Biphenotypic sinonasal sarcoma: an expanded immunoprofile including consistent nuclear β-catenin positivity and absence of SOX10 expression

Rhabdomyosarcoma in children and young adults

Rhabdomyosarcoma (RMS) is the most common soft tissue malignancy in childhood, accounting for 3% of all pediatric malignancies and 50% of all pediatric soft tissue sarcomas. In adolescents and young adults (AYA) however, RMS comprises only 6.5% of all soft tissue sarcomas. Historically, diagnosis and treatment of RMS was based on histologic recognition of the alveolar subtype, which was associated with a worse prognosis. Within the past 20 years, the biologic characteristics of RMS have become clearer, with canonical fusion drivers, PAX3/7::FOXO1, characterizing the alveolar subtype (ARMS) and in turn associated with poor outcome, while chromosomal gains/losses in addition to RAS pathway alterations characterize the embryonal subtype (ERMS). Accordingly, detection of a FOXO1 gene fusion has become a commonplace diagnostic and prognostic tool allowing tumors to be treated based on presence or absence of a FOXO1 gene fusion. However, these cytogenetic and molecular alterations represent only a portion of the molecular landscape found in RMS, and other alterations are found with increasing frequency in various subsets of RMS. Clinical trials basing risk stratification on the presence or absence of the canonical PAX3/7::FOXO1 fusions have had success in identifying the poor responders. Due to poor outcomes, the presence of MYOD1 and TP53 alterations which are common in spindle cell sclerosing RMS (SSRMS) and RMS with anaplasia have also been integrated into trial risk stratification. Therefore, complete histologic and immunophenotypic characterization remain important to better recognize and study these rare subsets of RMS. This article will discuss the challenges of RMS classification including how to combine morphologic, immunophenotypic and molecular data to arrive at an integrated diagnosis. The use of newer techniques such as liquid biopsy and methylation profiling, will also continue to shape the classification of RMS and may further refine risk stratification and prognosis.

Spindle Cell Neoplasms Unique to the Sinonasal Tract

The spindle cell neoplasms include sinonasal tract angiofibroma (STA), glomangiopericytoma (GPC), and biphenotypic sinonasal sarcoma (BSNS). These entities share some clinical, histomorphologic, immunohistochemical, and even molecular characteristics. Nevertheless, there are features that are unique to each tumor type. STA shows heavily collagenized and vascular stroma, with apparent relationship to underlying hormonal changes. GPC consistently exhibits monomorphic, ovoid cytologic appearance with the constant feature of Beta-catenin nuclear accumulation by IHC. Lastly, BSNS is a deceptively bland and neural-like neoplasm featuring consistent co-expression of S100 and smooth muscle markers with specific genetic rearrangements serving to uniquely characterize this entity.

Biphenotypic Sinonasal Sarcoma: Literature Review of a Peculiar Pathological Entity-The Neurosurgical Point of View

BACKGROUND

Biphenotypic sinonasal sarcoma (BSNS) is a low-grade tumor of the sinonasal tract with frequent extension to the orbit and skull base. Due to its rare incidence and recent histopathological and molecular characterization, little data are available in regard to its natural history, treatment and surveillance protocol.

METHODS

A comprehensive literature review in Embase online electronic databases on BSNS was made. The analyzed factors included the patients' sex and age, presenting symptoms and signs, anatomical origin and pattern of growth of the tumor, immunohistochemical and molecular features, time to treatment, type of treatment, surgical approach, extent of resection, peri- and post-operative complications, adjuvant therapies, clinical outcome, recurrence and overall survival rates.

RESULTS

This literature review involved 34 studies for an overall series of 149 cases of BSNS. The female (66.9%) and middle-aged populations (median 54.88 years old) were mainly affected. The most frequent clinical onset was nasal obstruction (81%), followed by facial discomfort (44%), epistaxis (15.5%) and ocular impairment (14.3%). Ethmoid sinus (67.8%) and nasal cavity (45.4%) were the most common anatomical site of tumor origin, while an extension to the orbit and skull base was registered in 28.7% and 24.5% of cases. Surgery was the main treatment, especially in the form of endoscopic endonasal approach (56.9%), and allowed for gross total resection in 79% of cases. The recurrence rate was 26.2%; three cases of tumor-related death were reported. Median follow-up was 4.6 years.

CONCLUSIONS

Biphenotypic sinonasal sarcoma is a rare and unique tumoral entity in terms of biological and clinical behavior. Based on the current knowledge, surgery plays the leading role in treatment, accounting for gross total tumor resection in most cases, allowing for clinical symptom and sign resolution and presenting a low rate of perioperative complications. The type of approach and the aim of surgery should be assessed case by case according to patient and pathology features and the surgeon's experience, as well as the aim of the treatment. Further studies including large surgical series and with long follow-up are required to define prognostic factors and guidelines of treatment for this peculiar pathological entity.

Novel PAX3::MAML3 Fusion Identified in Alveolar Rhabdomyosarcoma, Using DNA Methylation Profiling to Expand the Genetic Spectrum of "Fusion-Positive" Cases

Alveolar rhabdomyosarcoma (ARMS) with FOXO1 gene rearrangements is an aggressive pediatric rhabdomyosarcoma subtype that is prognostically distinct from embryonal rhabdomyosarcoma and fusion-negative ARMS. Here, we report 2 cases of ARMS with PAX3::MAML3 fusions. The tumors arose in an infant and an adolescent as stage IV metastatic disease (by Children's Oncology Group staging system). Histologically, both cases were small round blue cell tumors arranged in vague nests and solid sheets that were diffusely positive for desmin and myogenin. By methylation profiling and unsupervised clustering analysis, the tumors clustered with ARMS with classic FOXO1 rearrangements and ARMS with variant PAX3::NCOA1/INO80D fusions, but not with biphenotypic sinonasal sarcoma (BSNS) with PAX3::MAML3/NCOA2/FOXO1/YAP1 fusions nor with other small round blue cell tumors, including embryonal rhabdomyosarcoma. The differentially methylated genes between ARMS and BSNS were highly enriched in genes involved in myogenesis, and 21% of these genes overlap with target genes of the PAX3::FOXO1 fusion transcription factor. On follow-up after initiation of vincristine/actinomycin/cyclophosphamide chemotherapy, the tumors showed partial and complete clinical responses, consistent with typical upfront chemotherapy responsiveness of ARMS with the classic FOXO1 rearrangement. We conclude that PAX3::MAML3 is a novel variant fusion of ARMS, which displays a methylation signature distinct from BSNS despite sharing similar PAX3 fusions. These findings highlight the utility of methylation profiling in classifying ARMS with noncanonical fusions.

Biphenotypic sinonasal sarcoma diagnosed by detection of PAX3-MAML3 fusion gene using integrated whole-genome and transcriptome sequencing

Biphenotypic sinonasal sarcoma (BSNS) is a double-phenotype sarcoma that shows differentiation in both the nervous and muscular systems. To date, whole-genome and transcriptome sequencing (WGTS) has not been used to analyze BSNS. We report a patient with BSNS who was diagnosed based on PAX3 rearrangement using WGTS. A 71-year-old Japanese male without remarkable symptoms showed a nasal tumor when undergoing computed tomography. Although pathological examination revealed a non-characteristic spindle cell tumor, a definitive diagnosis could not be made based on this examination. Endoscopic sinus surgery was performed for subsequent diagnosis, treatment, and WGTS. WGTS revealed a t(2; 4)(q35; q31.1) reciprocal translocation, resulting in a PAX3-MAML3 fusion gene, leading to a definitive diagnosis of BSNS. We also detected upregulation of the expression of PAX3, MAML3, and 11 known genes involved in neural and myogenic differentiation relevant to the BSNS phenotype. Hence, using WGTS in combination with conventional pathological diagnosis can contribute to a definitive diagnosis of rare cancers, including BSNS, by detecting chromosomal rearrangements or diagnostic markers.

Biphenotypic Sinonasal Sarcoma with Orbital Invasion: A Literature Review and Modular System of Surgical Approaches

Background: Biphenotypic sinonasal sarcoma is a rare low-grade tumor arising from the sinonasal tract, featuring locally aggressive biological behavior, with a tendency to invade the orbit and skull base. There are no defined guidelines of treatment; thus, the management varies among different institutions. The aim of the present study is to provide a modular system of surgical approaches according to the lesion pattern of growth from a literature review. Materials and Methods: A comprehensive and detailed literature review on the PubMed and Embase online electronic databases on biphenotypic sinonasal sarcoma with orbital invasion was conducted. A personal case exhibiting peculiar features was also added. Demographic (patient's sex and age), clinical (presenting symptoms and time to treatment), neuroradiological (anatomical origin and pattern of growth), and treatment (type of treatment, surgical approach, extent of resection, peri- and postoperative complications, and adjuvant therapies) data, as well as clinical outcome, recurrence rates, and overall survival, were analyzed. Results: Thirty-one patients harboring biphenotypic sinonasal sarcoma with orbital invasion were identified. Tumors mainly affected female patients (66.7%) and a middle-aged population (median 55.2 years old). Simultaneous skull base involvement occurred in most cases (80.6%). Surgery was performed in all but one case (97%), as unique treatment (59%) or in association with radio-(23.5%) and/or chemotherapy (5.9%/2.9%), allowing for gross total tumor resection in most cases (66.7%). The endoscopic endonasal approach was the most adopted surgical corridor (51.7%). The local recurrence rate was 19.3%, and only two cases of tumor-related mortality occurred. Conclusions: Surgery is the only curative treatment, with the main goal to restore/improve/arrest progression of clinical manifestations. The endoscopic endonasal route represents the master approach for lesions confined to the midline. Microsurgical transcranial and endoscopic transorbital approaches have a complementary role for addressing the lesion's component with large intracranial extension or affecting the paramedian aspect of the anterior cranial fossa and superior-lateral orbital compartment, respectively. The approach selection should be made case by case according to the tumor pattern of growth.

Biphenotypic Sinonasal Sarcoma With High-Grade Features: A Diagnostic Challenge

Biphenotypic sinonasal sarcoma (BSNS) is a rare neoplasm of the sinonasal tract. These tumors show neural and myogenic differentiation and are characterized by PAX3 translocations. The immunophenotypic features reflect their dual differentiation. They are low-grade sarcomas that show monomorphic spindle cells in sheets, fascicles, and herringbone patterns and are positive for S100 and smooth muscle actin. These tumors are common in elderly female patients and have a locally aggressive course. High-grade presentation or transformation was not documented until recently. Total 3 BSNSs have now been documented in the literature and we report a fourth tumor with high-grade transformation 8 years after the initial presentation. We identify the morphologic and immunohistochemical features of the high-grade areas and we highlight the stark differences with the low-grade areas based on literature and our specimen. We also discuss the diagnostic challenges that may come up with such a presentation.

CD34-Positive Spindle Cell Tumor With CTNNB1 Mutation: An Unusual Spindle Cell Variant of Sinonasal Glomangiopericytoma

Sinonasal glomangiopericytoma is an uncommon mesenchymal tumor with a perivascular myoid phenotype, which is categorized as a borderline/low-grade malignant soft tissue tumor by the current World Health Organization Classification of Head and Neck tumors. Here, we present the case of a 53-year-old woman with an unusual spindle cell morphology of sinonasal glomangiopericytoma arising in the nasal cavity, mimicking solitary fibrous tumor. Microscopically, the tumor showed a cellular proliferation of spindle cells in fascicles including a focal long sweeping arrangement or whorls, or with a storiform growth pattern, associated with hemangiopericytoma-like gaping blood vessels embedded in a fibrous stroma. This arrangement of the spindle cells faintly indicated a solitary fibrous tumor rather than sinonasal glomangiopericytoma. Immunohistochemically, the tumor was positively reactive to not only beta-catenin (in the nuclei) but also CD34, although signal transducers and activators of transcription 6 was negative. Mutational analysis using Sanger sequencing detected a CTNNB1 mutation. We finally diagnosed the tumor as a sinonasal glomangiopericytoma, showing an unusual spindle cell variant. Such unusual spindle cell morphology with CD34-immunoreactivity potentially leads to an incorrect diagnosis of solitary fibrous tumor because such prominent fascicles including long sweeping structures, reminiscent of desmoid-type fibromatosis, have scarcely been described in the literature. Hence, careful morphological scrutiny using appropriate diagnostic adjuncts is necessary for correct diagnosis.

Integrated Molecular and Histological Insights for Targeted Therapies in Mesenchymal Sinonasal Tract Tumors

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of mesenchymal sinonasal tract tumors (STTs), a distinct subset of STTs. Despite their rarity, mesenchymal STTs represent a unique clinical challenge, characterized by their rarity, often slow progression, and frequently subtle or overlooked symptoms. The complex anatomy of the sinonasal area, which includes critical structures such as the orbit, brain, and cranial nerves, further complicates surgical treatment options. This underscores an urgent need for more advanced and specialized therapeutic approaches.

RECENT FINDINGS

Advancements in molecular diagnostics, particularly in next-generation sequencing, have significantly enhanced our understanding of STTs. Consequently, the World Health Organization has updated its tumor classification to better reflect the distinct histological and molecular profiles of these tumors, as well as to categorize mesenchymal STTs with greater accuracy. The growing understanding of the molecular characteristics of mesenchymal STTs opens new possibilities for targeted therapeutic interventions, marking a significant shift in treatment paradigms. This review article concentrates on mesenchymal STTs, specifically addressing sinonasal tract angiofibroma, sinonasal glomangiopericytoma, biphenotypic sinonasal sarcoma, and skull base chordoma. These entities are marked by unique histopathological and molecular features, which challenge conventional treatment approaches and simultaneously open avenues for novel targeted therapies. Our discussion is geared towards delineating the molecular underpinnings of mesenchymal STTs, with the objective of enhancing therapeutic strategies and addressing the existing shortcomings in the management of these intricate tumors.

A Minimally Invasive Endoscopic Transnasal and Transorbital Approach to Sinonasal Tumor Resection

A 35-year-old female with an extensive biphenotypic sinonasal sarcoma (BSNS) eroding through the left frontal sinus into the orbit required gross total resection of the tumor. We wanted to forgo an open approach and provide a less invasive alternative via combined endonasal and transorbital endoscopic techniques to allow for tumor removal through small, well-disguised incisions. We utilized three portals-nasal, transorbital, and anterior table window-to create interconnected orbit-sinonasal corridors, thus generating alternate pathways for visualization and manipulation of this extensive tumor. Laryngoscope, 134:1308-1312, 2024.

International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors

BACKGROUND

Sinonasal neoplasms, whether benign and malignant, pose a significant challenge to clinicians and represent a model area for multidisciplinary collaboration in order to optimize patient care. The International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors (ICSNT) aims to summarize the best available evidence and presents 48 thematic and histopathology-based topics spanning the field.

METHODS

In accordance with prior International Consensus Statement on Allergy and Rhinology documents, ICSNT assigned each topic as an Evidence-Based Review with Recommendations, Evidence-Based Review, and Literature Review based on the level of evidence. An international group of multidisciplinary author teams were assembled for the topic reviews using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses format, and completed sections underwent a thorough and iterative consensus-building process. The final document underwent rigorous synthesis and review prior to publication.

RESULTS

The ICSNT document consists of four major sections: general principles, benign neoplasms and lesions, malignant neoplasms, and quality of life and surveillance. It covers 48 conceptual and/or histopathology-based topics relevant to sinonasal neoplasms and masses. Topics with a high level of evidence provided specific recommendations, while other areas summarized the current state of evidence. A final section highlights research opportunities and future directions, contributing to advancing knowledge and community intervention.

CONCLUSION

As an embodiment of the multidisciplinary and collaborative model of care in sinonasal neoplasms and masses, ICSNT was designed as a comprehensive, international, and multidisciplinary collaborative endeavor. Its primary objective is to summarize the existing evidence in the field of sinonasal neoplasms and masses.

Nasal spindle cell tumor: A case report and literature review

BACKGROUND

Spindle cell tumors are rare and can occur in any organ or tissue. Due to their rarity the clinicopathological features and diagnostic protocols have not been adequately studied. However, it has become necessary to develop differential diagnosis of spindle cell tumors. Here, we report a case of a nasal spindle cell tumor diagnosed at our hospital in attempt to contribute to this gap in literature.

KEY POINTS FROM THE CASE

A male in his 30s was admitted to our hospital with nasal obstruction that had persisted for several years. Electronic fibrolaryngoscopy revealed a smooth neoplasm within the nasal cavity.

MAIN LESSONS TO BE LEARNED FROM THIS CASE REPORT

The results of this case emphasize that spindle cell tumors have large morphological variations, and it is difficult to determine the origin of tumor cells using hematoxylin and eosin staining alone. Therefore, it is necessary to improve the immunohistochemistry and combine it with clinical symptoms to diagnose the disease.

Novel NCOA2/3-rearranged low-grade fibroblastic spindle cell tumors: A report of five cases

Spindle cell mesenchymal neoplasms are a diverse and often challenging diagnostic group. While morphological impression is sufficient for some diagnoses, increasingly immunohistochemical and even molecular data is required to render an accurate diagnosis, which can lead to the characterization of new entities. We describe five cases of novel mesenchymal neoplasms with rearrangements in the NCOA2 and NCOA3 genes partnered with either CTCF or CRTC1. Three tumors occurred in the head and neck (palate, auditory canal), while the other two were in visceral organs (lung, urinary bladder). All cases occurred in adults (range 33-86) with a median age of 42 and fairly even sex distribution = (male-to-female = 3:2). Morphologically, they had similar features consisting of monotonous, bland spindle to ovoid cells with fascicular and reticular arrangements in a myxohyaline to collagenous stroma. However, immunophenotypically they had essentially a null phenotype, with only two tumors staining partially for CD34 and smooth muscle actin. Targeted RNA sequencing detected in-frame CTCF::NCOA2 (one case), CRTC1::NCOA2 (two cases), and CTCF::NCOA3 (two cases) fusions. Treatment was surgical resection in all cases. Local recurrence and/or distant metastases were not observed in any case (median follow-up, 7.5 months; range, 2-19 months). Given their morphologic, immunohistochemical, and molecular similarities, we believe that these cases may represent an emerging family of low-grade NCOA2/3-rearranged fibroblastic spindle cell neoplasms.

Biphenotypic Sinonasal Sarcoma with Orbital and Skull Base Involvement Report of 3 Cases and Systematic Review of the Literature

Biphenotypic sinonasal sarcoma (BSNS) is a rare malignant tumour of the upper nasal cavity and ethmoid sinuses that presents predominantly in middle aged female patients and show a characteristic infiltrative and hypercellular proliferation of spindle cells that demonstrate a specific immunoreactivity. We present three cases with BSNS that had different presenting complaints, either sinonasal or orbital problems, underwent endoscopic surgical treatment and/or radiotherapy and have been disease free on long follow up. A systematic review of all published cases was performed to identify all BSNS cases known at present. BSNS requires prompt and correct diagnosis with accurate surgical resection as well as consideration of radiotherapy. Our three cases confirm the findings of the literature and support that BSNS is an aggressive but treatable malignant disease of the sinonasal tract.

Sinonasal nodular fasciitis: report of a case with USP6 rearrangement

Nodular fasciitis (NF) is a benign myofibroblastic proliferation characterized by rapid growth, a self-limiting course, and USP6 gene rearrangement. Although it can arise in the head and neck region, very few cases of NF involving the sinonasal tract have been reported to date. Herein we report a case of NF involving the nasal cavity presenting as a polypoid well-defined mass causing obstructive symptoms in a male with a history of multiple local surgeries. Although the mass had an unusual clinical presentation, the histopathologic and immunohistochemical findings were consistent with NF. Fluorescent in situ hybridization performed with break-apart probes flanking the USP6 locus on chromosome 17p13 revealed the presence of USP6 gene rearrangement. The patient remained free of disease 124 months after surgical treatment. Considering its remarkably benign behavior despite its alarming clinical and histologic features, the distinction of NF from sinonasal malignant tumors is essential.

Biphenotypic Sinonasal Sarcoma with a Novel PAX7::PPARGC1 Fusion: Expanding the Spectrum of Gene Fusions Beyond the PAX3 Gene

Biphenotypic sinonasal sarcoma (BSNS) is a rare low-grade malignancy occurring in the sinonasal tract that is characterized by dual neural and myogenic differentiation. Rearrangements involving the PAX3 gene, usually with MAML3, are a hallmark of this tumor type and their identification are useful for diagnosis. Rarely, a MAML3 rearrangement without associated PAX3 rearrangement has been described. Other gene fusions have not been previously reported. Herein, we report a 22 year-old woman with a BSNS harboring a novel gene fusion involving the PAX7 gene (specifically PAX7::PPARGC1A), which is a paralogue of PAX3. The histologic features of the tumor were typical with two exceptions: a lack of entrapment of surface respiratory mucosa and no hemangiopericytoma-like vasculature. Immunophenotypically, the tumor was notably negative for smooth muscle actin, which is usually positive in BSNS. However, the classic S100 protein-positive, SOX10-negative staining pattern was present. In addition, the tumor was positive for desmin and MyoD1 but negative for myogenin, a pattern that is common among BSNS with variant fusions. Awareness of the possibility of PAX7 gene fusions in BSNS is important as it may aid in the diagnosis of PAX3 fusion negative tumors.

Translocations and Gene Fusions in Sinonasal Malignancies

PURPOSE OF REVIEW

During the past few years there has been an expansion in our understanding of gene fusions and translocations involved in cancer of the sinonasal tract. Here we review the downstream biologic effects, clinical characteristics, and pathologic features of these tumors. The molecular consequences and neo-antigens resulting from these chromosomal aberrations are considered and targets for current and future clinical trials discussed.

RECENT FINDINGS

Several new, clinically relevant, chromosomal aberrations have been discovered and evaluated to varying degrees in sinonasal tumors including DEK::AFF2, BRD4::NUT, ADCK4::NUMBL, and ETV6::NTRK3. Sinonasal malignancies demonstrate a diverse genetic landscape and varying clinical courses. Recent studies illustrate that gene fusions and translocations may play a role in carcinogenesis in certain sinonasal tumor subtypes and may be used to develop new biomarker-driven and patient-centered treatments.

Top 10 Significant Spindled Head and Neck Lesions to Scrutinze

BACKGROUND

Spindled lesions are a challenging area in head and neck pathology. This is particularly true in the sinonasal tract, where several uncommon entities with both unique and overlapping morphologic, immunophenotypic, and/or molecular features can occur.

METHODS

Review.

RESULTS

The clinicopathologic characteristics of biphenotypic sinonasal sarcoma and nine important differential diagnostic considerations with one or more overlapping feature are summarized to establish a practical framework for approaching spindled lesions of the sinonasal tract.

CONCLUSION

Morphologic evaluation is central to the work up of sinonasal spindle cell lesions-in particular, cellular morphology, tumor architecture and growth pattern, and the presence of admixed epithelial elements - however, focused immunohistochemical analysis of neural, myogenic, rhabdomyoblastic, epithelial, and/or melanocytic marker expression and/or ancillary tests for tumor-specific molecular alterations may be necessary for definitive diagnosis.

Biphenotypic Sinonasal Sarcoma with a Novel PAX3::FOXO6 Fusion: A Case Report and Review of the Literature

BACKGROUND

Biphenotypic sinonasal sarcoma (BSS) is a low-grade, locally aggressive sarcoma unique to the sinonasal region. BSS is most common in middle aged patients and affects women more frequently than men. It is characterized by a bland spindled cell proliferation with neural and myogenic differentiation. BSS are usually associated with rearrangement t(2;4)(q35;q31.1) resulting in a PAX3::MAML3 fusion. Less commonly, other genes are found in combination with PAX3 and some cases reported in the literature have an unknown fusion partner.

METHODS

A 54-year-old man presented with nasal mass. Endoscopic resection showed a low-grade spindle cell neoplasm with morphologic features of BSS and immunohistochemical and next generation sequencing were performed to confirm the diagnosis.

RESULTS

The tumor was positive for S100 and smooth muscle actin but negative for SOX10. Next generation sequencing demonstrated a novel PAX3::FOXO6 gene fusion.

CONCLUSIONS

Although a PAX3::FOXO6 gene fusion has never been reported, this finding combined with the morphologic and immunophenotypic features supports the diagnosis of supports the diagnosis of BSS.

Case report: pseudoendocrine sarcoma, a clinicopathologic report of a newly described soft tissue neoplasm

Papke et al. recently reported a series of twenty-three soft tissue lesions chiefly arising in older adults featuring distinct morphological and genetic characteristics. Pseudoendocrine sarcoma (PS) is the somewhat descriptive and provisional term adopted for the newly reported mesenchymal neoplasm. Since the publication of the original paper published in January 2022, a single case of PS has been published. Pseudoendocrine sarcoma shows a predilection for the paravertebral deep soft tissues of the trunk, low-grade neuroendocrine-like histological features, and hallmark CTNNB1 activating mutations.Herein, we will discuss a case of a 72-year-old woman presenting with a 4-cm laterocervical mass. Hematoxylin and eosin slides showed a multilobular proliferation of monomorphic epithelioid cells with speckled chromatin arranged in nests and trabeculae. Immunohistochemical staining and molecular analysis were consistent with the newly proposed entity.

Biphenotypic sinonasal sarcoma: European multicentre case-series and systematic literature review

Objective

Biphenotypic sinonasal sarcoma (BSNS) is a rare low-grade cancer that was included from the 4th edition of WHO classification of head and neck tumours. The purpose of this study is to analyse clinical behaviour, pattern of recurrences and survival outcomes of this neoplasm.

Methods

Retrospective review of patients affected by BSNS who were treated via an endoscopic-assisted approach in 6 European tertiary-care referral hospitals. Cases of BSNS described in literature since 2012 to date were fully reviewed, according to PRISMA guidelines.

Results

A total of 15 patients were included. Seven patients were treated via an endoscopic endonasal approach, 4 with endoscopic transnasal craniectomy, and 4 via a cranio-endoscopic approach. Adjuvant treatment was delivered in 2 cases. After a mean follow-up of 27.3 months, systemic metastasis was observed in 1 case; the 5-year overall survival and disease-free survival rates were 100% and 80 ± 17.9%, respectively.

Conclusions

BSNS is a locally aggressive tumour with a low recurrence rate and encouraging survival outcomes if properly treated with surgical resection and free margins followed by adjuvant radiotherapy for selected cases. Endoscopic-assisted surgery is safe and effective as an upfront treatment within a multidisciplinary care protocol.

Small Biopsy Samples: Are They Representative for Biphenotypic Sinonasal Sarcoma?

(1) Background: Biphenotypic sinonasal sarcoma (BSNS) is a rare low-grade neoplasm of the sinonasal tract. It is characterized by specific PAX3 gene rearrangements and both myogenic and neural differentiation. The purpose of the study was to describe the histologic, immunohistochemical and molecular features of BSNS and indicate important clues for small incisional biopsy diagnostics. (2) Methods: Archival samples from patients with nasal cavities or ethmoid sinuses tumors were searched for BSNS cases. Inclusion criteria were the presence of spindle cell morphology and low-grade appearance. Both biopsy and resection specimens were stained for identical IHC panels including, i.a., S100, SMA, SOX10 and PAX3. FISH for PAX3 and SS18 was performed on biopsy specimens. (3) Results: BSNS diagnosis was made in 6 cases included in the study and confirmed by PAX3 rearrangement by FISH in 5 specimens. The pattern of IHC expression was identical for paired biopsy and resection samples apart from one BSNS case. (4) Conclusions: Incisional biopsy seems to be a sufficient method to establish BSNS diagnosis in most cases. Characteristic morphological features together with S100, SOX10 and SMA as the screening markers are useful for confirming the diagnosis. In cases of divergent morphology and immunoprofile evaluation of PAX3 rearrangement is vital.

Transcriptomic analysis of mRNA expression in giant congenital melanocytic nevi

BACKGROUND AND OBJECTIVE

GCMN is a sporadic disease with an incidence ranging from 1/20,000 to 1/500000. So far, several studies have found that GCMN is related to somatic mutations, but most of them have focused on known pathogenic genes, and transcriptome sequencing based on large datasets is relatively uncommon. At present, the use of next-generation sequencing technologies and bioinformatics platforms makes genomic information study more comprehensive and efficient. In this study, the transcriptome differences between GCMN lesions and surrounding normal skin tissues were investigated using high-throughput transcriptome sequencing, and hub genes and pathways related to pathogenesis were identified, providing a theoretical foundation for further research into the pathogenesis of GCMN.

METHODS

Pathological skin tissue and surrounding normal skin tissue from GCMN patients, namely the pathological group (PG) and the control group (CG), were obtained. 1. All specimens were stained with HE to ensure that the samples met the experimental requirements. 2. Ten pairs of specimens were selected for high-throughput transcriptome sequencing, and the differentially expressed genes (DEGs) between the PG and the CG were obtained. The DEGs were analyzed by clusterProfiler R software for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The function of the subnetwork was analyzed and the hub genes were identified by the STRING database and Cytoscape software. 3. The expression differences of hub genes PTGS2, EGF, and SOX10 in pathological skin tissues and normal skin tissues were verified by qRT-PCR and immunofluorescence staining.

RESULTS

1. HE staining revealed a lot of melanocytes in the dermis and subcutaneous tissues. They were found around the hair follicles, sweat glands, sebaceous glands, and blood vessel walls, or in a specific pattern. 2. The screening threshold was set at p<0.01 and |log2fc|<1, and a total of 1163 DEGs were discovered between the PG and CG, with 519 genes up-regulated and 644 genes down-regulated in the pathological tissues. According to the GO functional analysis, 29 biological processes, 18 cell compositions, and 17 molecular functions were significantly enriched, with the majority of them being related to keratinocytes and the extracellular matrix. There were 779 nodes and 2359 interactions in the protein interaction network. Using the MCODE plug-in, the network was divided into 25 functional clusters. According to ClueGO results, Cluster5 was involved in melanin biosynthesis and melanocyte proliferation. Using 11 operation methods in the Cytohubba plug-in, PTGS2, EGF, and SOX10 in Cluster5 were chosen as hub genes. 3. qRT-PCR and immunofluorescent staining revealed that compared to normal skin tissue, the expression of SOX10 was significantly up-regulated, and the expression of PTGS2 and EGF was significantly down-regulated in pathological skin tissue(P<0.001).

CONCLUSIONS

In GCMN, keratinocytes and extracellular matrix may directly and indirectly affect melanocyte activity. PTGS2, EGF, and SOX10 are important genes and significantly differentially expressed in pathological and normal skin tissues. These findings may serve as a springboard for future research.

Biphenotypic Sinonasal Sarcoma with Intracranial Extension - A Case Report with Review of Literature

Rationale

Biphenotypic sinonasal sarcoma is a rare malignant tumour exclusively involving the sinonasal cavity. These tumours have variable and atypical presentations. Early approach and correct treatment modalities are key factors in the management of such cases.

Patient Concern

A 48-year-old male patient presented with left-sided nasal obstruction and intermittent nasal bleeding for one year.

Diagnosis

Biphenotypic sinonasal sarcoma confirmed on histopathological examination and immunohistochemistry.

Treatment

The patient underwent surgical excision with left lateral rhinotomy and bifrontal craniotomy with skull base repair. The patient also received postoperative radiotherapy.

Outcome

The patient is on regular follow-up with no similar complaints.

Take-Away Lesson

Treating team should keep the diagnosis of biphenotypic sinonasal sarcoma in mind while investigating a patient with nasal mass. Surgical management is the treatment of choice, due to its local aggressive nature and proximity to the brain and eyes. Postoperative radiotherapy is vital to prevent tumour recurrence.

High-Grade Biphenotypic Sinonasal Sarcoma: A Case Report

Introduction  Biphenotypic sinonasal sarcoma (BSNS) is a recently found entity that first described by Lewis et al. It was then added to the 4th edition of the World Health Organization (WHO) of head and neck tumors in 2012. BSNS has been described as a rare low-grade sarcoma arising in the upper sinonasal tract. It is believed that in the past, BSNS was, likely, previously diagnosed as other low-grade or benign malignancies. Fibrosarcoma, leiomyosarcoma, and peripheral nerve sheath tumors, all fall within the differential diagnosis of BSNS. However, BSNS is unlike other mesenchymal sinonasal tumors, as it displays both neural and myogenic differentiation. BSNS has thus far been recognized in only a hand full of case reports, all of which have reported similar morphologic features of a low-grade soft tissue tumor with neural involvement arising from the nasal cavity or ethmoid air cells in middle aged individuals. In fact, being low-grade sarcoma became such a hallmark characteristic of this tumor that it even received the name low-grade sinonasal sarcoma with neural and myogenic features or LGSSNMF.

Case Presentation  We present, however, for the first time, a high-grade differentiation of BSNS in an otherwise healthy 72-year-old female. The patient was referred from an outside ENT (ear, nose, and throat) after pathology from a presumed polypectomy returned positive for a BSNS. Initial imaging revealed erosion through the bilateral lamina papyracea, anterior cranial fossa floor, and posterior table of the frontal sinus. She then underwent a combined endoscopic and bicoronal open approach for resection of the skull base lesion that was found to encompass the entirety of the sinonasal cavities bilaterally. Postoperatively, the patient underwent significant complications including infection of the pericranial flap, pneumocephalus, and eventually death.

Discussion  As BSNS is a fairly new entity, currently there has only been four case series conducted, each identifying features of a low-grade sarcoma with both myogenic and neural differentiation. Histologically, BSNS has monophasic spindle cells with uniform, elongated nuclei with scant cytoplasm between benign proliferations of surface-type respiratory epithelium, with a low mitotic rate. Our case, however, revealed pleomorphic hyperchromatic cells with high mitotic activity and necrosis with invasion of bone, staging it as high grade. Immunohistochemistry also differed from the previously reported standards. This case describes a new category for BSNS which may change the differential diagnosis, management, and surgical recommendations that are currently utilized for this skull base neoplasm.

Leiomyosarcoma of the Nasal Cavity and Paranasal Sinuses: A Case Report and Comprehensive Review of the Literature

Sinonasal leiomyosarcoma (LMS) is a rare and aggressive mesenchymal tumor with smooth muscle differentiation. The sinonasal tract is an unusual primary site for LMS, as scant smooth muscle exists in this location, with only 75 cases reported in the English literature including the case presented herein. Sinonasal LMS is considered an aggressive head and neck tumor with significant potential for recurrence and metastasis. Since recurrence is high and the potential for late metastasis exists, lifelong follow-up in these patients would be beneficial, especially among those with previous history of RB.

Molecular Biomarkers in Sinonasal Cancers: New Frontiers in Diagnosis and Treatment

Purpose of Review

Sinonasal tumors are rare and heterogeneous diseases which pose challenges in diagnosis and treatment. Despite significant progress made in surgical, oncological, and radiotherapy fields, their prognosis still remains poor. Therefore, alternative strategies should be studied in order to refine diagnosis and improve patient care.

Recent Findings

In recent years, in-depth molecular studies have identified new biological markers, such as genetic abnormalities and epigenetic variations, which have allowed to refine diagnosis and predict prognosis. As a consequence, new histological entities have been described and specific subgroup stratifications within the well-known histotypes have been made possible. These discoveries have expanded indications for immunotherapy and targeted therapies in order to reduce tumor spread, thus representing a valuable implementation of standard treatments.

Summary

Recent findings in molecular biology have paved the way for better understanding and managing such rare and aggressive tumors. Although further efforts need to be made in this direction, expectations are promising.

Biphenotypic sinonasal sarcoma: Report of 3 cases with a review of literature

Biphenotypic sinonasal sarcoma (BSNS) is a rare recently described distinct spindle cell sarcoma which arises exclusively in the sinonasal region and is characterized by concomitant neural and myogenic differentiation. Before this neoplasm was characterized, most were classified as other entities including adult fibrosarcoma, monophasic synovial sarcoma and malignant peripheral nerve sheath tumor. By immunohistochemistry, these tumors characteristically express S100 and smooth muscle actin (SMA) and/or muscle specific actin (MSA). Most cases harbor rearrangements of PAX3 (paired box gene 3), and the most frequent translocation partner is MAML3 (mastermind like transcriptional coactivator 3). Herein, we described three cases of BSNS involving the nasal cavity with or without paranasal sinus involvement. We also did a literature review of the clinical features, histologic and immunophenotypic findings, cytogenetics, pathogenesis and behavior of this rare entity.

Orbital Involvement by Biphenotypic Sinonasal Sarcoma With a Literature Review

PURPOSE

To document a case of a biphenotypic sinonasal sarcoma that impinged on the orbit via a tumor-induced mucocele and review the previous literature devoted to this condition.

METHODS

A clinicopathologic case report with detailed histopathologic, immunohistochemical, and radiological studies with tabulations of previously reported cases and immunohistochemical stains for ruling out mimicking lesions.

RESULTS

A biphenotypic sinonasal sarcoma arose from the ethmoid sinus in a middle-aged man. The tumor induced a mucocele that bowed the medial orbital lamina papyracea into the orbit and caused diplopia and mild proptosis. The biopsy's dual positivity for S100 and smooth muscle actin together with positive paired box 3 immunohistochemical staining established the diagnosis of biphenotypic sinonasal sarcoma.

CONCLUSION

Biphenotypic sinonasal sarcoma, which can involve the orbit in 25% of cases, is a rare head and neck malignancy that has only recently been described. Biphenotypic sinonasal sarcoma is a low-grade, locally aggressive, nonmetastasizing sarcoma displaying both neural and muscle differentiation. It is further characterized by rearrangements of the PAX3 gene with multiple fusion partners, most commonly MAML3 (Mastermind like transcriptional coactivator 3). It occurs predominantly in middle-aged women and exclusively in the sinonasal tract. However, it can spread throughout the central facial structures to invade the brain if not detected early. Ophthalmologists should be aware of this new entity to avoid delays in diagnosis and treatment. The previous literature devoted to this condition was reviewed and analyzed for clinical, radiological, histopathological, and immunohistochemical features. In circumstances where molecular testing is not available, paired box 3 immunohistochemical staining can be used as an alternative diagnostic marker. The current case is most unusual because the orbital findings were induced by a mucocele caused by the tumor that obstructed the sinus ostium. This produced diplopia without direct tumor invasion into the orbital fat.

Emerging Entities and New Diagnostic Markers for Head and Neck Soft Tissue and Bone Tumors

Bone and soft tissue tumors of the head and neck are relatively uncommon tumors that often represent a diagnostic challenge because of the wide range of entities that must be considered in the differential diagnosis. Over the past few years, classification of bone and soft tissue tumors has evolved primarily because of substantial contributions from molecular genetics, with the identification of new markers that are increasingly used to complement histopathologic findings in the routine diagnostic workup. This review focuses on the recently described mesenchymal tumors that preferentially involve the head and neck region, with a focus on the most relevant novel immunohistochemical and molecular findings, including gene fusions and mutations, that can help in the diagnosis and in the assessment of clinical behavior.

RREB1-MKL2 fusion in a spindle cell sinonasal sarcoma: biphenotypic sinonasal sarcoma or ectomesenchymal chondromyxoid tumor in an unusual site?

Biphenotypic sinonasal sarcoma (BSNS) is a rare, low grade spindle cell sarcoma, recently recognized in the WHO classification of head and neck tumors, which is characterized by a dual myogenic and neural differentiation and recurrent gene fusions, often involving PAX3-MAML3, and less commonly PAX3 fusions with other partners such as NCOA1, NCOA2, or WWTR1. Yet, in about 4% of tumors no gene rearrangements are identified. Herein, we describe a RREB1-MKL2 fusion in a BSNS lesion occurring in a 73-year-old female patient with a right maxillo-ethmoidal angle lesion. The polypoid, moderately cellular tumor with infiltrative submucosal growth was composed of fascicles of relatively bland spindle cells embedded in a loose collagenous matrix. The tumor cells showed moderate amounts of eosinophilic cytoplasm with indistinct borders and uniform, pale, ovoid to slender nuclei. The slowly proliferating neoplastic cells co-expressed smooth muscle actin and S100, and showed focal nuclear positivity for ß-catenin, while lacking staining for cytokeratins, desmin, myogenin, caldesmon, glial fibrillary acid protein, and SOX-10. Molecular analysis by targeted RNA-based next-generation sequencing identified an in-frame fusion between exon 8 of RREB1 and exon 11 of MKL2, a genetic event that was reported to be a molecular hallmark of ectomesenchymal chondromyxoid tumor. Gene rearrangements in both genes were independently verified by fluorescence in situ hybridization (FISH). To evaluate its recurrent potential an additional group of 15 fusion negative BSNS were tested for abnormalities in RREB1 and MKL2 genes by FISH, but no additional positive cases were identified.

Biphenotypic Sinonasal Sarcoma: A Case Report and Review of Literature

OBJECTIVES

Biphenotypic sinonasal sarcoma (BSNS), previously low-grade sinonasal sarcoma with neural and myogenic features, is a rare tumor of the sinonasal tract first described in 2012. Due to its rarity, limited literature is available in providing clinicians with a standardized treatment regimen, particularly in cases of positive surgical margins. This article aims to provide a clinical review of the currently available reported cases of BSNS, as well as presenting clinical, radiologic, and pathologic details of 2 novel cases.

METHODS

Online electronic databases include PubMed and Embase where queried for reports of biphenotypic sinonasal sarcoma or low-grade sinonasal sarcoma with neural and myogenic features. Two previously unpublished cases were included in the results. Data including clinical presentation, epidemiologic data, radiologic evaluation, intraoperative details, histopathology, treatment modality, and postoperative follow-up information were included.

RESULTS

A total of 100 previously published cases were identified in 12 prior articles. Mean age at presentation was 52.9 years. Extrasinonasal extension was observed in 27.4% of cases with most common site of extension being cribriform plate. Forty-seven cases included treatment details with surgical excision being the most common modality. Recurrence rates were identical for both surgical excision alone and surgical excision with adjuvant radiotherapy (33.3%).

CONCLUSIONS

Biphenotypic sinonasal sarcoma is a slow-growing tumor that is amenable to surgical resection. Recurrence rates are similar between surgical excision and surgical excision with adjuvant radiation therapy, but limited data in reported cases preclude a determination of treatment superiority.

Rare Diseases of the Nose, the Paranasal Sinuses, and the Anterior Skull Base

Due to their low incidence and thus resulting limited diagnostic criteria as well as therapeutic options, rare diseases of the nose, the paranasal sinuses, and the anterior skull base are a significant challenge. The value as of which a disease has to be considered as rare amounts to a maximum of 5 patients per 10 000 people. Within these diseases, however, there are extreme differences. Some rare or orphan diseases like for example the inverted papilloma belong to regularly diagnosed and treated diseases of larger departments of oto-rhino-laryngology whereas other rare diseases and malformations have only been described in less than 100 case reports worldwide. This fact emphasizes the necessity of bundling the available experience of diagnostics and therapy. The present article gives an overview about rare diseases of the nose, the paranasal sinuses, and the anterior skull base from the field of diseases/syndromes of the olfactory system, malformations of the nose and paranasal sinuses, ventilation and functional disorders as well as benign and malignant tumors. The classification and data on diagnostic and therapeutic options were established based on the current literature.

Sex-Determining Region Y Chromosome-Related High-Mobility-Group Box 10 in Cancer: A Potential Therapeutic Target

Sex-determining region Y-related high mobility group-box 10 (SOX10), a member of the SOX family, has recently been highlighted as an essential transcriptional factor involved in developmental biology. Recently, the functionality of SOX 10 has been increasingly revealed by researchers worldwide. It has been reported that SOX10 significantly regulates the proliferation, migration, and apoptosis of tumors and is closely associated with the progression of cancer. In this review, we first introduce the basic background of the SOX family and SOX10 and then discuss the pathophysiological roles of SOX10 in cancer. Besides, we enumerate the application of SOX10 in the pathological diagnosis and therapeutic potential of cancer. Eventually, we summarize the potential directions and perspectives of SOX10 in neoplastic theranostics. The information compiled herein may assist in additional studies and increase the potential of SOX10 as a therapeutic target for cancer.

Expression Patterns of Coagulation Factor XIII Subunit A on Leukemic Lymphoblasts Correlate with Clinical Outcome and Genetic Subtypes in Childhood B-cell Progenitor Acute Lymphoblastic Leukemia

BACKGROUND

Based on previous retrospective results, we investigated the association of coagulation FXIII subunit A (FXIII-A) expression pattern on survival and correlations with known prognostic factors of B-cell progenitor (BCP) childhood acute lymphoblastic leukemia (ALL) as a pilot study of the prospective multi-center BFM ALL-IC 2009 clinical trial.

METHODS

The study included four national centers (n = 408). Immunophenotyping by flow cytometry and cytogenetic analysis were performed by standard methods. Copy number alteration was studied in a subset of patients (n = 59). Survival rates were estimated by Kaplan-Meier analysis. Correlations between FXIII-A expression patterns and risk factors were investigated with Cox and logistic regression models.

RESULTS

Three different patterns of FXIII-A expression were observed: negative (<20%), dim (20-79%), and bright (≥80%). The FXIII-A dim expression group had significantly higher 5-year event-free survival (EFS) (93%) than the FXIII-A negative (70%) and FXIII-A bright (61%) groups. Distribution of intermediate genetic risk categories and the "B-other" genetic subgroup differed significantly between the FXIII-A positive and negative groups. Multivariate logistic regression confirmed independent association between the FXIII-A negative expression characteristics and the prevalence of intermediate genetic risk group.

CONCLUSIONS

FXIII-A negativity is associated with dismal survival in children with BCP-ALL and is an indicator for the presence of unfavorable genetic alterations.

Radiation therapy strategies for skull-base malignancies

INTRODUCTION

The management of skull base malignancies continues to evolve with improvements in surgical technique, advances in radiation delivery and novel systemic agents.

METHODS

In this review, we aim to discuss in detail the management of common skull base pathologies which typically require multimodality therapy, focusing on the radiotherapeutic aspects of care.

RESULTS

Technological advances in the administration of radiation therapy have led to a wide variety of different treatment strategies for the treatment of skull base malignances, with outcomes summarized herein.

CONCLUSION

Radiation treatment plays a key and critical role in the management of patients with skull base tumors. Recent advancements continue to improve the risk/benefit ratio for radiotherapy in this setting.

Clinicopathologic and Molecular Features of a Series of 41 Biphenotypic Sinonasal Sarcomas Expanding Their Molecular Spectrum

Biphenotypic sinonasal sarcoma (BSNS) is a locally aggressive tumor occurring in the sinonasal region. It harbors both myogenic and neural differentiation and is characterized by PAX3 rearrangement with MAML3 as the most frequent fusion partner, but the partner of PAX3 remains unidentified in a subset of cases. About 70 cases have been reported so far. In this study, we report a series of 41 cases with clinical, pathologic, and molecular description. Twenty-five (61%) patients were female individuals, and the median age was 49 years. Tumors arose predominantly in the nasal cavity and ethmoidal sinuses. Local recurrences occurred in 8 cases of the 25 (32%). Histologic features were characteristic of BSNS, with 5 cases showing focal rhabdomyoblastic differentiation. Immunohistochemistry showed a constant positivity of S100 protein and PAX3 and negativity of SOX10. MyoD1 was focally positive in 91% of cases, whereas only 20% were positive for myogenin. Molecular analysis showed a PAX3-MAML3 transcript in 37 cases (90%). RNA sequencing was performed in the 4 negative cases for PAX3-MAML3 fusion, and it showed that 1 case harbored a PAX3-FOXO1 fusion, as previously described in the literature, and 2 novel fusions: PAX3-WWTR1 fusion in 2 cases and PAX3-NCOA2 fusion in 1 case. RNA sequencing results were confirmed by fluorescence in situ hybridization, reverse transcription-polymerase chain reaction, and Sanger sequencing. The PAX3-NCOA2-positive case showed focal rhabdomyoblastic differentiation. In conclusion, we report 2 novel fusions (PAX3-WWTR1 and PAX3-NCOA2) in BSNS and show that MyoD1 is more sensitive than myogenin for demonstrating myogenic differentiation in this tumor.

Soft Tissue Special Issue: Biphenotypic Sinonasal Sarcoma: A Review with Emphasis on Differential Diagnosis

Biphenotypic sinonasal sarcoma is an anatomically restricted low-grade malignant neoplasm with dual neural and myogenic differentiation composed of a monotonous population of spindled cells with herringbone/fascicular architecture. These tumors demonstrate a unique immunoprofile with relatively consistent S100-protein and actin expression in conjunction with more variable desmin, myogenin and myoD1 staining. SOX10 is uniformly negative. Genetically, the majority of tumors harbor PAX3-MAML3 fusions, with alternate PAX3 partners including FOXO1, NCOA1, NCOA2 and WWTR1. Although the differential diagnosis of BSNS is broad, careful morphologic inspection together with targeted ancillary studies is often sufficient to arrive at the correct diagnosis. As these tumors have significant local recurrence rates but lack metastatic potential, awareness and accurate diagnosis of this rare and newly described neoplasm is critical for appropriate management.

Imaging characteristics and clinical outcomes of biphenotypic sinonasal sarcoma

Objectives

Biphenotypic sinonasal sarcoma (BSS) is a new, rare tumor characterized by concomitant neural and myogenic differentiation. The aim of this study is to describe the imaging characteristics and clinical outcomes of this neoplasm.

Methods

A retrospective review of BSS patients surgically treated within a tertiary academic health care system was performed. Imaging characteristics and clinical outcomes were reviewed.

Results

Five patients underwent surgical resection of BSS tumors. Negative surgical margins were achieved in four (80%) patients. There were no deaths but two (40%) patients developed local recurrences during the postoperative follow‐up period (median follow‐up 31.4 months). Review of imaging characteristics revealed a median tumor size of 3.8 cm in greatest dimension. All tumors were unilateral and centered within the nasoethmoidal region. In all cases, the tumors extended to the nasal septum, lamina papyracea, and anterior skull base with variable degrees of erosion through these structures. On CT, involved bony structures demonstrated mixed lytic and sclerotic pattern, with definitive hyperostotic bone identified in four (80%) cases. On MRI, tumors were isointense‐to‐mixed iso/hypointense on both T1‐ and T2‐weighted sequences with one tumor demonstrating mixed T2 hyperintensity. All cases demonstrated gadolinium contrast enhancement.

Conclusions

BSS is a locally aggressive tumor with a low risk of regional or distant metastases but has a significant rate of recurrence even with adequate resection. Despite its rarity, BSS should be considered in the differential diagnosis when imaging demonstrates a unilateral nasoethmoidal mass that is predominantly isointense to cerebral gray matter on T2‐weighted MRI and is hyperostotic on CT.

Level of Evidence

4

Expression of PAX3 Distinguishes Biphenotypic Sinonasal Sarcoma From Histologic Mimics

Biphenotypic sinonasal sarcoma (BSNS) is a distinctive, anatomically restricted, low-grade spindle cell sarcoma that shows considerable histologic overlap with other cellular spindle cell neoplasms. This tumor type shows both myogenic and neural differentiation, which can be demonstrated by immunohistochemistry; however, the available diagnostic markers are relatively nonspecific. BSNS is characterized by PAX3 rearrangements, with MAML3 as the most common fusion partner. Our aim was to determine whether immunohistochemistry using a monoclonal PAX3 antibody could distinguish BSNS from potential histologic mimics, as well as to evaluate a widely available polyclonal PAX8 antibody, which is known to cross-react with other paired box transcription factor family members. Immunohistochemistry for PAX3 and PAX8 was performed on whole sections of 15 BSNS (10 with confirmed PAX3 rearrangement) and 10 cases each of the following histologic mimics: malignant peripheral nerve sheath tumor, monophasic synovial sarcoma, spindle cell rhabdomyosarcoma (RMS), solitary fibrous tumor, sinonasal hemangiopericytoma, and cellular schwannoma, as well as alveolar RMS (which harbors PAX3 or PAX7 gene rearrangements). BSNS showed consistent expression of PAX3 (15/15), all multifocal-to-diffuse and most with moderate-to-strong intensity of staining. One single case of spindle cell RMS showed PAX3 expression (1/10), and all other histologic mimics were completely PAX3-negative. In contrast, nuclear staining for PAX8 was present in all 15 BSNS, 7/10 malignant peripheral nerve sheath tumor, 3/10 cellular schwannomas, 2/10 sinonasal hemangiopericytomas, 1/10 synovial sarcoma, 1 spindle cell RMS, and 1 solitary fibrous tumor. All cases of alveolar RMS were positive for PAX8, and most were also positive for PAX3 (8/10). Immunohistochemical expression of PAX3 is highly sensitive (100%) and specific (98%) for BSNS. A polyclonal PAX8 antibody also stains BSNS (likely due to cross-reactivity with PAX3) but has much lower specificity (75%), with frequent expression in numerous mimics.

[Sinonasal tumors : News from the WHO with special reference to mesenchymal entities]

The last two decades have seen significant advances in the pathology of sinonasal tract neoplasms. This was the consequence of the availability of several innovative diagnostic tools, which resulted in a dynamic evolution of entities and splitting of newly defined or conceptualized entities and subtypes that have been included in the spectrum of old heterogeneous diseases. Most of these new tumor subtypes have distinctive demographic, clinicopathologic, and biological characteristics with prognostic and therapeutic implications for individual patients. NUT carcinoma (NUT midline carcinoma) was separated from the spectrum of sinonasal undifferentiated carcinoma (SNUC) and is defined by specific recurrent translocation. On the other hand, the recently described SMARCB1-deficient carcinoma (while probably representing a distinctive clinicopathologic entity) remained as a variant in the SNUC spectrum. A new neoplasm in the spectrum of non-keratinizing carcinomas is the human papillomavirus(HPV)-related adenoid-cystic-like sinonasal carcinoma with its distinctive, albeit diverse, morphology. In the group of small round-cell malignancies, adamantinoma-like Ewing sarcoma has been delineated as an important diagnostic pitfall given its prominent epithelial differentiation. Inclusion of the biphenotypic (myoneural) sinonasal sarcoma (BSS) as a low-grade malignancy defined by recurrent PAX3/MAML3-translocation represents an important feature of the new WHO classification given the distinctive biological behavior of this low-grade non-metastasizing rare entity, which has been uniformly misclassified as a peripheral nerve sheath tumor or leiomyosarcoma in the past. Recognition of CTNNB1 mutations and STAT6/NAB2 gene fusions as defining genetic markers for sinonasal hemangio‑/glomangiopericytoma and solitary fibrous tumors, respectively, represents another important achievement in recent years. This review summarizes the new aspects in the WHO classification and also addresses recently described entities that have not been included in the WHO classification.

Imaging Review of New and Emerging Sinonasal Tumors and Tumor-Like Entities from the Fourth Edition of the World Health Organization Classification of Head and Neck Tumors

The sinonasal tract is an environment diverse with neoplasia. Given the continued discovery of entities generally specific to the sinonasal tract, the fourth edition of the World Health Organization Classification of Head and Neck Tumors was released in 2017. It describes 3 new, well-defined entities and several less-defined, emerging entities. The new entities are seromucinous hamartomas, nuclear protein in testis carcinomas, and biphenotypic sinonasal sarcomas. Emerging entities include human papillomavirus-related sinonasal carcinomas, SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1-deficient sinonasal carcinomas, renal cell-like adenocarcinomas, and chondromesenchymal hamartomas. The literature thus far largely focuses on the pathology of these entities. Our goal in this report was to familiarize radiologists with these new diagnoses and to provide available information regarding their imaging appearances.

[Diagnostic challenge of biphenotypic sinonasal sarcoma]

Sinonasal biphenotypic sarcoma has recently been described and included in the 2017 WHO classification. It is a low-grade sarcoma which is characterized by PAX3 rearrangements. It remains a diagnostic challenge because of its scarcity, and its considerable histologic overlap with other cellular spindle cell neoplasms. The histologic features, the immunoprofile and the main differential diagnoses of sinonasal biphenotypic sarcoma are presented through a case.

An update on head and neck cancer: new entities and their histopathology, molecular background, treatment, and outcome

The head and neck region harbor numerous specialized tissues of all lineages giving rise to a plethora of different malignancies. In recent years, new types and subtypes of cancer has been described here due to the recognition of their histological and molecular characteristics. Some have been formally accepted in the most recent classifications from the World Health Organization (WHO) and American Joint Committee on Cancer (AJCC) as distinct diseases due to characteristics in clinical presentation, outcome, and treatment. In particular, this applies to malignancies of the salivary gland, sinonasal tract, and oropharynx. In this overview, we present the most recent developments in the classification, histopathological characteristics, and molecular features of head and neck cancer. The clinical and radiological characteristics, outcome, and treatment options including perspectives for targeted therapies, are discussed.

Recurrence of Biphenotypic Sinonasal Sarcoma With Cerebral Hemorrhaging

Biphenotypic sinonasal sarcoma (BSNS) is a newly classified tumor that is characterized by neural and myogenic differentiation. The authors herein report a rare patient of the recurrence of BSNS with intracranial hemorrhaging and a review of the literature. A 70-year-old man presented with disturbance of consciousness and vomiting blood. He had undergone resection of a sinonasal tumor 11 years earlier and shown no recurrence at his last follow-up 4 years ago. Computed tomography showed cerebral hemorrhaging around a low-density mass that occupied the left frontal base and left ethmoid sinus. Total resection was performed. A histological examination of tumor specimens obtained from the first and the second resections revealed almost the same characteristic morphological features and the patient was diagnosed with BSNS. The lesion was negative for any fusion genes, as previously reported. The long-term progression of BSNS is not clear. This case appears to be the first reported recurrence of BSNS with cerebral hemorrhaging. Biphenotypic sinonasal sarcoma should be considered to need long-term follow-up.

Sinonasal glomangiopericytoma: A clinicopathologic study

Sinonasal glomangiopericytoma (SNGP) is a neoplasm arising in the nasal cavity and paranasal sinuses that shows perivascular myoid differentiation. The diagnosis of SNGP may be diagnostically challenging due to a large number of potential mimics. In the present study, we sought to characterize the histological and molecular features of six cases of SNGP found in prior surgical pathology records over a 15-year period. The average age at diagnosis was 48.5 years (range: 31-78 years), and the male-to-female ratio was 1:1. Imaging studies in all six cases demonstrated avidly enhancing, lobulated soft tissue masses in the nasal cavity, extending into the sinuses and nasopharynx. Histologically, the tumors were unencapsulated and composed of a proliferation of closely packed, bland, and uniform spindle cells growing deep to an intact surface respiratory epithelium. The cells were separated by a distinctive vascular network ranging from capillaries to large vascular spaces. All cases demonstrated strong positivity for smooth muscle actin, cyclin D1, CD99, and β-catenin (100%). Targeted sequencing revealed recurrent CTNNB1 missense mutations in all cases tested. Additionally, TLE1 was positive in all cases which has not been previously reported. No tested cases harbored SS18 translocations. We found that while no single marker resolves immunohistochemical overlap between SNGP and its histologic mimics, an extended immunohistochemical panel that includes β-catenin, cyclin D1, STAT6, smooth muscle actin, pan-cytokeratin cocktails, S100, and SOX10 helps to support the diagnosis of SNGP in diagnostically challenging cases without the need for molecular studies.