Reappraisal of sinonasal undifferentiated carcinoma: SMARCB1 (INI1)-deficient sinonasal carcinoma: a single-institution experience

Clinicopathologic and Molecular Characterization of SMARCB1-Deificient Sinonasal Carcinomas -A Systematic Study from a Single Institution Cohort

BACKGROUND

SMARCB1-deficient and SMARCA4-deficient sinonasal carcinomas are rare, with only a few systematic studies available in the literature. Secondary EWSR1 gene abnormalities have been reported in SMARCB1-deficient tumors. This study aimed to systematically investigate SWI/SNF complex-deficient sinonasal carcinomas in a single-institution cohort, perform clinicopathologic characterization, and explore the underlying molecular mechanisms.

METHOD

Immunohistochemistry (IHC) of INI1 and BRG1 was performed on tissue microarrays containing tumor tissue from 149 consecutive sinonasal carcinomas. Single nucleotide polymorphism (SNP) array and EWSR1 gene fluorescence in situ hybridization (FISH) analyses were conducted on SMARCB1-deficient sinonasal carcinomas. Clinicopathologic characterization was studied.

RESULT

Of the 149 sinonasal carcinomas, 7 (4.7%) showed SMARCB1 loss, while none demonstrated SMARCA4 loss. All patients were male and presented with advanced-stage tumors. Four SMARCB1-deficient sinonasal carcinomas exhibited basaloid morphology, two displayed eosinophilic tumor morphology, and one had mixed morphology. Homozygous and heterozygous SMARCB1 deletions were identified in 4/6 and 2/6 cases respectively. Heterozygous loss involving genes neighboring SMARCB1 gene, including EWSR1, was observed in four cases. One tumor showed a heterozygous loss of the entire chromosome 22q. EWSR1 FISH assay revealed concordant heterozygous EWSR1 loss in these five cases.

CONCLUSION

SMARCB1-deficient carcinomas account for 4.7% of sinonasal carcinomas in this single-institution cohort, while SMARCA4-deficient tumors are even rarer, with none identified. SMARCB1-deficient sinonasal carcinomas exhibit a broad spectrum of morphologic and immunohistochemical features. These carcinomas show complex genetic alterations, with homozygous SMARCB1 deletions present in the majority of cases.

SMARCB1-deficient Sinonasal Carcinoma: Expanding the Pathologic Spectrum With a Series of 32 Cases

SMARCB1-deficient sinonasal carcinoma (SDSC) is a recently recognized rare malignancy. Despite growing awareness, SDSC remains susceptible to misdiagnosis owing to its rarity and overlapping features with diverse mimics. A retrospective review of the clinical and pathologic features of 32 SDSC including 4 SMARCB-1 deficient adenocarcinoma (SDAC) cases was performed. The patients were aged 19 to 76 years with a male predominance. Most tumors arose in the naso-ethmoid (75%), and advanced stage (93.6%), with frequent multi-sinus (90.5%) involvement. Histologically, tumors exhibited diverse morphologies, including basaloid (50%), rhabdoid (25%), and undifferentiated (12.5%) types. SDAC cases showed glandular differentiation with intraluminal and stromal mucin. Empty vacuoles (62.5%), pagetoid spread (31.3%), eosinophilic-granular bodies (18.8%), hyaline globules (15.2%), and florid glomeruloid neovascularization (15.6%) were additional findings. Yolk sac-like areas were encountered in 18.6%. Immunohistochemically, tumors were defined by a complete loss of SMARCB1 (100%); a variable reactivity for p40 (65.6%), synaptophysin (13.6%), glypican3 (6.1%), and CD34 (6.1%) was present. Notably, >90% of our patients had different initial diagnoses before referral. Lymph node metastasis, locoregional recurrence, and distant metastasis were seen in 23.3%, 24.1%, and 27.6% patients, respectively; 37.9% died of disease. In conclusion, SDSCs are rare and aggressive sinonasal malignancies that display a wide histologic spectrum including glandular differentiation. This study expands on the morphologic spectrum of SDSC by analyzing a large cohort of 32 cases, adding comprehensive clinical, histopathologic, and immunohistochemical data, and highlighting features to improve diagnostic accuracy. The emergence of targeted therapies, such as EZH2 inhibitors, further underscores the importance of accurate diagnosis.

SMARCB1 (INI-1)-Deficient Sinonasal Carcinoma: A Case Report and Literature Review

Background: SWItch/Sucrose Non-Fermentable related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1)-deficient sinonasal carcinoma (SDSC) is a malignant tumor classified as sinonasal undifferentiated carcinoma (SNUC). Purpose: Owing to the high aggressiveness and poor prognosis reported in recent literature, patients diagnosed with SNUC should consider further immunohistochemical examination to screen for SDSC. Timely diagnosis is critical and will contribute to follow-up targeted therapy and improved patient prognosis. Research Design: Case report. Study Sample: A case of SDSC with a history of chronic sinusitis with nasal polyps (CRSwNP). Data Collection: We collected all the clinical data of this patient. Results: The patient underwent planned functional endoscopic sinus surgery (FESS) and received chemotherapy combined with immunotherapy postoperatively. There was no evidence of recurrence or metastasis at the 3-month follow-up. Conclusions: The patient in this case presented with right intermittent epistaxis, and surgical histopathological examination confirmed a diagnosis of right SDSC and left CRSwNP. No related research has been reported.

Outcomes of SWI/SNF complex-deficient sinonasal carcinomas in a Southeast Asian cohort

BACKGROUND

SWI/SNF complex-deficient sinonasal carcinomas are rare, genetically distinct, and aggressive entities.

METHODS

SMARCB1 and SMARCA4 immunohistochemistry was retrospectively performed on a cohort of undifferentiated, poorly differentiated, and poorly defined sinonasal carcinomas. Survival outcomes were compared between SMARCB1/SMARCA4 (SWI/SNF complex)-deficient and -retained groups.

RESULTS

Eight SWI/SNF complex-deficient (six SMARCB1-deficient, two SMARCA4-deficient) cases were identified among 47 patients over 12 years. Triple-modality treatment was more frequently utilized in SWI/SNF complex-deficient carcinomas than in SWI/SNF complex-retained carcinomas (71.4% vs. 11.8%, p = 0.001). After a median follow-up of 21.3 (IQR 9.9-56.0) months, SWI/SNF complex-deficient sinonasal carcinomas showed comparable recurrence rates (57.1% vs. 52.9%, p = 0.839), time-to-recurrence (7.3 [IQR 6.6-8.3] vs. 9.1 [IQR 3.9-17.4] months, p = 0.531), and overall survival (17.7 [IQR 11.8-67.0] vs. 21.6 [IQR 8.9-56.0] months, p = 0.835) compared to SWI/SNF complex-retained sinonasal carcinomas.

CONCLUSION

Triple-modality treatment may improve survival in SWI/SNF complex-deficient sinonasal carcinomas.

Adaptive Treatment Strategy: Adjuvant Chemoradiotherapy for a Complex SMARCB1 (INI-1)-Deficient Sinonasal Carcinoma With Intracranial Extension

SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1) (integrase interactor 1)-deficient sinonasal carcinoma (SDSNC) is a rare and aggressive malignancy of the head and neck. It is characterised by the absence of nuclear SMARCB1 expression and typically presents at advanced stages due to non-specific symptoms resembling benign conditions such as nasal polyps or sinusitis. This report describes a 64-year-old male who presented with a sphenoidal sinus mass causing bony erosion and intracranial extension, associated with headaches and diplopia. Initial management included endoscopic debulking surgery, followed by chemoradiotherapy to address residual disease in proximity to the optic chiasm and brainstem. Urgent radiotherapy was delivered using volumetric-modulated arc therapy, with a total dose of 66 Gy, requiring precise sparing of critical structures. Immunohistochemical analysis confirmed SMARCB1 deficiency. Post-treatment imaging revealed significant tumour volume reduction, and immune checkpoint inhibitor therapy was initiated for disease control. At five months post-treatment, the tumour remained stable. This case highlights the diagnostic and therapeutic challenges of SDSNC, particularly in cases involving critical anatomic structures. It demonstrates the importance of multidisciplinary treatment strategies, advanced radiotherapy planning, and immunotherapy in optimising outcomes for this rare malignancy.

Outcomes of SMARCB1-deficient sinonasal carcinoma: Largest single-center cross-sectional study

BACKGROUND

We evaluate outcomes of SMARCB1-deficient sinonasal carcinomas in the largest single-institution study.

METHODS

Retrospective cross-sectional study of patients with SMARCB1-deficient sinonasal carcinoma between 1998 and 2024. Disease-specific survival (DSS) and recurrence-free probability (RFP) at 1 and 5 years were measured by Kaplan-Meier method.

RESULTS

There were 47 patients with a median age of 53. Initial pathological diagnosis was altered in 33%. Twelve (34%) patients received neoadjuvant chemotherapy, with one partial response. Curative surgical approach was undertaken in 73%. Definitive chemoradiation was administered in 20%. DSS at 1 and 5 years was 93% and 45%, respectively. RFP at 1 and 5 years was 73% and 33%, respectively. On multivariate analysis, cranial nerve involvement (p = 0.01 for DSS) remained significantly worse for DSS and overall survival.

CONCLUSIONS

SMARCB1-deficient tumors had limited response to neoadjuvant chemotherapy. Cranial nerve involvement was associated with worse prognosis. Optimal treatment is unclear. Surgery should be offered to patients with resectable disease.

SWI/SNF-Related Matrix-Associated Actin-Dependent Regulator of Chromatin Subfamily B Member 1 (SMARCB1)-Deficient Tumor in the Parapharyngeal Space: A Case Report

SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1) is a tumor suppressor gene, and SMARCB1 deficits have been associated with numerous malignant tumors. Carcinomas with a SMARCB1 deficit generally have a poor prognosis. In the head and neck region, there have been many recent cases of SMARCB1-deficient sinonasal carcinoma, but reports of extrasinonasal sites are extremely rare. This study reports a case of SMARCB1-deficient tumor in the right parapharyngeal space. A 64-year-old woman with right neck swelling was presented to our hospital, and imaging revealed a tumor in the right parapharyngeal space. After four years of follow-up, the tumor had increased in size, and a biopsy revealed deficits in SMARCB1 in the tumor cells. No definitive histological diagnoses were made. Radiation reduced the size of the tumor, and the patient survived without progression, three years after completion of treatment.

A Case of SMARCB1-Deficient Sinonasal Carcinoma With Clear Cell Morphology

SMARCB1 is a gene known to cause carcinogenesis in many soft tissue tumors, including malignant rhabdoid tumors and epithelioid sarcoma. Since the first report of a subtype of sinonasal carcinoma characterized by a deficiency of the SMARCB1 gene in 2014 to date, fewer than 200 cases have been reported. We report a case of SMARCB1-deficient sinonasal carcinoma with clear cell morphology. In our case, there are no evident basaloid or plasmacytoid/rhabdoid tumor cells, which are typical histopathological features of SMARCB1-deficient sinonasal carcinoma. SMARCB1-deficient sinonasal carcinoma is prone to recurrence and has a very poor prognosis. As the development of molecularly targeted agents progresses, therapeutic efficacy is expected to improve. Simultaneously, the importance of early and accurate diagnosis of SMARCB1-deficient sinonasal carcinoma will increase. With the limited information provided by biopsy specimens, it is necessary to confirm the loss of SMARCB1 expression by immunohistochemistry and investigate the presence of SMARCB1 gene deletion by molecular genetics, considering the possibility of SMARCB1-deficient sinonasal carcinoma even in atypical cases without basaloid or plasmacytoid/rhabdoid cell morphology, as in our case.

SWI/SNF-deficient Sinonasal Carcinomas

The classification of poorly differentiated sinonasal carcinomas and their nonepithelial mimics has experienced tremendous developments during the last 2 decades. These recent developments paved the way for an increasingly adopted approach to a molecular-based or etiology-based refined classification of the many carcinoma variants that have been historically lumped into the sinonasal undifferentiated carcinoma category. Among these new achievements, recognition of carcinoma subtypes driven by defects in the Switch/Sucrose nonfermentable (SWI/SNF) chromatin remodeling complex represents a major highlight. This resulted in a new definition of 4 sinonasal entities driven solely or predominantly by Switch/Sucrose nonfermentable complex deficiency: (1) SMARCB1(INI1)-deficient sinonasal carcinoma (lacking gland formation and frequently displaying a non-descript basaloid, and less frequently eosinophilic/oncocytoid morphology, but no features of other definable subtypes), (2) SMARCB1-deficient sinonasal adenocarcinoma (with unequivocal glands or yolk sac-like pattern), (3) SMARCA4-deficient undifferentiated (sinonasal undifferentiated carcinoma-like) carcinoma (lacking glandular or squamous immunophenotypes), and (4) SMARCA4-deficient subset (~80%) of sinonasal teratocarcinosarcoma. Fortunately, diagnostic loss of all these proteins can be detected by routine immunohistochemistry, so that genetic testing is not mandatory in routine practice. This review summarizes the main demographic, clinicopathological, and molecular features of these new entities.

Yolk sac tumor of postpubertal-type does not exhibit immunohistochemical loss of SMARCB1/INI1 and SMARCA4/BRG1…but choriocarcinoma?

The recently described SWI/SNF complex-deficient sinonasal carcinoma (SMARCB1 & SMARCA4) may exhibit a yolk sac-like morphology. Tumors with similar features (yolk sac-like histology combined with the immunohistochemical loss of SMARCB1/INI1 and/or SMARCA4/BRG1) have also been described in other sites, such as the female genital tract. In this study, we immunohistochemically assessed SMARCB1/INI1 and SMARCA4/BRG1 expression to evaluate if these proteins could be involved in the pathogenesis of testicular yolk sac tumors of postpubertal type (YSTpt). Specifically, we analyzed a retrospective case series comprising pure YSTpt and mixed germ cell tumors of the testis (GCTT) with YSTpt components. In the present study, no testicular YSTpt showed loss of SMARCB1/INI1 (0/24, 0%) or SMARCA4/BRG1 (0/24, 0%). However, testicular choriocarcinoma (CHC) and isolated syncytiotrophoblast cells (iSTCs) demonstrated abnormal staining patterns for SMARCA4/BRG1 [CHC: 4/4 (100%); iSTCs: 12/12 (100%), respectively], including focal or diffuse loss of expression in a subset of cases. The results of our study suggest that functional loss of SMARCA4/BRG1 represents a recurrent event that may be relevant for the pathogenesis of a subset of testicular CHC.

SMARCB1 (INI-1)-Deficient Sinonasal Carcinoma: A Systematic Review and Pooled Analysis of Treatment Outcomes

(1) Background: SMARCB1 (INI-1)-deficient sinonasal carcinoma is a rare sinonasal malignancy; since its discovery and description in 2014, less than 200 cases have been identified. It is almost impossible to perform randomized-controlled trials on novel therapy to improve treatment outcomes in view of its rarity. We performed a systematic review of all the published case reports/series and included our patients for survival analysis. (2) Methods: In this systematic review, we searched from PubMed-MEDLINE, EMBASE, Scopus, Cochrane Library, CINAHL, and Google Scholar for individual patient data to identify and retrieve all reported SMARCB1-deficient sinonasal carcinoma. Clarification on treatment details and the most updated survival outcomes from all authors of the published case reports/series were attempted. Survival analysis for overall survival (OS) and identification of OS prognostic factors were performed. This systematic review was registered with PROSPERO (CRD42022306671). (3) Results: A total of 67 publications were identified from the systematic review and literature search. After excluding other ineligible and duplicated publications, 192 patients reported were considered appropriate for further review. After excluding duplicates and patients with incomplete pretreatment details and survival outcomes, 120 patients were identified to have a complete set of data including baseline demographics, treatment details, and survival outcomes. Together with 8 patients treated in our institution, 128 patients were included into survival analysis. After a median follow up of 17.5 months (range 0.3-149.0), 50 (46.3%) patients died. The 1-year, 2-year and 3-year OS rates were 84.3% (95% CI % 77.6-91.0), 62.9% (95% CI 53.1-72.7), and 51.8% (95% CI 40.8-62.8), respectively, and the median OS was 39.0 months (95% CI 28.5-49.5). Males (p = 0.029) and T4b disease (p = 0.013) were significant OS prognostic factors in univariable analysis, while only T4b disease (p = 0.017) remained significant in multivariable analysis. (4) Conclusions: SMARCB1-deficient sinonasal carcinoma is an extremely aggressive sinonasal malignancy with a dismal prognosis. Early diagnosis and a multimodality treatment strategy are essential for a better treatment and survival outcome.

INI-1-Deficient Sinonasal Carcinoma: Case Report with Emphasis on Differential Diagnosis

SMARCB1-deficient sinonasal carcinoma is a newly described entity, with less than 100 reported cases. It is characterized by basaloid or rhabdoid morphology and is diagnosed by complete loss of nuclear SMARCB1 (INI-1). The morphologic appearance, specific immunophenotypic markers, and unique molecular make-up distinguish this entity from other various malignant neoplasms. We present a case of a 55-year-old male that presented with a large progressing palatine mass. Magnetic resonance imaging showed a heterogeneous mass involving the left maxillary space. The initial biopsy was diagnosed as undifferentiated carcinoma. Resection was performed, and immunohistochemical studies revealed a complete loss of INI-1, refining the diagnosis to SMARCB1-deficient sinonasal carcinoma. Diagnosis of SMARCB1-deficient sinonasal carcinoma should be considered in all undifferentiated sinonasal carcinomas. Immunohistochemistry or molecular studies are mandatory to confirm the diagnosis and exclude other morphologically similar entities.

Proceedings of the North American Society of Head and Neck Pathology, Los Angeles, CA, March 20, 2022: SWI/SNF-deficient Sinonasal Neoplasms: An Overview

The pathology of poorly differentiated sinonasal malignancies has been the subject of extensive studies during the last decade, which resulted into significant developments in the definitions and histo-/pathogenetic classification of several entities included in the historical spectrum of "sinonasal undifferentiated carcinomas (SNUC)" and poorly differentiated unclassified carcinomas. In particular, genetic defects leading to inactivation of different protein subunits in the SWI/SNF chromatin remodeling complex have continuously emerged as the major (frequently the only) genetic player driving different types of sinonasal carcinomas. The latter display distinctive demographic, phenotypic and genotypic characteristics. To date, four different SWI/SNF-driven sinonasal tumor types have been recognized: SMARCB1(INI1)-deficient carcinoma (showing frequently non-descript basaloid, and less frequently eosinophilic, oncocytoid or rhabdoid undifferentiated morphology), SMARCB1-deficient adenocarcinomas (showing variable gland formation or yolk sac-like morphology), SMARCA4-deficient carcinoma (lacking any differentiation markers and variably overlapping with large cell neuroendocrine carcinoma and SNUC), and lastly, SMARCA4-deficient sinonasal teratocarcinosarcoma. These different tumor types display highly variable immunophenotypes with SMARCB1-deficient carcinomas showing variable squamous immunophenotype, while their SMARCA4-related counterparts lack such features altogether. While sharing same genetic defect, convincing evidence is still lacking that SMARCA4-deficient carcinoma and SMARCA4-deficient teratocracinosarcoma might belong to the spectrum of same entity. Available molecular studies revealed no additional drivers in these entities, confirming the central role of SWI/SNF deficiency as the sole driver genetic event in these aggressive malignancies. Notably, all studied cases lacked oncogenic IDH2 mutations characteristic of genuine SNUC. Identification and precise classification of these entities and separating them from SNUC, NUT carcinoma and other poorly differentiated neoplasms of epithelial melanocytic, hematolymphoid or mesenchymal origin is mandatory for appropriate prognostication and tailored therapies. Moreover, drugs targeting the SWI/SNF vulnerabilities are emerging in clinical trials.

Clinical diagnosis and treatment analyses on SMARCB1 (INI-1)-deficient sinonasal carcinoma: case series with systematic review of the literature

OBJECTIVE

This study aims to improve the understanding of SMARCB1 (INI-1)-deficient sinonasal carcinoma (SDSC) by analyzing its clinical features, treatment strategies and prognosis.

METHODS

Sixty-nine patients were included in this research: 15 new cases from Beijing Tongren Hospital, and 54 previously reported cases. We analyzed and summarized patients' epidemiological data, clinical features, and treatment regimens. Main outcomes were overall survival (OS) and recurrence-free survival (RFS). Univariate and multivariate analyses were performed using a Cox regression model for OS and RFS.

RESULTS

SDSC was more common in men than womanwith a median age of 52 (ranged from 21 to 89 years). Epistaxis (40.0%) and headache (36.7%) were the major complaints. The most common affected paranasal sinus was the ethmoid sinus (58.0%). For TNM stage, 66.7% cases were first diagnosed as T4N0M0. The tumor cells were complete loss of INI-1 in all cases by immunohistochemical analysis. However, 72.5% cases were first misdiagnosed initially. The 1-year, 3-year, and 5-year OS and RFS were 85.3%, 51.8%, 47.8%; and 56.8%, 38.2%, 35.3% respectively. The RFS of comprehensive treatment based on surgery was better than that of systemic therapy without surgery (P<0.05), Additionally, the OS and RFS of surgery with chemoradiotherapy was better than that of surgery with radiotherapy (P<0.05). Univariate and multivariate analysis identified treatment modality as an independent prognostic factor for SDSC patients.

CONCLUSION

Immunohistochemical analysis of SDSC during initial biopsy can prevent delays in diagnosis and treatment. Radical surgery resection combined with chemoradiotherapy may be the preferred treatment modality.

Methylation Drivers and Prognostic Implications in Sinonasal Poorly Differentiated Carcinomas

Simple Summary

Poorly differentiated sinonasal carcinomas (PDSNCs) are rare neoplasms that include a wide spectrum of malignancies characterized by alteration in different epigenetic mechanisms (SWI/SNF complex, IDH2, NUT). The aim of our study was to verify if the identification of specific genetic and epigenetic alterations can be useful to recognize different clinico-pathological subsets of PDSNCs to guide treatment decisions. In our cohort, 14 cases showed alterations in SWI/SNF complex or IDH2 genes, which were associated with a higher global DNA methylation level and worst prognosis. The integration of genetic and epigenetic features appears to be a good strategy to improve the clinico-pathological classification of these tumors and to recognize distinct prognostic entities that deserve tailored clinical management.

Abstract

Background: Poorly differentiated sinonasal carcinomas (PDSNCs) are rare and aggressive malignancies, which include squamous cell carcinoma (SCC), sinonasal undifferentiated carcinoma (SNUC), and neuroendocrine carcinomas (NEC). Several epigenetic markers have been suggested to support the histopathological classification, predict prognosis, and guide therapeutic decision. Indeed, molecularly distinct subtypes of sinonasal carcinomas, including SMARCB1-INI1 or SMARCA4 deficient sinonasal carcinoma, isocitrate dehydrogenase (IDH)-mutant SNUC, ARID1A mutant PDSNCs, and NUT carcinomas, have recently been proposed as separate entities. Identification of aberrant DNA methylation levels associated with these specific epigenetic driver genes could be useful for prognostic and therapeutic purpose. Methods: Histopathological review and immunohistochemical study was performed on 53 PDSNCs. Molecular analysis included mutational profile by NGS, Sanger sequencing, and MLPA analyses, and global DNA methylation profile using LINE-1 bisulfite-PCR and pyrosequencing analysis. Results: Nine SWI/SNF complex defective cases and five IDH2 p.Arg172x cases were identified. A significant correlation between INI-1 or IDH2 defects and LINE-1 hypermethylation was observed (p = 0.002 and p = 0.032, respectively), which were associated with a worse prognosis (p = 0.007). Conclusions: Genetic and epigenetic characterization of PDSNCs should be performed to identify distinct prognostic entities, which deserved a tailored clinical treatment.

SMARCB1(INI1)-deficient sinonasal adenocarcinoma: Report of a case previously diagnosed as high-grade non-intestinal-type sinonasal adenocarcinoma

SMARCB1(INI1)-deficient sinonasal carcinoma is a recently recognized entity with wide histomorphologic spectrum. The classification of sinonasal adenocarcinoma (SNAC) is complex and yet to be redefined, especially the category of high-grade non-intestinal-type SNAC. Recently SMARCB1(INI1)-deficient SNACs with an unique oncocytoid/rhabdoid cytomorphology and variable degrees of glandular formation have been reported. Here we described a rare case of SMARCB1(INI1)-deficient SNAC composed of mainly oncocytoid/rhabdoid cells with mixed solid and cribriform patterns. This case was originally diagnosed as non-intestinal-type SNAC and was reclassified due to complete loss expression of SMARCB1(INI1) by immunohistochemistry (IHC). The SMARCB1(INI1) stain provides a valuable tool for identification of this specific type of SNAC. We compared this case with other SNACs diagnosed in our department and reviewed relevant literature for this specific type of SNAC.

SWI/SNF-deficient head and neck neoplasms: An overview

With wide-spread use of next generation sequencing tools in surgical pathology, a variety of neoplasms have been increasingly recognized to be associated with specific recurrent defining genetic abnormalities. This has led to recognition of new genetically defined entities and refinements of preexisting heterogeneous neoplastic categories. Among these, neoplasms associated with inactivating mutations involving different subunits of the SWI/SNF chromatin remodeling complex have received special attention. In the head and neck area, SMARCB1 (INI1) and SMARCA4 (BRG1) are the main two SWI/SNF components responsible for several recently described highly aggressive undifferentiated malignancies with predilection for the soft tissue of the neck (SMARCB1-deficient malignant rhabdoid tumors in children and rare epithelioid sarcoma cases in adults) and the sinonasal tract (SMARCB1-deficient sinonasal carcinoma including a small subset of adenocarcinomas, SMARCA4-deficient sinonasal undifferentiated carcinoma and SMARCA4-deficient sinonasal teratocarcinosarcoma). Molecular studies confirmed paucity of additional genetic abnormalities in these diseases underlining the central role of SWI/SNF deficiency as the primary and frequently sole genetic driver of these lethal diseases. Initiation of clinical trials using drugs that target the SWI/SNF collapse encourages recognition and correct classification of these morphologically frequently overlapping malignancies and underpins the role of SWI/SNF immunohistochemistry as emerging powerful adjunct tool in surgical pathology of the head and neck.

Recurrent Loss of SMARCA4 in Sinonasal Teratocarcinosarcoma

Molecular analysis has reshaped the landscape of high grade sinonasal tumors by defining novel entities and identifying recurrent mutations in established tumor types. However, sinonasal teratocarcinosarcoma (TCS), a rare and aggressive tumor with intermixed teratomatous, carcinomatous, and sarcomatous elements, remains poorly understood. The multiphenotypic differentiation of TCS has engendered persistent controversy about its histogenesis and leads to diagnostic overlap with several other malignancies. In this study, we evaluated the molecular underpinnings of TCS to clarify its pathogenesis and diagnosis. We performed SMARCA4 immunohistochemistry (IHC) on 22 TCS and 153 other sinonasal tumors. We identified loss of SMARCA4 expression in 18 TCS (82%), including 15 (68%) with complete loss and 3 (14%) with partial loss. Although we also identified partial SMARCA4 loss in 1 of 8 SMARCB1-deficient sinonasal carcinomas (13%), SMARCA4 was intact in all other sinonasal carcinomas and neuroendocrine tumors. We then selected 3 TCS with complete SMARCA4 loss by IHC for a targeted next-generation sequencing panel that included 1425 cancer-related genes. We confirmed biallelic somatic inactivation of SMARCA4 without other known oncogenic mutations in these 3 cases. Overall, these findings suggest that SMARCA4 inactivation may be the dominant genetic event in TCS, expanding understanding of this gene's role in sinonasal tumorigenesis. They also raise the possibility that TCS is on a diagnostic spectrum with the newly described SMARCA4-deficient sinonasal carcinoma, blurring the lines between established and emerging sinonasal entities. In addition, SMARCA4 IHC may provide a useful adjunct for confirming a diagnosis of TCS in limited material.

SMARCB1/INI1 Deficient Sino-Nasal Carcinoma: Extending the Histomorphological Features

SMARCB1/INI1 deficient sinonasal carcinoma is a variant of sinonasal undifferentiated carcinoma (SNUC). There is a paucity of literature describing the histomorphological features of this relatively new entity. Herein we describe the histomorphological features of three such cases and review the literature. We retrospectively reviewed the cases of SNUC diagnosed in our institute in the last 6 years. Immunohistochemistry for INI1, NUT & p16 were performed on these cases. Three cases showed loss of INI1. The histomorphology and clinicopathological features of these cases were studied and compared with non INI1 deficient SNUC. A total of 9 cases of SNUC were identified. Three of these cases showed loss of INI1. These three cases had presented with large sinonasal mass and with intracranial extension. Histopathology of these cases showed a diffuse infiltrative pattern, nest, and islands of predominantly basaloid cells with focal rhabdoid morphology. Additional features like small cell carcinoma like pattern, pseudoalveolar and pseudoglandular patterns, clear vacuoles and pseudopapillary appearance were also noted. We conclude that in presence of a mixed pattern of cells with a predominance of basaloid morphology, the possibility of SMARCB1/INI1 deficient sinonasal carcinoma must be strongly suspected and immunohistochemistry for INI1 must be performed.

The Role of Adjuvant Treatment in Craniofacial Malignancy: A Critical Review

Background: Tumors originating from the craniofacial region usually present in a locally advanced stage with frequent involvement of adjacent sites and have a strong tendency for local recurrence in the absence of adjuvant therapy, even when the original surgical resection was presumed to be radical. In the past decades, several advances in the radiological diagnosis and treatment of craniofacial malignancies have been introduced. There are, however, no randomized trials that define the optimal multimodal treatment of these tumors because of their rarity as well as heterogeneity in both histology and site of origin. The aim of this study was to conduct a critical review of the role of adjuvant therapy in the treatment of craniofacial malignancy. Method: We conducted a critical review of the past and contemporary literature available, focusing on adjuvant oncological treatments of the most common craniofacial malignancies. Results: Preoperative radiotherapy can have a documented role in the treatment of olfactory neuroblastoma and soft tissue sarcoma, while preoperative chemotherapy can be advocated in the treatment of sinonasal undifferentiated carcinoma, neuroendocrine carcinoma, olfactory neuroblastoma, and craniofacial sarcoma (both soft-tissue and high-grade osteosarcoma). Postoperative radiotherapy has a well-established role in the treatment of most craniofacial malignancies. The role of postoperative chemotherapy is unclear in most histologies, but is commonly used during the treatment of well-selected cases of paranasal sinus carcinoma, olfactory neuroblastoma, mucosal melanoma, soft tissue sarcoma and high-grade craniofacial osteosarcoma. Discussion: Alongside developments in surgery, there have also been improvements in diagnostics, radiotherapy, and chemotherapy. Implementation of novel radiation techniques allows delivery of higher radiation doses while minimizing irradiation-related morbidity. Better understanding of tumor biology allows the construction of more complex treatment strategies, incorporating adjuvant chemotherapy either pre- or postoperatively. In the era of personalized targeted therapy, rapid strides are being made to identify specific tumor-targets for use of novel biologic agents, with the potential to change current management paradigms.

Fulminant presentation of a SMARCB1-deficient, anterior cranial fossa tumor in adult

Background:

Malignant atypical teratoid rhabdoid tumor (ATRT) usually develops in children. ATRTs are rare in adults, with only one case in the literature describing involvement of the anterior skull base. These primary intracranial tumors are characterized molecularly as SMARCB1 (INI1) deficient. Different types of such SMARCB1-deficient tumors exist in adulthood, usually in the form of extracranial tumors. Very few cases of such a new entity, named SMARCB1-deficient sinonasal carcinoma have been described with intracranial penetration and involvement of the anterior cranial fossa.

Case Description:

A 36-year-old male presented with acute cognitive deterioration. Over few hours, he developed a fulminant herniation syndrome. Imaging showed a tumor in the anterior cranial fossa surrounded by massive brain edema. The tumor has destroyed the frontal bone with involvement of the nasal cavities and paranasal sinuses. The patient underwent emergent decompressive craniectomy and tumor debulking but could not be saved. Pathological analysis revealed a highly cellular tumor without rhabdoid cells but with areas of necrosis. Further immunohistochemical stains revealed that neoplastic cells were diffusely and strongly positive for epithelial membrane antigen and P63 and negative for SMARCB1 (i.e., loss of expression), confirming the diagnosis of sinonasal carcinoma.

Conclusion:

To the best of our knowledge, this is the first report of a fulminant presentation of a SMARCB1- deficient tumor in young adult, involving the anterior cranial fossa and the paranasal sinuses. The main differential diagnosis of aggressive, primary, intracranial SMARCB1-deficient tumors in adults includes ATRT, SMARCB1- deficient sinonasal carcinoma, rhabdoid meningioma, and rhabdoid glioblastoma. Atypical tumors involving the anterior skull base without a clear histopathological pattern should therefore be checked for SMARCB1 expression.

Sinonasal Undifferentiated Carcinoma (SNUC): From an Entity to Morphologic Pattern and Back Again-A Historical Perspective

Since the first description of sinonasal undifferentiated carcinoma (SNUC) as a distinctive highly aggressive sinonasal neoplasm with probable origin from the sinonasal mucosa (Schneiderian epithelium), SNUC has been the subject of ongoing study and controversy. In particular, the SNUC category gradually became a "wastebasket" for any undifferentiated or unclassifiable sinonasal malignancy of definite or probable epithelial origin. However, with the availability of more specific and sensitive immunohistochemical antibodies and increasing implementation of novel genetic tools, the historical SNUC category became the subject of progressive subdivision leading to recognition of specific genetically defined, reproducible subtypes. These recently recognized entities are characterized by distinctive genetic aberrations including NUTM1-rearranged carcinoma (NUT carcinoma) and carcinomas associated with inactivation of different members of the SWI/SNF chromatin-remodeling gene complex such as SMARCB1-deficient and less frequently SMARCA4-deficient carcinoma. The ring became almost closed, with recent studies highlighting frequent oncogenic IDH2 mutations in the vast majority of histologically defined SNUCs, with a frequency of 82%. A review of these cases suggests the possibility that "true SNUC" probably represents a distinctive neoplastic disease entity, morphologically, phenotypically, and genetically. This review addresses this topic from a historical perspective, with a focus on recently recognized genetically defined subsets within the SNUC spectrum.

SMARCB1-Deficient Sinonasal Carcinoma: Systematic Review and Case Report

INTRODUCTION

To describe the current state of literature involving SMARCB1/INI-1 deficient sinonasal carcinoma (SDSC) and examine a case at our institution.

METHODS

A systematic search was performed using the Population, Intervention, Comparator, Outcome, and Study Design approach. Search criteria included all occurrences in the title or abstract of the terms: "integrase interactor 1 deficient," "INI1 deficient," or "SMARCB1 deficient" and "sinonasal carcinoma." The main outcomes were disease-free survival, all-cause mortality, rates of recurrence, or metastases.

RESULTS

Systematic search yielded 13 studies for final review. All studies were either case series or case reports with 82 cases of SDSC published since 2014. Age on presentation ranged from 19 to 75 years, with the majority of patients being male. Surgical resection was the primary modality of treatment with adjuvant radiation or chemoradiation therapy. Overall, the prognosis was poor, with most tumors presenting at advanced stages with an overall median (range) survival of 22 (12-44) months with an average (standard deviation) of 45.3% (33.1%) of patients dying of the disease. An average (standard deviation) of 38.2% (34.0%) of patients had no evidence of disease at follow-up. Studies comparing sinonasal undifferentiated carcinoma to SDSC reported worse prognosis for SDSC and increased risk for locoregional recurrence in the latter cohort.

CONCLUSIONS

SDSC represents a highly aggressive tumor presenting at advanced stage with propensity of metastasis. More research is necessary to determine the optimal treatment modality and management.

SMARCB1 (INI-1)-Deficient Adenocarcinoma of the Sinonasal Tract: A Potentially Under-Recognized form of Sinonasal Adenocarcinoma with Occasional Yolk Sac Tumor-Like Features

The classification of sinonasal adenocarcinoma (SNAC) is complex. The high-grade, non-intestinal SNAC group is particularly heterogeneous, with tumors showing widely variable morphology. SMARCB1 (INI-1)-deficient sinonasal carcinoma is a newly described, aggressive tumor that usually resembles sinonasal undifferentiated carcinoma (SNUC) or non-keratinizing squamous cell carcinoma; however, glandular differentiation has been rarely reported and this feature may be under-recognized. We present a dedicated series of 12 SMARCB1-deficient SNACs. All tumors had an oncocytoid/plasmacytoid cytomorphology with variable degrees of glandular differentiation consisting of tubules and cribriform structures with foci of intracellular or intraluminal mucin. Three of 12 tumors exhibited foci of yolk sac tumor-like histologic features. The tumors were uniformly high-grade, with nuclear pleomorphism, elevated mitotic rates and frequent necrosis. By immunohistochemistry, all tumors were entirely SMARCB1-deficient, and 10 of 12 were CK7-positive. Occasional expression of CDX2 (4 of 12), CK20 (3 of 12), and p40 (3 of 10) was seen. Expression of yolk sac markers was variably present in tumors that harbored yolk sac-like areas but also tumors that did not: glypican-3 (10 of 11), SALL4 (6 of 11), HepPar-1 (4 of 11), PLAP (1 of 10), and AFP (1 of 11). SMARCB1-deficient sinonasal carcinoma, particularly the oncocytoid/plasmacytoid form, can demonstrate variable degrees of glandular differentiation. This unexpected morphology combined with variable immunohistochemical results may lead to misdiagnoses of high-grade intestinal or non-intestinal SNAC, myoepithelial carcinoma, or even yolk sac tumor or metastatic hepatocellular carcinoma.

Loss of SMARCB1 Expression Confers Poor Prognosis to Sinonasal Undifferentiated Carcinoma

Background  Due to the diverse histopathologic features and variable survival rates seen in sinonasal undifferentiated carcinoma (SNUC), it is likely that this diagnostic entity is comprised of a heterogonous group of morphologically undifferentiated tumors. As advancements in molecular testing have led to a better understanding of tumor biology, it has become increasingly evident that SNUC may actually encompass several tumor subtypes with different clinical behavior. As a result, it is also likely that all SNUC patients cannot be treated in the same fashion. Recent investigations have identified loss of the tumor suppressor SMARCB1 (INI1) expression in a subset of undifferentiated sinonasal tumors and extrasinonasal tumors and, studies have suggested that this genetic aberration may be a poor prognostic marker. The objective of this study was to identify differential expression of SMARCB1 in SNUC and to analyze and compare the survival outcomes in SNUC patients with and without SMARCB1 expression. Methods  All cases of undifferentiated or poorly differentiated neoplasms of the sinonasal tract treated between 2007 and 2018 at a single tertiary care institution were selected. All cases of SNUC were tested for SMARCB1 status by immunohistochemistry (IHC). Clinical parameters were analyzed using Student's t -test and Fischer's test. Kaplan-Meier methods were used to estimate survival durations, while comparison between both the subgroups was done using the log-rank test. Statistical analysis was performed with the use of SPSS software, Version 25 (IBM, New York, NY, United States). Results  Fourteen cases of SNUC were identified. Approximately two-thirds (64%; n  = 9) of patients were male and the majority (79%; n  = 11) were between fifth to seventh decade. Skull base and orbital invasion were seen in 79% ( n  = 11) and 93% ( n  = 13) of cases, respectively. Fifty-seven percent of tumors ( n  = 8) retained SMARCB1 expression by IHC (SR-SNUC), while the remaining 43% ( n  = 6) showed loss of SMARCB1 expression and, thus, were considered as SMARCB1 -deficient (SD-SNUC). Although clinicopathological features and treatment modalities were similar, SD-SNUC showed poorer (OS: p  = 0.07; disease free survival [DFS]: p  = 0.02) overall survival (OS) and DFS on Kaplan-Meier curves. Additionally, SD-SNUC showed higher recurrence (75 vs. 17%) and mortality (67 vs. 14%) (hazard rate = 8.562; p  = 0.05) rates. Both OS (28.82 ± 31.15 vs. 53.24 ± 37.50) and DFS durations (10.62 ± 10.26 vs. 43.79 ± 40.97) were consistently worse for SD-SNUC. Five-year survival probabilities were lower for SD-SNUC (0.33 vs. 0.85). Conclusion  SNUC represents a heterogeneous group of undifferentiated sinonasal malignancies. Based on the status of SMARCB1 expression, the two subgroups SD-SNUC and SR-SNUC appear to represent distinct clinical entities, with loss of SMARCB1 expression conferring an overall worse prognosis.

Metastatic SMARCB1 (INI-1)-Deficient Sinonasal Carcinoma Diagnosed by Endobronchial Ultrasound-Guided Fine-Needle Aspiration (EBUS-FNA): A Potential Diagnostic Pitfall and Review of the Literature

SMARCB1 (INI-1)-deficient sinonasal carcinoma is a rare entity within the subgroup of poorly differentiated sinonasal tract carcinomas. As there are only two papers describing the cytologic features of this entity, herein we describe the unique cytomorphologic features of a pulmonary metastasis of this tumor and include the differential diagnosis based on tumor location. The patient was a 53-year-old male who initially presented with sinus congestion and vision changes including left-eye proptosis and diplopia. The initial biopsy of the ethmoid-centered sinonasal mass was non-keratinizing squamous cell carcinoma based on strong immunoreactivity with p40 and absence of immunoreactivity for chromogranin, synaptophysin, p16, and EBER. However, the final diagnosis of the surgical resection was amended to SMARCB1 (INI-1)-deficient sinonasal carcinoma after additional immunohistochemical stains were performed. Post-primary resection, follow-up computed tomography imaging revealed significant interval progression of a solitary, initially indeterminate 1-cm lung nodule in the left upper lobe. Endobronchial ultrasound-guided fine-needle aspiration with concomitant core-needle biopsy was performed. Rapid on site evaluation of cytologic smears revealed a hypercellular specimen consisting of sheets of epithelioid cells with very scant to absent cytoplasm, ill-defined cell borders, enlarged fragile nuclei, and areas of nuclear molding. Mitotic figures were present. Other areas showed tumor cells with spindled to elongated nuclei and scant to ill-defined wispy cytoplasm. Both cytology cell block and core-needle biopsy histopathologic material showed the tumor cells to be negative for INI-1 nuclear staining as well as CK5/6, CAM5.2, p40, p63, CK7, AE1/3, and TTF-1. SMARCB1 (INI-1)-deficient sinonasal carcinoma can have a spectrum of morphologies and may mimic "small-round-blue-cell" and spindle-cell tumors on cytology preparations. Given the pulmonary location of the aspirate, familiarity with the cytomorphologic spectrum of SMARCB1 (INI-1)-deficient sinonasal carcinoma, inclusion of this entity within the differential diagnosis, and performance of immunohistochemistry will aid in arriving at the correct diagnosis.

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.

Sinonasal Undifferentiated Carcinoma

PURPOSE OF REVIEW

To provide a comprehensive review of the literature highlighting the recent advances in the diagnosis and management of sinonasal undifferentiated carcinoma (SNUC) RECENT FINDINGS: SNUC usually presents at advanced stage and the prognosis is usually poor with high rates of locoregional recurrence and tendency to metastasize. Special attention should be made in differentiating SNUC from other sinonasal malignancies in order to guide the appropriate treatment accordingly. Multimodality treatment is usually recommended for treating SNUC. The use of neoadjuvant chemotherapy may be associated with improved outcome and can be used to guide the subsequent treatment selection. Despite the recent advances in chemotherapeutic agents, radiation techniques, and surgical approaches, the prognosis and survival outcomes of SNUC remain poor. The addition of induction chemotherapy to the treatment approach followed by definitive local therapy needs to be further studied as it might improve the outcome.

SMARCB1 (INI1)-deficient sinonasal carcinoma: a series of 13 cases with assessment of histologic patterns

A significant proportion of sinonasal malignancies comprise poorly differentiated/undifferentiated carcinomas that defy accurate histologic classification and behave aggressively. Recent years have seen a refinement of this spectrum by inclusion of novel entities harboring specific genetic alterations, including SMARCB1 (INI1)-deficient sinonasal carcinoma (SDSC), characterized by inactivating alterations in SMARCB1 gene, as demonstrated by loss of INI1 immunoexpression. Cyclin D1 is a cell-cycle regulatory protein downstream of INI1. Loss of INI1 leads to derepression of cyclin D1 transcription, suggesting its role as a putative therapeutic target. However, cyclin D1 expression has not been assessed in SDSCs. We retrieved all sinonasal carcinomas, including sinonasal undifferentiated carcinoma, undifferentiated carcinoma, poorly differentiated squamous cell carcinoma, and adenocarcinoma. Histopathologic features were reviewed. INI1 immunohistochemistry was performed. Cyclin D1 was performed in cases showing INI1 loss. Loss of INI1 staining was seen in 13 cases (5.8%), including 11 males and 2 females (age range, 11-65 years). Original diagnoses included SDSC (3/13), sinonasal undifferentiated carcinoma (3/13), adenocarcinoma (3/13), poorly differentiated squamous cell carcinoma (2/13), and poorly differentiated carcinoma (2/13). Tumors were predominantly basaloid in 6 cases and plasmacytoid/rhabdoid in 5 cases. We identified 2 cases having oncocytoid cells arranged in a gland-like pattern. Significant cyclin D1 immunoexpression was absent. SDSC is a rare, emerging entity that resembles a poorly differentiated carcinoma. Histomorphologic spectrum of these tumors is evolving. In addition to basaloid and plasmacytoid/rhabdoid cells, oncocytoid/adenocarcinoma-like pattern can also be seen in SDSC and predicts INI1 loss. These histologic patterns can further be subjected to INI1 immunohistochemistry for correct diagnosis.

Sinonasal SMARCB1 (INI1) Deficient Carcinoma With Yolk Sac Tumor Differentiation: Report of a Case and Comparison With INI1 Expression in Gonadal Germ Cell Tumors

SMARCB1 (INI1) deficient sinonasal carcinoma is a recently recognized entity with wide histomorphologic spectrum. We present a case of this carcinoma that contained, in addition to a "common" morphology, scattered foci of yolk sac tumor differentiation. The tumor occurred in paranasal sinuses in a 44-year-old woman. Immunohistochemically, it was diffusely negative for INI1, whereas an expression of yolk sac tumor markers (α-fetoprotein, glypican-3, CDX2) was limited to the yolk sac tumor component. For comparison with the present case, we performed INI1 immunostaining on a series of 11 gonadal germ cell tumors with yolk sac tumor differentiation. All of these cases showed strong and diffuse expression of INI1, in contrast with the present sinonasal tumor. Our findings expand the morphologic spectrum of SMARCB1 (INI1) deficient sinonasal carcinoma. In addition, we show preliminarily that gonadal germ cell tumors with yolk sac tumor differentiation are not SMARCB1/INI1-deficient.

Updates on Immunohistochemical and Molecular Markers in Selected Head and Neck Diagnostic Problems

CONTEXT

- The head and neck regions have complex anatomic structures. They are not exempted from the rare occurrences of highly unusual, diagnostically challenging malignant neoplasms and mimickers.

OBJECTIVE

- To review and update the utility of immunohistochemistry and molecular biomarkers and to pursue diagnostic accuracy on selected rare neoplasms, especially some poorly differentiated malignancies.

DATA SOURCES

- Personal experience and information from the literature.

CONCLUSIONS

- Head and neck tumors include neoplasms originating from heterogeneous tissue. Using the selected clinical cases, this review illustrates a continuous development of emerging molecular-genetic techniques to assist in the interpretation of uncommon, often poorly differentiated, highly malignant neoplasms. The diagnostic results are appropriately transmitted to the oncologists, radiation oncologists, and surgeons to create a coordinated plan of care for patients with these unusual disorders affecting the head and neck.

SMARCB1 (INI-1)-deficient Sinonasal Carcinoma: A Series of 39 Cases Expanding the Morphologic and Clinicopathologic Spectrum of a Recently Described Entity

To more fully characterize the clinical and pathologic spectrum of a recently described tumor entity of the sinonasal tract characterized by loss of nuclear expression of SMARCB1 (INI1), we analyzed 39 SMARCB1-deficient sinonasal carcinomas collected from multiple medical centers. The tumors affected 23 males and 16 females with an age range of 19 to 89 years (median, 52). All patients presented with locally advanced disease (T3, n=5; T4, n=27) involving the sinuses (mainly ethmoid) with variable involvement of the nasal cavity. Thirty patients received surgery and/or radiochemotherapy with curative intent. At last follow-up, 56% of patients died of disease 0 to 102 months after diagnosis (median, 15), 2 were alive with disease, and 1 died of an unrelated cause. Only 9 patients (30%) were alive without disease at last follow-up (range, 11 to 115 mo; median, 26). The original diagnosis of retrospectively identified cases was most often sinonasal undifferentiated carcinoma (n=14) and nonkeratinizing/basaloid squamous cell carcinoma (n=5). Histologically, most tumors displayed either a predominantly basaloid (61%) or plasmacytoid/rhabdoid morphology (36%). The plasmacytoid/rhabdoid form consisted of sheets of tumor cells with abundant, eccentrically placed eosinophilic cytoplasm, whereas similar cells were typically rare and singly distributed in the basaloid variant. Glandular differentiation was seen in a few tumors. None of the cases showed squamous differentiation or surface dysplasia. By immunohistochemistry, the tumors were positive for pancytokeratin (97%), CK5 (64%), p63 (55%), and CK7 (48%); and they were negative for NUT (0%). Epstein-Barr virus and high-risk human papillomavirus was not detected by in situ hybridization. Immunohistochemical loss of SMARCB1 (INI1) expression was confirmed for all 39 tumors. Investigation of other proteins in the SWI/SNF complex revealed co-loss of SMARCA2 in 4 cases, but none were SMARCA4 deficient or ARID1A deficient. Of 27 tumors with SMARCB1 fluorescence in situ hybridization analysis, 14 showed homozygous (biallelic) deletions and 7 showed heterozygous (monoallelic) deletions. SMARCB1-deficient sinonasal carcinoma represents an emerging poorly differentiated/undifferentiated sinonasal carcinoma that (1) cannot be better classified as another specific tumor type, (2) has consistent histopathologic findings (albeit with some variability) with varying proportions of plasmacytoid/rhabdoid cells, and (3) demonstrates an aggressive clinical course. This entity should be considered in any difficult-to-classify sinonasal carcinoma, as correct diagnosis will be mandatory for optimizing therapy and for further delineation of this likely underdiagnosed disease.

Claudin-4 expression distinguishes SWI/SNF complex-deficient undifferentiated carcinomas from sarcomas

Inactivation of SWI/SNF (switch/sucrose non-fermentable) chromatin remodeling complex subunits is a feature shared by select carcinomas and sarcomas with epithelioid morphology and variable keratin expression, making the distinction between carcinoma and sarcoma challenging in some cases. The tight junction-associated protein claudin-4 is a marker of epithelial differentiation that is expressed in nearly all carcinomas. Claudin-4 expression has been reported in the glandular component of biphasic synovial sarcoma but has not been systematically evaluated in other sarcoma types. In this study we assessed claudin-4 expression in SWI/SNF complex-deficient neoplasms showing loss of SMARCB1 (INI1), SMARCA4 (BRG1), or ARID1A and other sarcomas with epithelioid morphology. Immunohistochemistry for claudin-4 was performed on 130 neoplasms, including 90 soft tissue tumors with epithelioid morphology and/or SMARCB1 deficiency (20 epithelioid sarcomas (10 conventional, 10 proximal-type); 10 epithelioid angiosarcomas; 10 epithelioid hemangioendotheliomas; 15 epithelioid malignant peripheral nerve sheath tumors; 10 malignant rhabdoid tumors; 15 myoepithelial carcinomas; 10 biphasic synovial sarcomas), 10 ovarian clear cell carcinomas, 10 ovarian small cell carcinomas of hypercalcemic type, and 20 SWI/SNF complex-deficient undifferentiated carcinomas (14 SMARCB1 deficient and 6 SMARCA4 deficient, including rhabdoid carcinomas of various sites and sinonasal carcinomas). Membranous expression of claudin-4 (≥5% of cells) was observed in all biphasic synovial sarcomas (epithelial component only), all ovarian clear cell carcinomas, and 16 (80%) SWI/SNF complex-deficient undifferentiated carcinomas. All other soft tissue tumors were negative for claudin-4, with the exception of two myoepithelial carcinomas and one malignant rhabdoid tumor. Interestingly, none of the ovarian small cell carcinomas of hypercalcemic type expressed claudin-4. In summary, expression of claudin-4 is highly specific for true epithelial differentiation and may be useful to distinguish SWI/SNF complex-deficient undifferentiated carcinomas from sarcomas with epithelioid morphology. The lack of claudin-4 expression in ovarian small cell carcinomas of hypercalcemic type suggests that these tumors may be better regarded as sarcomas rather than carcinomas.

Clinical effects of p53 overexpression in squamous cell carcinoma of the sinonasal tract: A systematic meta-analysis with PRISMA guidelines

BACKGROUND

The level of p53 protein expression in sinonasal squamous cell carcinoma (SNSCC) has been estimated, but the results remain inconsistent and the point of consensus has not been reached. This study was first determined to evaluate the clinical effects of p53 expression in SCC of the sinonasal tract.

METHODS

According to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement criteria, the potential literature was searched from diverse databases. The pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated to assess the strength of association between p53 expression and SNSCC.

RESULTS

Final 17 eligible studies were included in a total of 258 cases and 748 controls. The result of p53 expression was shown to be notably higher in SNSCC than in benign sinonasal papillomas and normal sinonasal mucosa (OR = 26.93, P < 0.001; OR = 39.79, P < 0.001; respectively). Subgroup analyses of ethnicity revealed that p53 expression had significant association with SNSCC in Asian and Caucasian populations in cancer versus benign sinonasal papillomas or normal sinonasal mucosa. The expression of p53 was notably higher in moderately or poorly differentiated SNSCC than in well-differentiated SNSCC (OR = 3.51, P = 0.021), while p53 expression was not associated with histological type.

CONCLUSION

The results suggested that p53 overexpression may be correlated with the carcinogenesis and progression of SNSCC. The p53 gene may become a novel drug target of SNSCC. Additional studies on the correlation of p53 expression with clinicopathological features are needed.

Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: Tumors of the Nasal Cavity, Paranasal Sinuses and Skull Base

The sinonasal tract remains an epicenter of a diverse array of neoplasia. This paper discusses changes to the WHO classification system of tumors involving this area. In particular, seromucinous hamartoma, NUT carcinoma, biphenotypic sinonasal sarcoma, HPV-related carcinoma with adenoid cystic features, SMARCB1-deficient carcinoma, and renal cell-like adenocarcinoma are discussed.

SMARCB1/INI1-deficient sinonasal carcinoma shows methylation of RASSF1 gene: A clinicopathological, immunohistochemical and molecular genetic study of a recently described entity

The aim of the study was detailed clinicopathological investigation of SMARCB1/INI1-deficient sinonasal carcinomas, including molecular genetic analysis of mutational status and DNA methylation of selected protooncogenes and tumor suppressor genes by means of next generation sequencing (NGS) and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA). A total of 4/56 (7%) cases of SMARCB1/INI1-deficient carcinomas were detected among 56 sinonasal carcinomas diagnosed over a 19year period using immunohistochemical screening. The series comprised 3 males and 1 female, aged 27-76 years (median 64 years). All tumors arose in the nasal cavity. Three neoplasms were diagnosed in advanced stage pT4. During the follow-up period (range 14-111 months (median 72 months)), three tumors recurred locally, but none of the patients developed regional or distant metastases. Ultimately, two patients died due to the tumor. Microscopically, all tumors consisted of infiltrating nests of polygonal basaloid cells with a variable component of rhabdoid cells with eosinophilic cytoplasm. Immunohistochemically, there was almost diffuse expression of cytokeratins (CK), p16, p40 and p63 in all cases, while expression of CK5/6, CK7 and vimentin was only focal or absent. The detection of NUT gave negative results. In three cases, the absence of SMARCB1/INI1 expression was due to deletion of SMARCB1/INI1 gene. Methylation of SMARCB1/INI1 gene was not found. One tumor harbored HPV18 E6/E7 mRNA. All 12 genes (BRAF, BRCA1, BRCA2, KIT, EGFR, KRAS, NRAS, PDGFRA, PIK3CA, PTEN, RET, and ROS1) tested for mutations using NGS were wild-type. Regarding DNA methylation, all four SMARCB1/INI1-deficient tumors showed methylation of RASSF1 gene by means of MS-MLPA. There was a statistically significant difference in RASSF1 gene methylation between SMARCB1/INI1-deficient and SMARCB1/INI1-positive tumors (p=0.0095). All other examined genes (ATM, BRCA1, BRCA2, CADM1, CASP8, CD44, CDKN1B, CDKN2A, CDKN2B, CHFR, DAPK1, ESR1, FHIT, GSTP1, HIC1, KLLN, MLH1a, MLH1b, RARB, and VLH) were unmethylated. In summary, we described four cases of SMARCB1/INI1-deficient sinonasal carcinoma with detailed clinicopathological data indicating that these tumors can be regarded as a distinct entity with aggressive behaviour. For the first time, we performed analysis of DNA methylation in SMARCB1/INI1-deficient sinonasal carcinomas, reporting on significantly higher methylation of RASSF1 gene in this neoplasm.

Sinonasal Small Round Blue Cell Tumors: An Immunohistochemical Approach

Although clinical history and morphologic appearance should be the initial considerations when evaluating small round blue cell tumors of the sinonasal tract, the final diagnosis often hinges on immunohistochemical findings. Unfortunately, interpretation of stains in these tumors is fraught with numerous pitfalls and limitations. This article presents an approach to sinonasal small round blue cell tumors based on four common immunohistochemical patterns: cytokeratin positivity, squamous marker positivity, neuroendocrine marker positivity, and cytokeratin negativity.

Meta-analysis of 701 published cases of sinonasal neuroendocrine carcinoma: The importance of differentiation grade in determining treatment strategy

The aim of this meta-analysis was to provide treatment guidelines for sinonasal neuroendocrine carcinoma (SNC) by combining all available data in the literature. A literature search for all studies concerning SNC was performed against the MEDLINE and EMBASE databases. Available clinical data was normalized, pooled, and statistically analyzed. A total of 701 cases of SNC were available for analysis, comprising 127 well or moderately differentiated sinonasal neuroendocrine carcinomas (SNEC), 459 sinonasal undifferentiated carcinoma (SNUC) and 115 sinonasal small cell carcinoma (SmCC). Tumor type was the most important predictor of survival, with a 5-year disease-specific survival (DSS) of 70.2% for SNEC, 35.9% for SNUC and 46.1% for SmCC. Tumor stage on presentation was of limited value in predicting survival or response to treatment. Overall, the application of surgery yielded significantly better results (5-year DSS 52.2% versus 30.1%, p<0.001). In SNUC, radiotherapy was a beneficial supplement to surgery (5-year DSS 54.7% versus 15.7%, p=0.027), while radiotherapy as monotherapy performed poorly (5-year DSS 17.9%). Chemotherapy did not appear to contribute to survival. Based on these findings, we can conclude that the most important predictors of survival in SNC are differentiation grade and the associated choice of treatment modality. In contrast to other head and neck cancers, tumor staging appears of limited value in predicting survival or deciding on a treatment strategy. Surgery should be the cornerstone of treatment, supplemented by radiotherapy in poorly differentiated subtypes (SNUC, SmCC). Chemotherapy does not appear to contribute to survival.

SMARCA4 and SMARCA2 deficiency in non-small cell lung cancer: immunohistochemical survey of 316 consecutive specimens

The chromatin remodeling switch sucrose nonfermentable (SWI/SNF) complex has been increasingly implicated in the pathogenesis and dedifferentiation of neoplasms from several organs with prognostic and potential therapeutic implications. We herein investigated the expression of the SWI/SNF complex catalytic subunits SMARCA4 (BRG1) and SMARCA2 (BRM) in 316 consecutive non-small cell lung cancer (NSCLC) specimens on tissue microarrays (171 adenocarcinomas [ADCAs], 130 squamous cell carcinomas [SCCs], 9 adenosquamous carcinomas, and 6 large cell carcinomas) excluding undifferentiated/giant cell or rhabdoid carcinomas. Complete loss of SMARCA4 was observed in 8 (5.5%) of 146 evaluable pulmonary ADCAs and 6 (5.2%) of 115 evaluable pulmonary SCCs, whereas 9 (6.4%) of 140 ADCAs and 2 (1.7%) of 117 SCCs showed SMARCA2 loss. Two of 6 large cell carcinomas were SMARCA2 deficient. Concurrent loss of both markers was observed in 4 cases (2 ADCAs and 2 SCCs). Of 15 ADCAs with loss of either or both markers, 12 (80%) were TTF1 negative. In conclusion, SMARCA4 and SMARCA2 deficiency is observed in 5.1% and 4.8% of NSCLC, respectively. SMARCB1 expression was intact in all cases. The presence of differentiated histology (glandular or squamous) is a novel aspect among SWI/SNF-deficient carcinomas which in other organs generally are associated with undifferentiated/rhabdoid morphology. The predominance of TTF1 negativity among SWI/SNF-deficient pulmonary ADCA (80%) underlines the need to include these 2 markers in the evaluation of TTF1-negative ADCA of putative pulmonary origin. Given the recently documented potential of SMARCA4 loss as a predictor of chemosensitivity to platinum-based chemotherapy in NSCLC, recognition of the clinicopathological features of SMARCA4-deficient NSCLC in routine surgical pathology practice is recommended.

INI1 (SMARCB1)-Deficient Sinonasal Carcinoma: A Clinicopathologic Report of 2 Cases

Poorly differentiated sinonasal malignancies are amongst the hardest differential diagnoses in pathology, owing to the large number of rare entities that arise there. Complicating the matter is that most pathologists, including those with experience in head and neck pathology, have little experience in any one of these rare entities. Most patients with sinonasal carcinoma present with locally advanced disease and in the past a combination of chemotherapy, radiotherapy, and surgery would usually be recommended without the specific disease subtype playing a large part of the decision making. However, in the era of "precision medicine" and targeted therapies, the specific tumour subtype and an accurate diagnosis will become increasingly important even for the so-called "undifferentiated carcinoma". Specific entities that tend to enter into the differential diagnosis include olfactory neuroblastoma, sinonasal undifferentiated carcinoma (SNUC), and non-keratinizing squamous cell carcinoma (viral and non-viral). However, recent new entities, such as NUT-midline carcinoma also have to be considered. Recently it was found that a subset of tumours originally diagnosed as one of the aforementioned entities all demonstrated loss of the ubiquitously expressed protein Integrase Interactor 1 (INI1; SMARCB1). These tumours were often basaloid with at least partial rhabdoid differentiation and most were considered a part of the SNUC spectrum. In this report, we describe two additional cases of INI1-deficient sinonasal carcinoma prospectively identified, both of which appeared to have a marked response to neo-adjuvant chemoradiation, a finding not previously described.

Imaging Appearance of SMARCB1 (INI1)-Deficient Sinonasal Carcinoma: A Newly Described Sinonasal Malignancy

SMARCB1 (INI1)-deficient sinonasal carcinomas were first described in 2014, and this series of 17 cases represents the first imaging description. This tumor is part of a larger group of SMARCB1-deficient neoplasms, characterized by aggressive behavior and a rhabdoid cytopathologic appearance, that affect multiple anatomic sites. Clinical and imaging features overlap considerably with other aggressive sinonasal malignancies such as sinonasal undifferentiated carcinoma, which represents a common initial pathologic diagnosis in this entity. SMARCB1 (INI1)-deficient sinonasal tumors occurred most frequently in the nasoethmoidal region with invasion of the adjacent orbit and anterior cranial fossa. Avid contrast enhancement, intermediate to low T2 signal, and FDG avidity were frequent imaging features. Approximately half of the lesions demonstrated calcification, some with an unusual "hair on end" appearance, suggesting aggressive periosteal reaction.

Cytopathologic characteristics of SMARCB1 (INI-1) deficient sinonasal carcinoma: A potential diagnostic pitfall

Tumors of the head and neck are extremely diverse and a subset are poorly differentiated and difficult to classify. Recently, a new entity has been described with rhabdoid and/or plasmacytoid cytologic features and a characteristic genetic signature-inactivation of the SMARCB1 (INI-1) tumor suppressor gene. To date, only 16 cases of SMARCB1 (INI-1) deficient sinonasal carcinoma have been described, and there are currently no reports of the cytopathologic features by fine needle aspiration (FNA) cytology. A case of a 77-year-old man who presented with a posterior ethmoid sinus lesion with invasion into the skull base and bone was reported. FNA cytology of a right retropharyngeal lymph node revealed relatively monomorphic, loosely cohesive clusters of plasmacytoid cells with occasional nucleoli, rare intranuclear cytoplasmic inclusions, and mitotic figures in a background of necrosis and absence of overt squamous or glandular differentiation. A diagnosis of metastatic myoepithelial carcinoma was made; however, retrospectively, the surgical excision showed loss of the SMARCB1 (INI-1) tumor suppressor gene by immunohistochemistry. In summary, the cytomorphologic features of SMARCB1 (INI-1) deficient sinonasal carcinoma are relatively nonspecific and overlap with other regional tumors, including myoepithelial neoplasms. As a result, this entity should be considered in the differential diagnosis for a plasmacytoid tumor arising in the sinonasal tract by FNA cytology. Diagn. Cytopathol. 2016;44:700-703. © 2016 Wiley Periodicals, Inc.

Recently described neoplasms of the sinonasal tract

Surgical pathology of the sinonasal region (i.e., nasal cavity and the paranasal sinuses) is notoriously difficult, due in part to the remarkable diversity of neoplasms that may be encountered in this area. In addition, a number of neoplasms have been only recently described in the sinonasal tract, further compounding the difficulty for pathologists who are not yet familiar with them. This manuscript will review the clinicopathologic features of some of the recently described sinonasal tumor types: NUT midline carcinoma, HPV-related carcinoma with adenoid cystic-like features, SMARCB1 (INI-1) deficient sinonasal carcinoma, biphenotypic sinonasal sarcoma, and adamantinoma-like Ewing family tumor.