Presentation of Rarely Occurring Inverted Squamous Papilloma of Nasal Cavity: A Case Report.

This report presents a case of a rarely occurring inverted squamous papilloma, which shows papillary proliferation in squamous epithelium. Inverted papillomas (IPs) are benign epithelial growths that occur in the underlying stroma of the nasal cavity and paranasal sinuses. While viral infections, allergies, and chronic sinusitis have all been proposed as potential causes, the pathophysiology of this lesion is still unknown. Most of the time, IP reflects residual disease, yet the recurrence rates are extremely high. A 60-year-old male patient has chief complaints of right-sided nasal congestion and excessive sneezing and discharge from the nose, which cause discomfort to the patient and make him unable to sleep at night. Computed tomography reveals both the enlargement of the osteomeatal complex and soft-tissue density opacification of the right side of the nasal cavity. The only way to diagnose this type of squamous papilloma is through histopathological examination. In this work, we evaluated the histological characteristics of sinonasal IP and presented a case report of an uncommon instance of inverted squamous papilloma of the nasal cavity.

Unveiling the Rarity: A Fascinating Case of Chondro-Osseous Respiratory Epithelial Adenomatoid Hamartoma (COREAH) in the Sinonasal Tract.

Chondro-osseous respiratory adenomatoid hamartoma (COREAH) are extremely rare benign lesions of the sinonasal tract. It is present in 3 to 83-year-olds. It originates from various sites of the sinonasal tract; the most common site is the posterior lateral wall of the nasal cavity. Imaging calcification is an important finding in COREAH. In this case report, we present an exceptionally rare occurrence involving a 55-year-old female patient who exhibited symptoms of nasal obstruction, bleeding from the left side of the nasal cavity and loss of smell. We aim to share our experience in managing this unique condition. Diagnostic nasal endoscopic examination of the patient revealed a reddish, fleshy polypoidal mass in the left nasal cavity arising from the lateral wall of the left nasal cavity posteriorly and extending anteriorly into the left nasal cavity. The patient underwent an excisional biopsy. Upon microscopic examination, we observed a hamartomatous proliferation of respiratory-type glands exhibiting mucinous metaplasia. Additionally, numerous spicules of mature bone were present, a distinctive feature of COREAH. The patient underwent a 6-month follow-up, during which no recurrent growth was detected within the nasal cavity.

Angioleiomyoma of the Sinonasal Tract: A Systematic Review of an Uncommon Clinicopathological Entity.

Introduction Angioleiomyoma is a rare neoplasm that represents ∼ 0.2 % of all head and neck benign tumors and ∼ 2% of total cases of tumors of the sinonasal tract. It was once considered a possible subtype of leiomyoma, but, in the 2020 World Health Organization (WHO) classification of soft tissue tumors, it is accepted as a singular entity. Objective To systematically review the existing literature on angioleiomyoma in the light of the new classification of soft tissue tumors. Data Synthesis The present study was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A comprehensive search in the PubMed, Cochrane, Scopus, and Google Scholar databases was performed in January 2022. The search items included the following keywords: nasal angioleiomyoma OR sinonasal angioleiomyoma OR nasal vascular leiomyoma OR sinonasal vascular leiomyoma . A total of 87 patients were evaluated. He age of the patients in the studies ranged from 15 to 88 years (mean age at diagnosis: 55.6 years). The most common site of involvement was the nasal septum (28.4 %), followed by the inferior turbinate (22.5%). The most common symptom was nasal obstruction (66.7%), followed by epistaxis (47.1%). Surgical excision represented the main treatment, and there was recurrence of pathology in only 1 case (0.9%). Conclusion To our knowledge, only 87 cases of sinonasal-tract angioleiomyoma have been previously described. The results of the present review seem to confirm the rarity and the benign nature of this neoplasm, and they seem to confirm the necessity to improve the available data about sinonasal-tract angioleiomyoma.

Schwannoma of Nasopharynx-A Rare Case with A Complex Presentation.

Nasopharyngeal tumors are rare, and schwannomas originating from this location are extremely uncommon. Schwannomas are tumors arising from the Schwann cells of peripheral nerve sheath which are neuroectodermal in origin. These are benign, slow growing, well-encapsulated tumors and are mostly seen in the head and neck region. We present a rare case of schwannoma with nasopharynx as its epicenter in an elderly female patient who presented with complaints of hematemesis, bilateral nasal obstruction and stertorous breathing. Diagnostic nasal endoscopy revealed a smooth mucosa covered globular mass occupying bilateral choana. Contrast-enhanced computed tomography of Nose and paranasal sinuses revealed a homogenous mass occupying the entire nasopharynx extending into the nasal and oropharyngeal cavities. The patient underwent Trans-nasal Endoscopic excision under general anesthesia. Nasopharyngeal tumors have a wide range of presentation and a high index of clinical suspicion combined with imaging modalities is required for diagnosis and pre operative planning. Some tumors can cause life-threatening airway obstruction due to delayed presentation and should be managed efficiently and meticulously, with endoscopic excision being a viable approach for cases confined within the nasopharynx.

Re-evaluating a historic cohort of sinonasal and skull base mucoepidermoid carcinoma: an institutional experience.

AIMS: Primary mucoepidermoid carcinomas (MECs) of the sinonasal tract and nasopharynx are rare entities that represent a diagnostic challenge, especially in biopsy samples. Herein, we present a case series of MECs of the sinonasal and skull base and its mimics to evaluate the clinicopathological and molecular characteristics in order to avoid misdiagnosis. METHODS: We reviewed the pathology records of patients diagnosed from 2014 to 2022. Thirty MECs were consecutively diagnosed during that period. RESULTS: Based on morphological and fluorescence in situ hybridization (FISH) analyses, 30 tumors originally diagnosed as MECs were separated into MAML2 fusion-positive (7 cases) and MAML2 fusion-negative groups (23 cases), in which 14 tumors were positive for the EWSR1::ATF1 fusion; these tumors were reclassified to have hyalinizing clear cell carcinoma (HCCC). The remaining nine MAML2 FISH negative cases were reconfirmed as squamous cell carcinoma (SCC, 3 cases) which showed keratinization and high Ki-67 expression; DEK::AFF2 carcinomas (2 cases), in which DEK gene rearrangement was detected by FISH; and MECs as previously described (4 cases) with typical morphological features. Including 7 MAML2 rearrangements tumors, 11 MEC cases had a male-to-female ratio of 4.5:1, and 6 tumors arose from the nasopharyngeal region, while 5 tumors arose from the sinonasal region. The prognosis of this series of salivary gland-type MECs was favorable. CONCLUSIONS: Our study confirmed that HCCC runs the risk of being misdiagnosed as MEC in the sinonasal tract and nasopharynx, particularly with biopsy specimens. Careful histological evaluation with supporting molecular testing can facilitate pathological diagnoses.

Patterns of recurrence and disease progression in patients with positive-margin olfactory neuroblastoma following primary resection.

OBJECTIVE: Olfactory neuroblastoma (ONB) is a rare, malignant tumor of the sinonasal tract that arises from olfactory epithelium. Although surgery is the preferred first-line treatment, tumor involvement of adjacent structures may preclude the ability to achieve negative margins during initial resection. Herein, the authors examine the oncological outcomes of patients with positive margins after primary resection of ONB, with the aim of determining predictors of disease progression and patterns of recurrence. METHODS: The authors performed an institutional review of 25 patients with positive-margin ONB after resection. Cox survival analyses were used to determine any statistically significant predictors of worse progression-free survival (PFS) and overall survival (OS). RESULTS: A total of 93 patients who were diagnosed with ONB were identified, of whom 25 patients had positive margins following their primary resection. Eleven (44%) had a delayed finding of positive margins that were initially negative in the operating room but returned as positive on final pathology. Four patients had subtotal resection (STR), whereas the remaining patients underwent gross-total resection. Twenty-four patients received adjuvant radiotherapy (96%), and 15 additionally received adjuvant chemotherapy (60%). Fourteen patients (56%) experienced recurrence/progression at a median time of 35 months following resection (IQR 19-70 months). Local recurrence occurred in 10 patients (40%), regional in 9 (36%), and distant metastasis in 2 (8%). In Cox survival analyses, the 5-year PFS and OS were 55.1% and 79.2%, respectively. Kadish stage D was predictive of worse PFS in univariate (hazard ratio [HR] 15.67, 95% CI 3.38-72.61, p < 0.001) and multivariate (HR 15.46, 95% CI 1.45-164.91, p = 0.023) analyses. Hyams grade, adjuvant chemotherapy, and primary radiotherapy were not associated with PFS. Furthermore, Kadish stage D and STR were predictive of worse OS in univariate analysis (HR 12.64, 95% CI 2.03-78.86, p = 0.007; HR 7.31, 95% CI 1.45-36.84, p = 0.016; respectively). However, local and regional recurrence was not associated with worse OS. CONCLUSIONS: Approximately half of patients with positive-margin ONB may experience disease recurrence. Patients with an advanced disease stage (Kadish D) may have a higher likelihood of developing recurrence/progression. Furthermore, patients with tumor burden following resection (STR and Kadish D) may have worse OS. However, in positive-margin ONB with no gross disease following initial resection, the presence of disease recurrence does not significantly alter survival when receiving salvage therapy.

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.

What is the rate of occult nodal metastasis in squamous cell carcinomas of the sinonasal tract? A systematic review.

OBJECTIVE: The role of elective neck dissection (END) in the management of clinical N0 (cN0) squamous cell carcinomas (SCC) of the sinonasal tract is unclear. In this systematic review, we evaluate the risk of occult nodal metastasis in sinonasal SCCs with cN0M0 tumors to support clinical decision making. METHODS: A literature search was conducted in the following three electronic databases: Medline/PubMed, ScienceDirect, and Google Scholar. Articles were assessed for eligibility in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Two independent authors extracted the data. The Methodological Items for Non-Randomized Studies (MINORS) tool was used for the assessment of biases of each included study. RESULTS: Our systematic review included six studies that met the inclusion criteria, all retrospective in design. The rate of histologically proven metastasis of sinonasal SCC to the clinically negative neck is 12.5%. Almost half of the positive cases are pathologically staged as N2 (6.5%). CONCLUSION: Our systematic review provides the rate of sinonasal SCC occult metastasis to the neck so that the surgeons can discuss with patients the risks and possible merits of adding an elective neck management in the surgical plan.

Angioleiomyoma of the Sinonasal Tract: A Systematic Review of an Uncommon Clinicopathological Entity

Abstract Introduction Angioleiomyoma is a rare neoplasm that represents ∼ 0.2 % of all head and neck benign tumors and ∼ 2% of total cases of tumors of the sinonasal tract. It was once considered a possible subtype of leiomyoma, but, in the 2020 World Health Organization (WHO) classification of soft tissue tumors, it is accepted as a singular entity. Objective To systematically review the existing literature on angioleiomyoma in the light of the new classification of soft tissue tumors. Data Synthesis The present study was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A comprehensive search in the PubMed, Cochrane, Scopus, and Google Scholar databases was performed in January 2022. The search items included the following keywords: nasal angioleiomyoma OR sinonasal angioleiomyoma OR nasal vascular leiomyoma OR sinonasal vascular leiomyoma. A total of 87 patients were evaluated. He age of the patients in the studies ranged from 15 to 88 years (mean age at diagnosis: 55.6 years). The most common site of involvement was the nasal septum (28.4 %), followed by the inferior turbinate (22.5%). The most common symptom was nasal obstruction (66.7%), followed by epistaxis (47.1%). Surgical excision represented the main treatment, and there was recurrence of pathology in only 1 case (0.9%). Conclusion To our knowledge, only 87 cases of sinonasal-tract angioleiomyoma have been previously described. The results of the present review seem to confirm the rarity and the benign nature of this neoplasm, and they seem to confirm the necessity to improve the available data about sinonasal-tract angioleiomyoma.

EWSR1::POU2AF3(COLCA2) Sarcoma: An Aggressive, Polyphenotypic Sarcoma With a Head and Neck Predilection.

EWSR1::POU2AF3 (COLCA2) sarcomas are a recently identified group of undifferentiated round/spindle cell neoplasms with a predilection for the head and neck region. Herein, we report our experience with 8 cases, occurring in 5 men and 3 women (age range, 37-74 years; median, 60 years). Tumors involved the head/neck (4 cases), and one each the thigh, thoracic wall, fibula, and lung. Seven patients received multimodal therapy; 1 patient was treated only with surgery. Clinical follow-up (8 patients; range, 4-122 months; median, 32 months) showed 5 patients with metastases (often multifocal, with a latency ranging from 7 to 119 months), and 3 of them also with local recurrence. The median local recurrence-free and metastasis-free survival rates were 24 months and 29 months, respectively. Of the 8 patients, 1 died of an unknown cause, 4 were alive with metastatic disease, 1 was alive with unresectable local disease, and 2 were without disease. The tumors were composed of 2 morphologic subgroups: (1) relatively bland tumors consisting of spindled to stellate cells with varying cellularity and fibromyxoid stroma (2 cases) and (2) overtly malignant tumors composed of nests of "neuroendocrine-appearing" round cells surrounded by spindled cells (6 cases). Individual cases in the second group showed glandular, osteogenic, or rhabdomyoblastic differentiation. Immunohistochemical results included CD56 (4/4 cases), GFAP (5/8), SATB2 (4/6), keratin (AE1/AE3) (5/8), and S100 protein (4/7). RNA sequencing identified EWSR1::POU2AF3 gene fusion in all cases. EWSR1 gene rearrangement was confirmed by fluorescence in situ hybridization in 5 cases. Our findings confirm the head/neck predilection and aggressive clinical behavior of EWSR1::POU2AF3 sarcomas and widen the morphologic spectrum of these rare lesions to include relatively bland spindle cell tumors and tumors with divergent differentiation.

Application Of New WHO Classification On Malignancies Of Sinonasal Tract: Correlation With Epidemiology And Survival In Pakistani Population.

Objectives: To analyse the clinicopathological characteristics of sinonasal malignancies in the light of the updates regarding head and neck tumours. METHODS: The retrospective study was conducted at the Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, Pakistan, and comprised data of patients diagnosed with primary malignant tumours of the sinonasal tract between 2015 and 2020. Slides related to biopsies and resection specimens were retrieved from the institutional database and reviewed by two pathologists. Follow-up data was also obtained. Data was analysed using SPSS 20. RESULTS: Of the 245 samples, 144(58.7%) were epithelial tumours, 46(18.7%) neuroectodermal tumours, 41(16.7%) haematolymphoid tumours and 14(5.7%) were malignant soft tissue tumours. A heavy reliance was placed on immunohistochemical stains to diagnose poorly-differentiated tumours. Survival was dismal, especially with early and frequent spread to the brain (33.3% in cases of Sinonasal Undifferentiated Carcinoma). CONCLUSIONS: A wide array of sinonasal malignancies was seen. Updated knowledge of the malignancies prevalent in the region is imperative for timely diagnosis and treatment.

Clinical outcomes of head and neck mucosal melanoma treated with surgery: a single-center study in Japan.

BACKGROUND: Head and neck mucosal melanomas are rare malignancies. Although the prognosis is poor owing to the high incidence of distant metastases, locoregional control remains important. It is difficult to obtain results in a large cohort because of its rarity. This study aimed to elucidate the survival outcomes of patients with head and neck mucosal melanoma treated with surgery in Japan. METHODS: Patients with head and neck mucosal melanoma who were surgically treated between 2007 and 2021 at the National Cancer Center Hospital were retrospectively analyzed. RESULTS: A total of 47 patients were included in this study. The 5-year overall survival, disease-specific survival, locoregional control and relapse-free survival rates were 42%, 50%, 79% and 13%, respectively. The disease-specific survival of the oral mucosal melanoma group was significantly better than that of the sinonasal mucosal melanoma group (5-year disease-specific survival rate: 70% versus 37%, respectively; P = 0.04). Multivariate analyses revealed that sinonasal mucosal melanoma were independently significant adverse prognostic factor, for overall survival and disease-specific survival. Patients with oral mucosal melanoma patients had a higher incidence of lymph node metastasis than those with sinonasal mucosal melanoma patients (P < 0.0001). CONCLUSION: This study demonstrated the survival outcomes of the largest cohort of patients with head and neck mucosal melanomas treated surgically at a single institution within the past 20 years in Japan. We found that survival outcomes and incidence of nodal metastases varied by site.

Association Between 18F-Fluorodeoxyglucose Uptake and Mutation Status of Epidermal Growth Factor Receptor in Sinonasal Tract Cancer.

BACKGROUND/AIM: The Warburg effect of cancer has been applied to detect various carcinomas though the 18F-fluorodeoxyglucose (18F-FDG) uptake on positron emission tomography with computed tomography (PET/CT). 18F-FDG-PET/CT in lung cancer predicted the mutation status of epidermoid growth factor receptor (EGFR). This study aimed to investigate whether 18F-FDG uptake parameters were significantly related to EGFR mutation status in patients with sinonasal tract squamous cell carcinoma (STSCC). PATIENTS AND METHODS: Twenty-nine tumor specimens of primary STSCC from patients with definitive treatment were collected. RESULTS: The 18F-FDG uptake from primary tumors was not different between mutant- and wild-status of EGFR on either Mann-Whitney U-test or the receiver operating curve. A metabolic tumor volume of ≥25 with the minimum p-value from the log-rank test for STSCC-specific survival was associated with a significantly shorter STSCC-specific, disease-free, local recurrence-free survival on the univariate and multivariate analyses adjusted for the clinical stage, treatment, and EGFR status. CONCLUSION: 18F-FDG-PET/CT did not predict mutation of the EGFR status in STSCC.

MRI features of sinonasal tract angiofibroma/juvenile nasopharyngeal angiofibroma: Case series and systematic review.

BACKGROUND AND PURPOSE: To comprehensively summarize the radiological characteristics of sinonasal tract angiofibroma (STA) (commonly known as juvenile nasopharyngeal angiofibroma). METHODS: Forty-four lesions from 41 cases provided by 33 study articles identified through a systematic review and 13 lesions from 13 cases from our institution associated with patients with STA who underwent MRI were included in the review study, carried out by two board-certified experienced radiologists. RESULTS: The study participants were all male patients with a mean age of 15.6 years at the time of diagnosis. All of them presented with nasal cavity lesions (100%), predominantly in the nasopharynx (98.2%). The sphenopalatine foramen/pterygopalatine fossa was involved in 76.0%, and compressive shift of the posterolateral wall of the maxillary sinus was present in more than half (57.9%). T2-weighted imaging signal intensity was heterogeneous with mixed high and iso intensities as compared to skeletal muscle (100%). T1-weighted imaging showed partial high signal intensity in 61.1% of the cases. Flow void and intense enhancement were present in almost all cases. Cystic/nonenhancement changes on contrast-enhanced MRI were relatively common (40.8%). The mean apparent diffusion coefficient value (2.07 × 10-3  mm2 /second) and some quantitative dynamic contrast-enhanced MRI parameters were high. There was a significant difference in the frequency of residual/recurrent lesions based on the presence of MRI findings of skull base invasion (p = .017) and intracranial extension (p = .003). CONCLUSIONS: We summarized the MRI findings of STA that can facilitate timely diagnosis and appropriate management.

Salivary Duct Carcinoma Originated from the Inferior Turbinate: A Rare Case Report.

Salivary duct carcinoma (SDC) is an uncommon but highly aggressive tumor with a poor prognosis. SDC mainly arises from the major salivary glands, typically the parotid gland. Here, we report a rare case of sinonasal SDC in a 54-year-old male patient that might have originated from the inferior turbinate. The patient presented with left nasal congestion and rhinorrhea. Following an endoscopic intervention, the histopathological examination revealed a diagnosis of SDC, characterized by the formation of solid cancer nests and central comedo-type necrosis. Given the highly aggressive nature and unfavorable prognosis of SDC, it is essential to consider it as a differential diagnosis for unilateral nasal tumors.

Low-grade papillary Schneiderian carcinoma with TP53 mutation: a case report and review of the literature.

BACKGROUND: Low-grade papillary Schneiderian carcinoma (LGPSC) is a relatively new entity of the sinonasal tract and is characterized by a bland morphology simulating sinonasal papilloma, invasive growth pattern with pushing borders, and aggressive clinical behavior with multiple recurrences and metastatic potential. Recently, DEK::AFF2 fusions were identified in LGPSC. However, some LPGSCs lack DEK::AFF2 fusion, and the molecular features of these tumors have not been clarified. CASE PRESENTATION: A 69-year-old man presented with a discharge of pus from his left cheek. Computed tomography revealed a mass involving the left maxillary sinus, ethmoid sinus, and nasal cavity with the destruction of the orbital wall. The biopsy specimens showed that the tumor had a predominantly exophytic, papillary growth and did not have an apparent stromal invasion. The tumor was composed of multilayered epithelium that showed bland morphology with a round to polygonal shape, abundant eosinophilic cytoplasm, and uniform nuclei. Dense neutrophilic infiltrates were focally present. Immunohistochemically, CK5/6 was strongly and diffusely positive, and p16 was negative. p63 was mainly positive in the basal layer, and EMA was predominantly expressed in the outermost cell layer. DNA-based targeted sequencing showed TP53 R175H mutation, whereas neither EGFR nor KRAS mutation was identified. Reverse transcription polymerase chain reaction and fluorescence in situ hybridization revealed no DEK::AFF2 fusion. CONCLUSIONS: We describe the first case of TP53-mutant LGPSC and review the literature. LGPSC is a genetically heterogeneous entity, and the recognition of this rare entity and comprehensive assessment of clinicopathological and molecular findings are crucial for the correct pathological diagnosis and clinical management.

A Report of Two Cases of Malignant Tumor of the Maxillary Sinus Diagnosed Using Fine-Needle Aspiration Cytology.

Primary and metastatic malignancies arising in the sinuses are rare and histologically diverse. The role of fine-needle aspiration cytology (FNAC) and the cytomorphologic characteristics of these tumors have not been specifically addressed. We described two cases of suspected malignant maxillary sinus tumors in 85- and 90-year-old patients with comorbid conditions, both of whom underwent tissue biopsies that failed to yield a definitive diagnosis. We performed FNAC after imaging confirmed that the malignant tumors were outside the maxillary sinus. The 85- and 90-year-old patients were diagnosed with squamous cell carcinoma (SCC) and adenocarcinoma, respectively. In the latter, the cell block method was used to prepare the specimen, rendering individual cells identifiable. Atypia of the histological structure was confirmed without the influence of cell duplication, a known weakness of FNAC. Thus, the diagnosis was made quickly. We believe that FNAC would be utilized more frequently for the definitive diagnosis of sinonasal tumors as the technique and diagnostic technology improve further.

A Low-grade Sinonasal Sarcoma Harboring EWSR1::BEND2: Expanding the Differential Diagnosis of Sinonasal Spindle Cell Neoplasms.

BACKGROUND: Molecular diagnostics has greatly refined sinonasal tumor pathology over the past decade. While much of the attention has focused on carcinomas, it is becoming clear that there are emerging mesenchymal neoplasms which have previously defied classification. METHODS: Here, we present a 33-year-old woman with a multiply recurrent sinonasal spindle cell tumor exhibiting distinctive features, and not easily classifiable into a specific category. RESULTS: The hypercellular tumor was composed of plump spindled cells, with uniform vesicular chromatin arranged as vague fascicles around a prominent hemangiopericytoma-like vasculature. The mitotic rate was brisk at 10 per 10 high power fields. By immunohistochemistry, it was only positive for EMA (focal) and SATB2 (diffuse, weak). Fusion analysis uncovered EWSR1::BEND2, a fusion which is best known for being seen in astroblastoma, but which has not yet been reported in sarcomas. CONCLUSION: This case underscores the utility of fusion analysis when confronted with a sinonasal spindle cell neoplasm which does not neatly fit into any specific category. It remains to be seen if EWSR1::BEND2 sinonasal sarcoma represents a distinct entity.

Desmoplastic Small Round Cell Tumor of the Head and Neck: A Potential Diagnostic Pitfall.

Primary desmoplastic small round cell tumor (DSRCT) in the head and neck region is extremely rare. There is limited information about its clinicopathological characteristics, prognosis, and treatment modalities. The purpose of this study is to provide a comprehensive review of DSRCT occurring primarily in the head and neck, to demonstrate its peculiar morphology and immunohistochemical expression, and to address the differential diagnoses. A total of 25 cases were collected after a thorough review of the relevant literature. DSRCT was most frequently reported in the major salivary glands, followed by the eyes. Furthermore, some cases were misinterpreted as poorly differentiated carcinoma, Ewing sarcoma, and olfactory neuroblastoma. Diagnosing DSRCTs in the head and neck can be very challenging due to their rarity in this location, overlapping morphology, and immunohistochemistry. In these cases, following a systemic approach helps to solve diagnostic problems.

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.