonal RMS of the right maxillary antrum diagnosed 2 years back and administered neoadjuvant chemotherapy followed by radiotherapy-concurrent chemoradiotherapy. Later, she developed right breast lump, which on fine-needle aspiration cytology (FNAC) of the lump showed characteristic features of metastatic RMS, thus avoided surgical intervention of lumpectomy or mastectomy. The patient received adjuvant chemotherapy followed by radiotherapy and is doing well. The aim of the present case is to assess the safer, faster role of FNAC in the diagnosis of breast RMS. It is also recommended to include ultrasound/mammography of the breast as a protocol in the metastatic workup of RMS for adolescent females.

Multimodality imaging of adult rhabdomyosarcoma: the added value of hybrid imaging.

Rhabdomyosarcoma (RMS) represents more than 50% of paediatric soft tissue tumours. Conversely, it is extremely rare among adults, where it shows peculiar biological and clinical features that are still poorly investigated. RMS patients should be referred to a Sarcoma Centre, where the contribution of experienced radiologists plays a relevant role in the diagnostic assessment of the disease, including precise localisation, staging, image-guided biopsy, response evaluation after treatment and follow-up. Besides CT and MRI, hybrid imaging including positron emission tomography (PET)/CT and PET/MRI are giving an increasing contribution to provide functional insights about tumour biology and to improve the diagnostic accuracy of the imaging work-up. This review paper provides a revision of the pathology, clinical and radiological features of adult RMS, with a particular focus on the growing role of hybrid PET-based imaging.

Outcome of paediatric rhabdomyosarcoma attended in a tertiary care hospital, Dhaka, Bangladesh

Background: Rhabdomyosarcoma (RMS) is a malignant tumor of mesenchymal origin, is the most common form of paediatric soft tissue sarcoma. It is the third most common solid tumor comprising 4.5% of all childhood cancer with an annual incidence of 4.5 cases per million children. There is so no statistical data on RMS in Bangladesh because no study has done in Bangladesh.
 Objective: To evaluate the clinical characteristics and treatment outcome of children with rhabdomyosarcoma among tertiary care.
 Methods: A retrospective study carried out analysing the medical records of 39 patients with rhabdomyosarcoma from the BSMMU tumor registry. Medical records of children with rhabdomyosarcoma were reviewed over a period of 6 years from June 2011 to May 2017. Most patients received multimodality therapy (chemotherapy, surgery, radiotherapy).
 Results: The male female was ratio 1.2:1. More than half of cases presented with a mass at varying sites The predominant complaint 12.0% was pain. The primary site of disease was the head and neck in 46.0% followed by pelvis 40.0%. Pathologically most frequent histological subtype was in 46.0% embryonal rhabdomyosarcoma followed by alveolar rhabdomyosarcoma 23.0%, botryoid type 5.0%, spindle cell type 5.0% and unspecified 21.0%. At the time of diagnosis 64.0% of patients were TNM stage 3 next frequency is stage IV 23.0%. The survival rate from diagnosis to subsequent demise was poor – between 13 days and 3.5 years. The overall 5-year survival rate was 41.0% which is may be due to advanced stage of disease.
 Conclusion: The majority of presentations were in the advanced stages of disease but sensitive to multimodality therapy. Poor survival rate is correlated with the advanced stage of the disease. The clinical characteristics of rhabdomyosarcoma at BSMMU Hospital are similar to worldwide countries, but not like developed countries. Further multicentre studies are needed to report our experiences with rhabdomyosarcoma.
 Bangladesh Med Res Counc Bull 2020; 46(1): 17-21

Bilateral Anterior Uveitis in a Northern Saw-whet Owl (Aegolius acadicus) With a Metastatic Pectoral Malignant Mesenchymoma

A captive, adult, male northern saw-whet owl (Aegolius acadicus) was examined for blepharospasm of the left eye. The owl was diagnosed with bilateral anterior uveitis and a corneal ulceration in the left eye. It was treated with oral and topical nonsteroidal anti-inflammatory medications and a topical antibiotic. Multiple recheck examinations and medication adjustments were performed over the next 4 months, at the end of which time the bilateral anterior uveitis was controlled with a topical nonsteroidal anti-inflammatory applied 3 times per week to both eyes. The owl was re-examined 2 months later after 2 suspected neurologic episodes. On physical examination, the owl was quiet and had difficulty standing and ambulating. Five firm multilobular and immobile masses were identified overlying the pectoral muscle and sternum. Fine-needle aspiration from 1 mass revealed neoplastic cells consistent with a sarcoma. The owl was euthanatized. On the basis of results of histopathologic examination, the mass was diagnosed as a pleomorphic spindle cell sarcoma with features of rhabdomyosarcoma, liposarcoma, and osteosarcoma. Numerous tumor cells were immunopositive for myoglobin and desmin, indicating striated muscle origin. Although a metastatic lesion was present in 1 adrenal gland, lesions of inflammation or neoplasia were absent in either eye on histopathologic examination. This report describes an apparent ocular manifestation of systemic disease in an avian species with clinically diagnosed recurrent anterior uveitis.

Clinical and Cytogenetic Profiles of Rhabdomyosarcoma with Bone Marrow Involvement in Korean Children: A 15-Year Single-Institution Experience.

BackgroundRhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Alveolar RMS (ARMS) is characterized by FOXO1-related chromosomal translocations that result in a poorer clinical outcome compared with embryonal RMS (ERMS). Because the chromosomal features of RMS have not been comprehensively defined, we analyzed the clinical and laboratory data of childhood RMS patients and determined the clinical significance of chromosomal abnormalities in the bone marrow.MethodsFifty-one Korean patients with RMS <18 years of age treated between 2001 and 2015 were enrolled in this study. Clinical factors, bone marrow and cytogenetic results, and overall survival (OS) were analyzed.ResultsIn total, 36 patients (70.6%) had ERMS and 15 (29.4%) had ARMS; 80% of the ARMS patients had stage IV disease. The incidences of bone and bone marrow metastases were 21.6% and 19.6%, respectively, and these results were higher than previously reported results. Of the 40 patients who underwent bone marrow cytogenetic investigation, five patients had chromosomal abnormalities associated with the 13q14 rearrangement. Patients with a chromosomal abnormality (15 vs 61 months, P=0.037) and bone marrow involvement (17 vs 61 months, P=0.033) had a significantly shorter median OS than those without such characteristics. Two novel rearrangements associated with the 13q14 locus were detected. One patient with concomitant MYCN amplification and PAX3/FOXO1 fusion showed an aggressive clinical course.ConclusionsA comprehensive approach involving conventional cytogenetics and FOXO1 FISH of the bone marrow is needed to assess high-risk ARMS patients and identify novel cytogenetic findings.

Embryonal Rhabdomyosarcoma of the Cervix in Young Women.

Cervical rhabdomyosarcoma (RMS) is an extremely rare disease, and there is no precise criteria related to its treatment. Our aim was to describe the clinical and pathological features of cervical RMS. Clinicopathological data of cases with cervical RMS were retrieved from the computerized database of Etlik Zubeyde Hanim Women's Health and Research Hospital. Five patients with the diagnosis of cervical RMS who underwent surgical treatment and had adjuvant chemotherapy between 2003 and 2015 were included in the study. Mean age of patients at the time of diagnosis was 15.8 ± 2 years. Abnormal vaginal bleeding and mass were the most common complaints. All patients had embryonal rhabdomyosarcoma (E-RMS) and Group I disease according to the Intergroup Rhabdomyosarcoma Study Group clinical classification system. Cone biopsy and polypectomy were performed in four patients, and radical abdominal hysterectomy with pelvic-paraaortic lymphadenectomy was performed in one patient. Chemotherapy consisting vincristine, dactinomycin, and cyclophosphamide was given as an adjuvant therapy. Estimated 5-year overall survival and disease-free survival were 40% and 37.5%, respectively. We report a small series of patients with cervical E-RMS who were treated with surgery and adjuvant chemotherapy. Although all patients in the present study had good prognostic factors, survival was not as good as indicated in the literature. Diminished survival of our patient group may be associated with underlying molecular and pathophysiologic differences other than stage and histological subtype that have not been discovered yet.

Pleomorphic Rhabdomyosarcoma in upper limb in an adult

Rhabdomyosarcoma (RMS) is the most common form of soft tissue sarcoma in the first 2 decades of life, with a peak age incidence in very young children. Due to the rarity of adult RMS, information regarding its clinical and biologic characteristics is very limited. We report a case of pleomorphic RMS of upper extremity in a 50-year-old man. There was no metastasis of the tumor. The patient underwent surgery with enbloc excision of the tumor. Histopathological examination showed typical features of pleomorphic RMS composed of large polygonal pleomorphic cells with eosinophilic cytoplasm and plenty of large multinucleated tumor giant cells having bizarre nuclei. Postoperatively patient took radiotherapy. There was no recurrence of tumor with follow-up of 2 years.

Activation of the hedgehog pathway confers a poor prognosis in embryonal and fusion gene-negative alveolar rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and comprises two major histological subtypes: alveolar rhabdomyosarcoma (ARMS) and embryonal rhabdomyosarcoma (ERMS). Seventy-five percent of ARMS harbor reciprocal chromosomal translocations leading to fusion genes of the forkhead transcription factor FOXO1 and PAX3 or PAX7. The hedgehog (Hh) pathway has been implied in tumor formation and progression of various cancers including RMS. However, whether Hh pathway activation presents a general feature of RMS or whether it is restricted to specific subgroups has not yet been addressed. Here, we report that marker genes of active Hh signaling, that is, Patched1 (Ptch1), Gli1, Gli3 and Myf5, are expressed at significantly higher levels in ERMS and fusion gene-negative ARMS compared with fusion gene-positive ARMS in two distinct cohorts of RMS patients. Consistently, Gli1 expression correlates with Ptch1 expression in ERMS and fusion gene-negative ARMS, but not in fusion gene-positive ARMS. In addition, expression levels of MyoD1 are significantly lower in ERMS and fusion gene-negative ARMS, pointing to an inverse association of Hh activation and early muscle differentiation. Moreover, Myf5 is identified as a novel excellent class predictor for RMS by receiver operating characteristic analysis. Importantly, high expression of Ptch1 or low MyoD1 expression significantly correlate with reduced cumulative survival in fusion gene-negative RMS underscoring the clinical relevance of these findings. By showing that Hh signaling is preferentially activated in specific subgroups of RMS, our study has important implications for molecular targeted therapies, such as small molecule Hh inhibitors, in RMS.

Pediatric rhabdomyosarcoma in Morocco

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the first two decades of life. There is, however, a paucity of reports on the pattern of its occurrence in Africa. This study analyses the epidemiological pattern, clinical features, histology, and outcome in Moroccan children presenting with RMS. We retrospectively studied 100 consecutive cases of histologically proven RMS in previously untreated children <15 years old followed at the Pediatric Oncology Unit of the Children's Hospital of Rabat from January 1995 to December 2004. RMS represented 5% of all the patients treated for cancer during this period. The male/female ratio was 2:1 with a mean age at diagnosis of 5 years. The embryonal subtype was the most frequent (73%) and the head and neck was the most common site of disease, followed by the genito-urinary tract and limbs. Chemotherapy was used in all patients; 44% also had a radical surgery and 23% radiation therapy. The event-free survival (EFS) at 10 years was 39% with relapse as the first cause of treatment failure. The overall survival at 10 years was 70%. The rate of treatment abandonment was 37%. Epidemiology and clinical features of RMS in Moroccan children does not differ from others countries. However, EFS is lower than that reported elsewhere due to occasional lack of availability of drugs, inadequate local control, and abandonment.

On the histological features of rhabdomyosarcoma

On the histological features of rhabdomyosarcoma

Hypoxia-Inducible Factor-Dependent Degeneration, Failure, and Malignant Transformation of the Heart in the Absence of the von Hippel-Lindau Protein

Hypoxia-inducible transcription factor 1 (HIF-1) and HIF-2alpha regulate the expression of an expansive array of genes associated with cellular responses to hypoxia. Although HIF-regulated genes mediate crucial beneficial short-term biological adaptations, we hypothesized that chronic activation of the HIF pathway in cardiac muscle, as occurs in advanced ischemic heart disease, is detrimental. We generated mice with cardiac myocyte-specific deletion of the von Hippel-Lindau protein (VHL), an essential component of an E3 ubiquitin ligase responsible for suppressing HIF levels during normoxia. These mice were born at expected frequency and thrived until after 3 months postbirth, when they developed severe progressive heart failure and premature death. VHL-null hearts developed lipid accumulation, myofibril rarefaction, altered nuclear morphology, myocyte loss, and fibrosis, features seen for various forms of human heart failure. Further, nearly 50% of VHL(-/-) hearts developed malignant cardiac tumors with features of rhabdomyosarcoma and the capacity to metastasize. As compelling evidence for the mechanistic contribution of HIF-1alpha, the concomitant deletion of VHL and HIF-1alpha in the heart prevented this phenotype and restored normal longevity. These findings strongly suggest that chronic activation of the HIF pathway in ischemic hearts is maladaptive and contributes to cardiac degeneration and progression to heart failure.

Clinicopathologic Features of Rhabdomyosarcoma of Gynecologic Origin in Adults

Clinicopathologic Features of Rhabdomyosarcoma of Gynecologic Origin in Adults

Soft-tissue sarcomas of the extremities in patients of pediatric age

The extremity site is a peculiar location for soft-tissue sarcomas (STS) of children and adolescents. Here we report the experience of the Pediatric Oncology Unit of the Istituto Nazionale Tumori of Milan, Italy, concerning 204 patients with STS of the limbs treated between 1977 and 2006. The study series included 52 patients with rhabdomyosarcoma (RMS)(65% of which were of the alveolar subtype), nine with extraosseous Ewing sarcoma and 143 with non-rhabdomyosarcoma soft-tissue sarcomas (NRSTS), 38% of which were synovial sarcoma. Patients were treated with a multimodality approach including surgery, chemotherapy, and radiotherapy. For the RMS patients, the 5-year event-free survival (EFS) rate was 37.1%, with distant metastases being the main cause of treatment failure. The outcome was particularly poor for patients with large invasive tumors, hand/foot involvement and/or nodal or distant metastases, and for patients who were not given radiotherapy. For the extraosseous Ewing sarcoma cases, 5-year EFS was 74%. For the NRSTS cases, the 5-year EFS was 72.6%: tumor size and local invasiveness, tumor grade, malignant peripheral nerve sheath tumor (MPNST) histology, and distant metastases were the main prognostic factors. While the limbs are the most common sites of NRSTS and are often characterized by a more favorable prognosis than for axial tumors, the clinical features of extremity RMS often differ from those of RMS of other sites, with a higher incidence of unfavorable prognostic factors (e.g., alveolar subtype) and consequently unsatisfactory treatment results. The treatment of these patients is complex and necessarily multidisciplinary, and it demands not only adequate experience of treating children and adolescents in clinical trials, but also particular skills in the field of orthopedic surgery.

Clinicopathologic Features of Rhabdomyosarcoma of Gynecologic Origin in Adults

Rhabdomyosarcoma (RMS) is the most common soft tissue tumor found in children. Up to 20% of RMS tumors in children originate in the genital tract making this the second most common site. RMS of gynecologic origin in adults is much less common. The purpose of this study was to describe the clinical and pathologic features of RMS of the adult female genital tract. We reviewed the histologic slides of women 16 years of age and older and included them in our study if they contained the classic histologic features of RMS as described by the 2002 World Health Organization classification of tumors. Rhabdomyoblastic components present in other established malignancies were not studied. We identified 15 patients, with a median age of 48 years (range, 16 to 69). Eleven (73%) of the tumors were of embryonal histology (cervix, 8; uterus, 2; and ovary, 1). Of the remaining 4 tumors, 2 were of alveolar (vulva) and 2 of pleomorphic (uterus, 1; fallopian tube, 1) histologic subtype. The majority (79%) of these patients presented with locoregional disease and had surgery as their primary intervention (73%). The median progression-free survival (PFS) and disease-specific survival was 9 months [95% confidence interval (CI), 1-24] and 21 months (95% CI, 14-28), respectively. The 5-year disease-specific survival was only 29%. There was a significant difference in PFS between cases of embryonal compared to cases with nonembryonal histology (19 vs. 3 mo, respectively) (P=0.04). Adult RMS of gynecologic origin presents with locoregional disease and most are morphologically similar to pediatric RMS; however, adult RMS behaves more aggressively, with worse overall survival. It is unclear whether these divergent outcomes are the result of differences in clinical management or because these tumors are biologically distinct.

Composite Extrarenal Rhabdoid Tumor of the Skin: Cytology, Morphology, Electron Microscopy and Special Stain Findings

We present the findings of a rare and very aggressive primary skin tumor, composite extrarenal rhabdoid tumor (CERT) with features of rhabdomyosarcoma. Clinical history: A 53‐year‐old woman presented with a 2.5 cm ulcerated nodule on her right medial calf. On exam, she also exhibited inguinal lymphadenopathy. Pathology: Fine needle aspiration of a lymph node and punch biopsy of the skin nodule disclosed an epithelioid cell morphology with rhabdoid cells, solid growth, and a high mitotic rate (&gt;70 figures/10 HPF). Upon wide excision of the tumor, electron microscopy (EM) and special stains were performed. Since the differential diagnosis was broad, a large number of stains were performed: tumor was positive for vimentin, desmin, muscle specific actin, WT‐1, CD56, and CD10, and negative for S‐100, melan A, cytokeratins, EMA, CD34, fast myosin, myoglobin, myogenin, myoD1, smooth muscle actin, and NSE. EM revealed rhabdoid cells with perinuclear globules of intermediate filaments corresponding to the positive desmin stain. Summary: The patient was treated with chemotherapy without regression of presumed lung metastases. The CERT is a rare, aggressive tumor that extraordinarily presents as a primary skin tumor. The differential is broad and nomenclature confusing. Extensive ancillary pathology studies are required for appropriate diagnosis.

Primary osteochondrorhabdomyosarcoma (malignant mesenchymoma) of the fibula: a rare tumour in an unusual site - Case report and review of the literature. Case report

Malignant mesenchymoma, defined by Stout as sarcomas comprising two or more unrelated differentiated tissue elements other than a fibrosarcoma component, is rare. We report a case of primary malignant mesenchymoma of the proximal fibula in a 10-year-old female student who presented with pain and swelling of the right knee for 2 months. Initial biopsy showed features of rhabdomyosarcoma only, but the resected specimen revealed additional osteosarcomatous and chondrosarcomatous elements. The patient remained well more than 5 years after initial presentation. Including our present patient, 16 cases of primary malignant mesenchymoma of bone are found in the English literature, affecting mainly adolescents and young adults, with a slight male predominance and predilection for the metaphysis of long bones, especially around the knee. More than 60% of the patients develop metastasis, almost invariably to the lung, but occasionally to the brain. About 60% of the patients, all with metastasis, died mostly within one year of diagnosis. The clinical features of primary malignant mesenchymoma of bone thus resemble those of conventional osteosarcoma. Moreover, our case illustrates that, with combination chemotherapy targeted for individual elements, the prognosis of this rare tumour might be much improved, as in osteosarcoma.