Spindle cell rhabdomyosarcoma: a brief diagnostic review and differential diagnosis

Giant spindle cell rhabdomyosarcoma in an adult thorax: A case report

Spindle cell rhabdomyosarcoma (SCRM), a rare and distinct subtype of RM, predominantly affects children. While SCRM can manifest in the head and neck regions of adults, primary occurrences in the thorax are exceedingly uncommon. In the present study, a 24-year-old female patient was admitted to the Affiliated Hospital of Zunyi Medical University (Zunyi, China) with a 10-month history of dull pain in the right side of the chest. The patient had previously received treatment for right-sided tuberculous pleurisy at another hospital for 6 months, but the symptoms persisted, and the chest pain progressively worsened. A chest computed tomography scan now revealed a large mass in the right thorax. Pathological examination following surgical resection confirmed a diagnosis of SCRM. The patient did not undergo standardized postoperative chemoradiotherapy and the 5-year follow-up examination indicated tumor recurrence. Primary thoracic SCRM is a rare tumor that morphologically resembles other spindle cell tumors. Immunohistochemistry is crucial for an accurate diagnosis, and surgical resection remains the primary treatment approach. The clinicopathological features, molecular genetic characteristics and biological behavior of SCRM are largely unknown due to its rarity. Consequently, large-sample studies are essential to enhance the understanding of this tumor and advance precision medicine treatments.

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.

Small biopsies in the head and neck: Bone and soft tissue

Bone and soft tissue lesions in the head and neck encompass not only a broad morphologic spectrum but also significant inherent clinicopathologic overlap. Epidemiology, radiology, and location - similar to the diagnostic assessment in other sites - are especially important considerations in the context of an established mesenchymal proliferation. Herein, the approach towards diagnosis is stratified by morphology (spindle, sarcomatoid, epithelioid, round cell), cellular lineage (fibroblastic, nerve sheath, rhabdomyogenic), and tumor grade (benign, low- to high-grade malignant) as the basis of further immunohistochemical or molecular investigation.

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.

A case report of primary para-testicular spindle cell rhabdomyosarcoma

Para-testicular rhabdomyosarcoma (PTRMS) is a rare tumor, and it accounts for 7% of all rhabdomyosarcoma tumors. Among all the rhabdomyosarcoma (RMS) types, the spindle cell RMS is extremely rare. The present study describes a case of a para-testicular spindle cell RMS that was treated with a radical inguinal orchiectomy (RIO) and right scrotal resection. A 17-year-old male patient presented with a half-year history of a rapidly growing, painless, right scrotal mass. His CT of the pelvic cavity showed a mixed-density mass in the right scrotum, and the maximum cross-sectional area was approximately 76.5 mm × 64.5 mm. An X-ray of the chest demonstrated no evidence of metastasis, and a local surgical excision was performed subsequently. The histopathological and immunohistochemical examination confirmed the final diagnosis of spindle cell RMS. As a newly diagnosed case, strict and regular follow-up is needed. This article focuses on the importance of prompt recognition, diagnosis, pathological features, and appropriate management of para-testicular spindle cell RMS.

A report of a rare case of paratesticular spindle cell rhabdomyosarcoma in an adult patient

Paratesticular embryonal rhabdomyosarcoma is a rare malignancy developed from a mesenchymal tissue of spermatic cord, testicular components. Spindle cell rhabdomyosarcoma (SCR) is a variant of embryonal rhabdomyosarcoma affecting the paratesticular region of adult patients and is even rarer. Given the limited guidelines available to manage SCR and the rarity of reported cases, our report aims to discuss a new case of this entity in a 66-years old Moroccan patient. Paratesticular SCR is a very rare tumor and requires attention from urologists to consider this entity as differential diagnosis when suspecting malignancies in the urogenital region.

Invasive spindle-cell rhabdomyosarcoma with osteolysis in a dog: case report and literature review

Rhabdomyosarcoma (RMS), a malignant mesenchymal neoplasm derived from skeletal muscle, is relatively rare in both human and veterinary medicine. Here we report an unusual case of invasive spindle-cell RMS (SCRMS) with bone infiltration and pathologic fracture in a 3.5-y-old intact female Bulldog. Radiographically, a large, predominantly osteolytic mass in the tibia and fibula of the left hindlimb had features typical of a malignant primary bone tumor. Clinically, osteosarcoma was suspected, and the leg was amputated. Histologically, the mass was composed of loosely interwoven spindle-cell fascicles; tumor cells were fusiform with cigar-shaped nuclei and abundant eosinophilic cytoplasm. The neoplastic cells were strongly immunopositive for vimentin, muscle-specific actin, desmin, myogenin, and myoD1. Invasive SCRMS with osteolysis was diagnosed based on the histologic examination and immunohistochemical (IHC) stains. The dog was alive without any evidence of local recurrence or distant metastasis 18 mo post-surgery. RMS should be included in the differential diagnosis when osteolysis occurs; IHC staining confirmation is of great value for definitive diagnosis and treatment planning.

Retroperitoneal Spindle Cell Rhabdomyosarcoma With Compression Features in a 48-Year-Old Male: A Case Report

Spindle cell rhabdomyosarcoma (SC-RMS) is an unprecedented version of embryonal rhabdomyosarcomas (RMSs) that emerges from the mesenchyme with the capacity to differentiate into skeletal muscle cells. Retroperitoneal RMS is extremely rare in the adult population. We present the case of a primary spindle cell retroperitoneal RMS with compression features. Investigation-based diagnosis of RMS is difficult due to the lack of specificity of clinical findings. Radiology does not help in making an accurate diagnosis. Surgical removal of the tumor followed by chemotherapy and radiotherapy is the best possible treatment for RMS in adults. SC-RMS has a poor long-term prognosis. To our knowledge, such cases of retroperitoneal SC-RMS compressing the abdominal viscera and resulting in hydroureteronephrosis have never been reported before.

Spindle cell rhabdomyosarcoma in the adult: A rare case report

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

Recurrent Giant Cell Fibroblastoma in an Infant: A Diagnostic Challenge

Background: Giant cell fibroblastoma (GCF) shows a wide spectrum of morphological patterns which may lead to a misdiagnosis of sarcoma. Case Report: This 14- month- old baby was referred to us for recurrent left scrotal embryonal rhabdomyosarcoma (ERMS), first diagnosed at 8 months, status post chemotherapy. Review of previous histology, cytology (with frequent multinucleated floret type giant cells but without cross striations) and immunohistochemistry resulted in the change of diagnosis to GCF. It was re-excised, recurred at 20 months of age, and was again re-excised. The morphology was the same in both recurrences as the original. Conclusion: Despite chemotherapy, the histology of multiple recurrences for GCF remained the same as the original. Cytologically, identification of the multinucleated floret like giant cells without cross striations was helpful in differentiating this lesion from embryonal rhabdomyosarcoma.

Tongue Spindle Cell Rhabdomyosarcoma: A Rare Case Report and Literature Review

Rhabdomyosarcoma (RMS) is a malignant soft tissue neoplasm with its origin in the skeletal muscle and is extremely rare in adults. By the World Health Organization (WHO), a new variant of RMS has been classified, i.e. the spindle cell (Sc) and sclerosing (S) RMS. While the Sc-RMS shows intersecting fascicles of nonpleomorphic spindle cells, the S-RMS is characterized by a marked hyalinization in a pseudovascular growth pattern associated with round-to-spindled tumour cells. According to the analysed data, the Sc/S-RMS variant has a worse outcome than other variants. The new classification of the Sc/S-RMS variant is valuable to the clinical practice. There are not many oral Sc/S-RMS cases reported. The aim of this paper is to demonstrate that an early diagnosis, an adequate treatment and a multidisciplinary approach have a positive effect on the prognosis of the patient. In this study, we analyse a new case of Sc-RMS variant in a young adult with an early diagnosis and a favourable outcome as a result of an appropriated multidisciplinary treatment: early surgery, radiotherapy and chemotherapy treatment.

Rare Variant of Adult Rhabdomyosarcoma Presenting as a Palatal Swelling

A 26-year-old male was referred to the Department of Oral and Maxillofacial Surgery of a tertiary care hospital in Lahore with chief complaint of painless swelling on the right palate of 40 days duration. Clinical differential diagnosis included squamous cell carcinoma, Ewing sarcoma, fibrosarcoma, neuroblastoma and rhabdomyosarcoma. Computed tomography scan revealed hypodense mass with necrotic changes. Histological examination of the excised tumor revealed malignant neoplasm arranged in fascicles and bundles comprising of spindle cells with pleomorphic, hyperchromatic nuclei and increased atypical mitosis. Immunohistochemical analysis showed negative staining with Cytokeratin, S100, CD34, Stat6, h-Caldesmon and EMA while the tumour cells were positive for desmin, myogenin, smooth muscle actin, CD-99 and MyoD1 thus confirming the diagnosis of spindle cell rhabdomyosarcoma.

Testicular Torsion in a Rare Case of Prostatic Spindle Cell Rhabdomyosarcoma

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

Cervical Infantile Fibrosarcoma: a rare cause of paediatric parapharyngeal neck mass

Soft tissue tumors are not uncommon in childhood and comprise entities that range from common to very rare malignancies. Infantile fibrosarcoma (IFS) is a rare pediatric malignancy mainly seen in the first two years of life. The data about the incidence of infantile fibrosarcoma occurring in the neck in the Indian subcontinent is scarce. To the best of our knowledge, only one case of infant cervical IFS has been reported previously in the Indian subcontinent. We present another case of an eight-year-old male patient with a rapidly growing mass on the left side of the neck. He was successfully treated with a combined modality of surgery and chemotherapy with a good outcome. Among the soft tissue tumors of childhood, IFS is a rare entity. It has a good prognosis and lesser chance of distant metastasis as compared to adult fibrosarcoma. Though surgical excision is the mainstay of treatment, chemotherapy also has a significant role in the treatment of primary tumor and metastasis. We discuss the stated case to bring to the notice this uncommon cause, which can be considered as a differential diagnosis of upper cervical swellings. A better understanding of this entity would help in early diagnosis and aggressive treatment, reducing the overall morbidity and mortality.

Nasal spindle cell tumor with rhabdomyoblastic features: A rare and diagnostically difficult case

Nasal spindle cell rhabdomyosarcoma is very rare. The tumor is sometimes confused with other spindle cell tumors. We herein report a case of nasal spindle cell tumor in a 62-year-old woman. The patient first presented herself to a medical doctor’s office after an episode of left epistaxis. An intranasal tumor was found and resected. The tumor was composed of spindle cells, and she was diagnosed with desmoid-type fibromatosis. Five years after the initial episode, an intranasal tumor was found again. The tumor showed a fascicular growth pattern with high cellularity and was predominantly composed of spindle cells. Scattered eosinophilic rhabdomyoblasts were also observed. She was diagnosed with spindle cell rhabdomyosarcoma. This is a unique case report not only because nasal spindle cell rhabdomyosarcoma is very rare but also because the tumor was initially diagnosed as desmoid-type fibromatosis. It is important to consider spindle cell rhabdomyosarcoma as a differential diagnosis of nasal spindle cell tumors.

Case Report of a Local Recurrence of Spindle Cell Embryonal Rhabdomyosarcoma

INTRODUCTION

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and adolescents. Spindle cell RMS is a rare variant of embryonal RMS that has a predilection for young males.

AIM

We are presenting here a case of a local recurrence of an embryonal variant of the spindle cell RMS in a 19-year-old male.

CASE REPORT

In this report it is described the study of patient with local recurrence of spindle cell embryonal RMS of the left testis after left orchiectomy and adjuvant chemotherapy. Computed tomography of the abdomen was used to evaluate the tumor. The recurrent mass was about 7,5cm and the patient was operated and discharged after 6 days in a good condition. Six months after the operation the patient had a new recurrence of RMS in the left retroperitoneal space.

CONCLUSION

RMS is a malignant tumor of mesenchymal origin that is treated by a combination of surgery, chemotherapy, and radiation. However, up to one-third of patients experience recurrence.

Embryonal and Alveolar Rhabdomyosarcoma in Adults: Real-Life Data From a Tertiary Sarcoma Centre

AIMS

Embryonal and alveolar rhabdomyosarcoma (ERMS, ARMS) are subtypes of RMS that mainly occur in children, with relatively good outcomes. The incidence in adults is extremely low and survival is significantly worse compared with children. Data are scarce and literature generally combines all RMS subtypes, including pleomorphic RMS, which primarily occurs in adults and behaves more like undifferentiated pleomorphic sarcoma. The aim of this study was to evaluate patient and tumour characteristics, outcome and prognostic factors in adult patients with ERMS and ARMS.

MATERIALS AND METHODS

All adult (18 years or older) ERMS and ARMS patients (presenting 1990-2016) were identified from a prospectively maintained database and were included in this analysis.

RESULTS

Overall, 66 patients were included (42 men, 24 women). The median age at presentation was 28 years (range 18-71). The median overall survival for all ARMS (n = 42) and ERMS (n = 24) patients was 18 months, with a 5-year overall survival rate of 27%. Patients presenting with localised disease (n = 38, 58%) and metastatic disease (n = 25, 42%), had a 5-year overall survival rate of 36% and 11%, respectively. In univariate analysis we found alveolar subtype, fusion gene positivity, infiltrative tumour and metastatic presentation to be negative prognostic factors.

CONCLUSION

Survival in adult ERMS and ARMS patients is poor and the current data may be useful in the design of trials with novel agents. Ideally, paediatric and adult oncologists should set up trials together to get a better understanding of biological, genetic and clinically relevant factors in this disease.

Fibroblastic and myofibroblastic tumors of children: new genetic entities and new ancillary testing

Fibroblastic and myofibroblastic tumors comprise a morphologically diverse and biologically variable group of neoplasms that affect a wide age range. Specific entities tend to occur most frequently in infants and young children. Recent years have witnessed a proliferation of information concerning the unique biology of these tumors. In this report, I will review recent findings that serve to further characterize this group of neoplasms. Included will be newer information on fibrous hamartoma of infancy, infantile myofibromatosis, lipofibromatosis, and infantile fibrosarcoma and tumors resembling it, including primitive myxoid mesenchymal tumor of infancy and new genetic entities. I will also discuss the differential diagnosis, which includes spindle cell rhabdomyosarcoma, dermatofibrosarcoma protuberans, and calcifying aponeurotic fibroma.

Combined Sclerosing and Spindle Cell Rhabdomyosarcoma in Previous Craniotomy Site: A Case Report and a Review of the Literature

Sclerosing rhabdomyosarcoma (RMS) is a rare subtype of RMS with unique prominent stromal hyalinization and a pseudovascular architecture. It overlaps morphologically with spindle cell RMS and poses both diagnostic and therapeutic challenges because of its rarity and aggressive clinical course. In this article, we report a case of sclerosing RMS arising from a prior craniotomy site, which demonstrated both sclerosing and spindle cell components. A literature review of RMS with sclerosing morphology identified 122 cases. Our review documents the following: sclerosing RMS occurs in both childhood and adult populations, has a predilection for the head and neck areas, and has a worse prognosis in adults. Sclerosing RMS harbors a high frequency of MYOD1 mutations, conferring a poor clinical outcome. Sclerosing RMS and spindle RMS likely represent a morphologic spectrum of one entity.

Current diagnostics and treatment of fibrosarcoma -perspectives for future therapeutic targets and strategies

Adult-type fibrosarcoma is a rare and highly aggressive subtype of soft tissue sarcomas. Due to the existence of other spindle-cell shaped sarcomas, its diagnosis is always one of exclusion. The likelihood of misdiagnoses between similar tumour entities is high, and often leads to inappropriate tumour treatment. We summarize here the main features of fibrosarcoma. When fibrosarcoma is appropriately diagnosed, the patient`s overall prognosis is generally quite poor. Fibrosarcoma is characterized by its low sensitivity towards radio- and chemotherapy as well as by its high rate of tumour recurrences. Thus it is important to identify new methods to improve treatment of this tumour entity. We discuss some promising new directions in fibrosarcoma research, specifically focusing on more effective targeting of the tumour microenvironment. Communication between tumour cells and their surrounding stromal tissue play a crucial role in cancer progression, invasion, metastasis and chemosensitivity. The therapeutic potential of targeting the tumour microenvironment is addressed.

PAX7 Expression in Rhabdomyosarcoma, Related Soft Tissue Tumors, and Small Round Blue Cell Neoplasms

Rhabdomyosarcoma, the most common soft tissue malignancy of childhood, is a morphologically variable tumor defined by its phenotype of skeletal muscle differentiation. The diagnosis of rhabdomyosarcoma often relies in part on the identification of myogenic gene expression using immunohistochemical or molecular techniques. However, these techniques show imperfect sensitivity and specificity, particularly in scant tissue biopsies. Here, we expand the toolkit for rhabdomyosarcoma diagnosis by studying the expression of PAX7, a transcriptional regulator of mammalian muscle progenitor cells implicated in the pathogenesis of rhabdomyosarcoma. Immunohistochemical analysis of tissue microarrays using a monoclonal anti-PAX7 antibody was used to characterize PAX7 expression in 25 non-neoplastic tissues, 109 rhabdomyosarcomas, and 697 small round blue cell or other soft tissue tumors. Among non-neoplastic tissues, PAX7 was specifically expressed in adult muscle progenitor cells (satellite cells). In embryonal rhabdomyosarcoma, PAX7 expression was positive in 52 of 63 cases (83%), negative in 9 of 63 cases (14%), and focal in 2 of 63 cases (3%). PAX7-positive embryonal rhabdomyosarcoma cases included several showing focal or negative myogenin expression. PAX7 expression in alveolar rhabdomyosarcoma was positive in 6 of 31 cases (19%), negative in 14 of 31 cases (45%), and focal in 11 of 31 cases (36%). In addition, PAX7 was expressed in 5 of 7 pleomorphic rhabdomyosarcomas (71%) and 6 of 8 spindle cell rhabdomyosarcomas (75%). Among histologic mimics, only Ewing sarcoma showed PAX7 expression (7/7 cases, 100%). In contrast, expression of PAX7 was not seen in the large majority (688/690, 99.7%) of examined cases of other soft tissue tumors, small round blue cell neoplasms, and leukemias/lymphomas. In summary, immunohistochemical analysis of PAX7 expression may be a useful diagnostic tool in the assessment of skeletal muscle differentiation in human tumors.

Rhabdomyosarcoma, Spindle Cell/Sclerosing Variant: A Clinical and Histopathological Examination of this Rare Variant with Three New Cases from the Oral Cavity

Spindle cell/sclerosing rhabdomyosarcoma (S-ScRMS) was recently recognized in 2013 by the World Health Organization (WHO) as a stand-alone entity (Parham et al., WHO classification of tumours of soft tissue and bone, IARC Press, Lyon, 2013). Historically, the spindle cell and sclerosing variants were subcategorized under embryonal type rhabdomyosarcoma. Current data supports that certain S-ScRMS cases have a more aggressive clinical course with reduction of long-term survival, and those found in the head and neck region often exhibit extensive local recurrence. Furthermore, due to variable histopathologic appearances and immunohistochemical findings, misdiagnosis is common. We aim to report the variability in histopathologic patterns, immunohistochemical findings, radiographic features, and clinical data on three new cases of S-ScRMS presenting in the oral cavity of young adult males (ages 22, 24, and 39 years). The English-language literature on S-ScRMS is briefly reviewed as well.

Spindle-cell rhabdomyosarcoma of the thumb: Rare site, rare tumor in a child

Spindle-cell rhabdomyosarcoma (RMS) is a relatively recently recognized favorable variant of embryonal RMS occurring mainly in the paratesticular and head and neck regions. Cytological reports of spindle-cell RMS have been sparse in the literature and the awareness of its cytological features is not very wide among cytopathologists. A 2-year-old girl was brought to clinical attention for a progressively enlarging swelling of right thumb. Imaging studies showed it to be a soft-tissue tumor in the subcutaneous region. Fine-needle aspiration yielded moderately cellular smears composed of small, round cells and few spindle cells with tapered cytoplasm. A cytological impression of RMS was rendered, which was later confirmed as spindle-cell RMS on excision biopsy. Spindle-cell RMS, a favorable prognostic variant of embryonal RMS, should be considered in the cytologic diagnosis of soft-tissue tumors with round cell and spindle cell morphology. This is especially true for tumors occurring in hitherto unreported sites. Diagn. Cytopathol. 2016;44:1094-1097. © 2016 Wiley Periodicals, Inc.

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.

Epididymal Inflammatory Pseudotumor With Downstream Sperm Granuloma in an Adolescent Patient: A Case Report and Review of the Literature

Herein we describe the first reported case of epididymal inflammatory pseudotumor (IPT) with incidental sperm granuloma in an adolescent. IPTs of epididymal origin are very rare, with a differential diagnosis including benign and malignant processes. Rhabdomyosarcomas and inflammatory myofibroblastic tumors are important diagnostic considerations that display pathologic similarities to IPTs. These lesions were excluded from diagnosis in this case and the important pathologic features allowing for exclusion are detailed within. Lastly, sperm granulomas are extremely rare pathologic findings in pediatric patients and their presence in this situation is likely the result of downstream tumor obstruction.

Novel PAX3-NCOA1 Fusions in Biphenotypic Sinonasal Sarcoma With Focal Rhabdomyoblastic Differentiation

Sarcomas arising in the sinonasal region are uncommon and encompass a wide variety of tumor types, including the newly described biphenotypic sinonasal sarcoma (BSNS), which is characterized by a monomorphic spindle cell proliferation with dual neural and myogenic phenotypes. Most BSNSs harbor a pathognomonic PAX3-MAML3 fusion driven by t(2;4)(q35;q31.1), whereas the alternative fusion partner gene remains unidentified in a subset of PAX3-rearranged cases. As NCOA1 on 2p23 is a known partner in PAX3-related fusions in other tumor types (ie, alveolar rhabdomyosarcoma), we investigated its status by fluorescence in situ hybridization (FISH) and reverse transcription polymerase chain reaction assays in 2 BSNS cases showing only PAX3 gene rearrangements. Novel PAX3-NCOA1 fusions were identified in these 2 index cases showing an inv(2)(q35p23) by FISH and confirmed by reverse transcription polymerase chain reaction. Five additional BSNS cases with typical morphology were studied by FISH, revealing a PAX3-MAML3 fusion in 4 cases and only PAX3 rearrangement in the remaining case without abnormalities in MAML3 or NCOA1 gene. Except for 1 case with surface ulceration, all other tumors lacked increased mitotic activity or necrosis, and all cases immunohistochemically coexpressed S100 protein and actin, but lacked SOX10 reactivity. Interestingly, the 2 PAX3-NCOA1-positive cases showed desmin reactivity and displayed a small component of rhabdomyoblastic cells, which were not seen in the more common PAX3-MAML3 fusion cases. In conclusion, we report a novel PAX3-NCOA1 fusion in BSNS, which appears to be associated with focal rhabdomyoblastic differentiation and should be distinguished from PAX3-NCOA1-positive alveolar rhabdomyosarcoma or malignant Triton tumor. SOX10 immunohistochemistry is a useful marker in distinguishing BSNS from peripheral nerve sheath tumors.

Infantile fibrosarcoma of ethmoid sinus, misdiagnosed as an adenoid in a 5-year-old child

Infantile fibrosarcoma of head and neck is rare and the presence of this tumor in ethmoid sinus is even more uncommon. To the best of our knowledge, <5 cases have been reported in the last 20 years in the English literature, so far, only one of which has been infantile type in a 15 months old girl. In this case report, we will explain our experience with a rare case of infantile fibrosarcoma originating from ethmoid sinus in a 5-year-old boy who presented with dyspnea and epistaxis. After biopsy, it was diagnosed as fibrosarcoma of sinus origin.

Paratesticular Spindle Cell Rhabdomyosarcoma

Spindle cell rhabdomyosarcoma is a rare variant of embryonal rhabdomyosarcoma that affects young males and most commonly involves the paratesticular region. We report a case of paratesticular spindle cell rhabdomyosarcoma in a 14-year-old boy, who presented with a painless scrotal mass. Left inguinal orchidectomy was performed. Histopathological and immunohistochemical examination of the mass revealed spindle cell rhabdomyosarcoma of the paratesticular region.

A Review: Molecular Aberrations within Hippo Signaling in Bone and Soft-Tissue Sarcomas

The Hippo signaling pathway is an evolutionarily conserved developmental network vital for the regulation of organ size, tissue homeostasis, repair and regeneration, and cell fate. The Hippo pathway has also been shown to have tumor suppressor properties. Hippo transduction involves a series of kinases and scaffolding proteins that are intricately connected to proteins in developmental cascades and in the tissue microenvironment. This network governs the downstream Hippo transcriptional co-activators, YAP and TAZ, which bind to and activate the output of TEADs, as well as other transcription factors responsible for cellular proliferation, self-renewal, differentiation, and survival. Surprisingly, there are few oncogenic mutations within the core components of the Hippo pathway. Instead, dysregulated Hippo signaling is a versatile accomplice to commonly mutated cancer pathways. For example, YAP and TAZ can be activated by oncogenic signaling from other pathways, or serve as co-activators for classical oncogenes. Emerging evidence suggests that Hippo signaling couples cell density and cytoskeletal structural changes to morphogenic signals and conveys a mesenchymal phenotype. While much of Hippo biology has been described in epithelial cell systems, it is clear that dysregulated Hippo signaling also contributes to malignancies of mesenchymal origin. This review will summarize the known molecular alterations within the Hippo pathway in sarcomas and highlight how several pharmacologic compounds have shown activity in modulating Hippo components, providing proof-of-principle that Hippo signaling may be harnessed for therapeutic application in sarcomas.

Orbital rhabdomyosarcoma with skin metastasis: a case report

Background

Rhabdomyosarcoma is a soft tissue neoplasm that usually arises in the headand neck region and genitourinary tract. Skin metastasis of rhabdomyosarcoma is extremely rare; of thirteen cases reported in the literature, most were children younger than 10 years and only three cases have been reported in adults.

Case presentation

A 20-year-old Moroccan man was admitted with a right orbital tumor. The tumor was excised and histopathology examination confirmed a diagnosis of rhabdomyosarcoma. The patient was treated with chemotherapy, but local recurrence occurred one year later. The patient underwent right orbital exenteration followed by chemotherapy and radiotherapy. After 6 months, the patient developed a cutaneous mass in the right lumbar region, which was resected. Immunohistochemical examination of the tumor showed this to be a cutaneous metastasis of rhabdomyosarcoma. The patient was treated by chemotherapy and there appeared to be no recurrence after 9 months of follow up.

Conclusions

Skin metastasis from rhabdomyosarcoma is extremely rare, particularly in adults. The purpose of presenting this case report is to raise awareness among clinicians— skin biopsy and immunohistochemistry are needed to distinguish this neoplasm from other cutaneous tumors so that appropriate treatment can be initiated.

An Adult Case of Paratesticular Spindle Cell Rhabdomyosarcoma

Paratesticular rhabdomyosarcoma (RMS) occurs more frequently in children and is rare in adults. Embryonal RMS is the most common subtype of paratesticular RMS. Spindle cell is a rare variant of embryonal RMS and is associated with a favorable prognosis in children. Data in adults is lacking. We present a case of paratesticular RMS in a 24-year-old man.

A recurrent neomorphic mutation in MYOD1 defines a clinically aggressive subset of embryonal rhabdomyosarcoma associated with PI3K-AKT pathway mutations

Rhabdomyosarcoma, a cancer of skeletal muscle lineage, is the most common soft-tissue sarcoma in children. Major subtypes of rhabdomyosarcoma include alveolar (ARMS) and embryonal (ERMS) tumors. Whereas ARMS tumors typically contain translocations generating PAX3-FOXO1 or PAX7-FOXO1 fusions that block terminal myogenic differentiation, no functionally comparable genetic event has been found in ERMS tumors. Here we report the discovery, through whole-exome sequencing, of a recurrent somatic mutation encoding p.Leu122Arg in the myogenic transcription factor MYOD1 in a distinct subset of ERMS tumors with poor outcomes that also often contain mutations altering PI3K-AKT pathway components. Previous mutagenesis studies had shown that MYOD1 with a p.Leu122Arg substitution can block wild-type MYOD1 function and bind to MYC consensus sequences, suggesting a possible switch from differentiation to proliferation. Our functional data now confirm this prediction. Thus, MYOD1 p.Leu122Arg defines a subset of rhabdomyosarcomas eligible for high-risk protocols and the development of targeted therapeutics.