Newly Described Tumor Entities in Sinonasal Tract Pathology

Consolidation immunotherapy following concurrent chemoradiotherapy in a patient with sinonasal NUT carcinoma: a case report

Background

Nuclear protein in testis (NUT) cancers, also known as midline cancers, tends to occur in organs near the midline, such as the nasal sinuses and mediastinum. NUT carcinoma is very rare and has a poor prognosis.

Case description

We report the case of a 44-year-old female patient with sinonasal NUT carcinoma who presented with a soft tissue mass in the left frontal sinus, ethmoid sinus, and left nasal cavity on computed tomography; the tumor was poorly demarcated from the left rectus medialis. After discussion with a multidisciplinary team with expertise on head and neck tumors, the patient was considered inoperable, and definitive concurrent chemoradiotherapy (CCRT) was recommended. The patient underwent CCRT followed by three cycles of consolidation chemotherapy with albumin-bound paclitaxel and nedaplatin. Subsequently, the patient underwent 16 cycles of consolidation therapy with the programmed death-1 (PD-1) inhibitor tislelizumab. The immune-related adverse events included grade 2 hypothyroidism. After CCRT, consolidation chemotherapy, and consolidation immunotherapy, the patient achieved a favorable outcome. The patient survived for 31 months, and there were no signs of recurrence or metastasis during follow-up.

Conclusion

At present, there is no clear consensus on the consolidation treatment plan after CCRT for sinonasal NUT cancer. We used consolidation immunotherapy for the first time and achieved good efficacy, providing an innovative and promising treatment plan for refractory sinonasal NUT cancer.

Surgical treatment for uncommon malignancies of the paranasal sinuses and anterior cranial fossa: report of two cases and literature review

Malignant tumors of the nasal and paranasal cavities account for only 3-5% of all head and neck neoplasms. Among these tumors, rare instances of human papillomavirus (HPV)-positive multiphenotypic carcinomas and biphenotypic sarcomas have been documented. Two such cases are reported here, along with the respective treatment approaches. The first involved a 39-year-old male patient diagnosed with HPV-positive multiphenotypic carcinoma. Surgical treatment was performed through a craniofacial and transfacial approach, en bloc resection, and reconstruction of the anterior cranial base with a fascia lata graft and pericranial flap. The second involved a 41-year-old female patient diagnosed with biphenotypic sarcoma. Surgical treatment was performed through centripetal endoscopic tumour resection. In both cases, adjuvant radiotherapy was performed after obtaining the histopathological result and negative margins. Both patients were free of disease during postoperative follow-up. Given the rarity of these cases, there are no established guidelines outlining specific treatments. It is recommended that such tumours are assessed in interdisciplinary committees to determine the optimal treatment options. Typically, this will involve surgical resection via craniofacial and transfacial approaches or endoscopic surgery, depending on the diagnosis, extent of anatomical involvement, and tumour aggressiveness. Additionally, the potential benefits of adjuvant radiotherapy should be evaluated, as it has demonstrated promising outcomes, even in cases with positive margins.

Outcome-oriented clinicopathological reappraisal of sinonasal adenoid cystic carcinoma with broad morphological spectrum and high MYB::NFIB prevalence

Adenoid cystic carcinoma (AdCC) is a salivary gland neoplasm that infrequently appears in the sinonasal region. The aim of this study was to evaluate the outcome and clinicopathological parameters of sinonasal AdCC. A retrospective analysis was conducted on all cases of AdCC affecting the nasal cavity or paranasal sinuses between 2000 and 2018 at the University Hospital Zurich. Tumor material was examined for morphological features and analyzed for molecular alterations. A total of 14 patients were included. Mean age at presentation was 57.7 years. Sequencing revealed MYB::NFIB gene fusion in 11/12 analyzable cases. Poor prognostic factors were solid variant (p < 0.001), histopathological high-grade transformation (p < 0.001), and tumor involvement of the sphenoid sinus (p = 0.02). The median recurrence-free survival (RFS) and OS were 5.2 years and 11.3 years. The RFS rates at 1-, 5-, and 10-year were 100%, 53.8%, and 23.1%. The OS rates at 1-, 5-, and 10- years were 100%, 91.7%, and 62.9%, respectively. In Conclusion, the solid variant (solid portion > 30%), high-grade transformation, and sphenoid sinus involvement are negative prognostic factors for sinonasal AdCC. A high prevalence of MYB::NFIB gene fusion may help to correctly classify diagnostically challenging (e.g. metatypical) cases.

Nasal spindle cell tumor: A case report and literature review

BACKGROUND

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

KEY POINTS FROM THE CASE

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

MAIN LESSONS TO BE LEARNED FROM THIS CASE REPORT

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

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

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

Immunotherapy in SMARCB1 (INI-1)-deficient sinonasal carcinoma: Two case reports

BACKGROUND

SMARCB1/INI-1 deficient sinonasal carcinoma (SDSC) is a rare subset of sinonasal undifferentiated carcinoma with a poor prognosis. Here, we present two case reports of SDSC patients. We also review the literature on this tumor. This is the first published report of SDSC treatment with immunotherapy.

CASE SUMMARY

Here we present two patient cases of SDSC in which initial consultation and diagnosis were complicated but SDSC was ultimately diagnosed. One patient received a traditional treatment of surgery and adjuvant chemoradiotherapy, while the other patient received additional immunotherapy; the prognoses of these two patients differed. We review previous diagnostic literature reports and SDSC treatments and provide a unique perspective on this rare type of tumor.

CONCLUSION

SDSC is a rare, diagnostically challenging carcinoma with a consistently poor prognosis, early distant metastases, and frequent recurrence. Timely diagnosis and intervention are critical for treatment, for which the standard of care is surgery followed by adjuvant chemoradiotherapy, though immunotherapy may be an effective new treatment for SDSC.

Diagnostic algorithm for challenging blue cell sinonasal carcinoma

The newly emerging sinonasal carcinomas have demonstrated diverse morphologies and specific molecular rearrangements along with deviant clinical behavior from conventional counterparts. We aim to propose a diagnostic algorithm that is based on molecular findings of each sinonasal cancer and is considering the new entities has been called upon. Such a diagnostic algorithm should help diagnostic pathologists establish a diagnosis of a challenging sinonasal blue cell carcinomas and researchers performing retrospective analysis of archival cases. Along with consulting our archival cases, literature mining was conducted to retrieve the immunohistochemical and molecular findings regarding the newly emerging entities. Our proposed algorithm distinguishes poorly differentiated (non) keratinizing SNSCC, from anaplastic myoepithelial carcinoma, NUT midline carcinoma, SMARCB1/SMARCA4-deficient teratocarcinosarcoma, SMARCB1/SMARCA4-deficient carcinosarcoma, olfactory neuroblastoma, sinonasal undifferentiated carcinoma, HPV-related multiphenotypic sinonasal carcinoma and other adenocarcinomas. By incorporating morphologic features, immunohistochemical markers, and molecular investigations, the algorithm enhances the accuracy of diagnosis, particularly in cases where comprehensive molecular testing is not readily available. This algorithm serves as a valuable resource for pathologists, facilitating the proper diagnosis of sinonasal malignancies and guiding appropriate patient management.

Human papillomavirus-related multiphenotypic sinonasal carcinoma

Human papillomavirus-related multiphenotypic sinonasal carcinoma (HMSC) is a rare primary tumor of the sinonasal tract that has been reported recently. It is reportedly associated with human papillomavirus infection. The tumor presents with glandular cyst-like histology, but some cases exhibit squamous epithelialization and are positive on p16 immunohistochemical staining. The clinical picture and treatment of this disease have not been established. However, this report describes a recurrent case of this disease treated with salvage surgery. The patient was a 61-year-old woman who presented to the previous doctor with a chief complaint of nasal obstruction. A localized tumor was found in the left nasal cavity and was resected under endoscopic guidance. The postoperative pathological diagnosis was HMSC. Twenty-one months after the surgery, local recurrence was observed, and the patient was referred to our hospital. Since the recurrent lesion had widely infiltrated outside the nasal cavity, extensive resection and reconstructive surgery were performed. Postoperative radiotherapy was performed as an additional treatment. Notably, 13 months have passed since the salvage surgery, and no recurrence has been observed to date.

Clinical imaging of primary pulmonary nucleoprotein of the testis carcinoma

Objective

Primary pulmonary nucleoprotein of the testis (NUT) carcinoma is very rare in the clinic. In this study, the clinicopathological manifestations and imaging features of the primary pulmonary NUT carcinoma were investigated to improve the diagnosis of this disease.

Methods

Six patients with pathologically diagnosed pulmonary NUT carcinoma were analyzed, including three males and three females, aged 19-64 (49.00 ± 16.40) years, with clinical manifestations of cough in two cases, hoarseness in one case, blood in sputum in one case, chest pain in one case, and physical examination findings in one case, with a disease duration of 5 days to 4 months. The clinical and imaging data including CT and PET/CT were retrospectively analyzed. Further literature reviews were analyzed in both pulmonary and extrapulmonary NUT carcinoma cases who performed ¹⁸F-FDG PET/CT.

Results

Most of the patients with pulmonary NUT carcinomas presented as heterogeneous lobulated masses (83.33%), four cases (66.67%) were located in the upper lobe of the left lung, one case (16.67%) in the middle lobe of the right lung, and one case (16.67%) in the lower lobe of the right lung, with the maximum diameter ranging from 1.30 to 8.90 cm and the median of 3.55 cm, most of them were irregularly shaped, with more lobulated margins and more heterogeneous density (83.33%), and the enhancement was mild. PET/CT showed increased ¹⁸F-FDG uptake in the lesion and metastatic areas. Both the pulmonary NUT patients in this study and literature reviews showed the SUV_max of the tumor ranged from 5 to 40 with an average value of 12.8, whereas that of extrapulmonary lesions had a range of SUV_max at 4.5-64.1 and a mean of 13.8.

Conclusion

In patients with central lung masses, rapid disease progression, and poor response to initial treatment, the possibility of NUT cancer should be considered and anti-NUT monoclonal antibody immunohistochemical staining, combined with genetic detection, if necessary, should be performed as soon as possible. CT and PET/CT imaging are essential for the staging, management, treatment response assessment, and monitoring of pulmonary NUT cancer.

Texture analysis of conventional magnetic resonance imaging and diffusion-weighted imaging for distinguishing sinonasal non-Hodgkin's lymphoma from squamous cell carcinoma

PURPOSE

To evaluate the value of texture analysis (TA) of conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in the differential diagnosis between sinonasal non-Hodgkin's lymphoma (NHL) and squamous cell carcinoma (SCC).

METHODS

Forty-two patients with sinonasal SCC and 30 patients with NHL were retrospectively enrolled. TAs were performed on T2-weighted image (T2WI), apparent diffusion coefficient (ADC) and contrast-enhanced T1-weighted image (T1WI). Texture parameters, including mean value, skewness, kurtosis, entropy and uniformity were obtained and compared between sinonasal SCC and NHL groups. Receiver-operating characteristic (ROC) curves and logistic regression analyses were used to evaluate the diagnostic value and identify the independent TA parameters.

RESULTS

The mean value and entropy of ADC, and mean value of contrast-enhanced T1WI were significantly lower in the sinonasal NHL group than those in the SCC group (all P < 0.05). ROC analysis indicated that the entropy of ADC had the best diagnostic performance (AUC 0.832; Sensitivity 0.95; Specificity 0.67; Cutoff value 6.522). Logistic regression analysis showed that the entropy of ADC (P = 0.002, OR = 26.990) was the independent parameter for differentiating sinonasal NHL from SCC.

CONCLUSION

TA parameters of conventional MRI and DWI, particularly the entropy value of ADC, might be useful in the differentiating diagnosis between sinonasal NHL and SCC.

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

Objective

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

Methods

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

Results

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

Conclusions

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

Multimodality imaging and treatment of paranasal sinuses nuclear protein in testis carcinoma: A case report

BACKGROUND

Nuclear protein in testis (NUT) carcinoma is a rare aggressive malignant epithelial cell tumor, previously known as NUT midline carcinoma (NMC), characterized by an acquired rearrangement of the gene encoding NUT on chromosome 15q14. Due to the lack of characteristic pathological features, it is often underdiagnosed and misdiagnosed. A variety of methods can be used to diagnose NMC, including immunohistochemistry, karyotyping, fluorescence in situ hybridization, reverse transcription-polymerase chain reaction, and next-generation sequencing. So far, there is no standard treatment plan for NMC and the prognosis is poor, related to its rapid progression, easy recurrence, and unsatisfactory treatment outcome.

CASE SUMMARY

A 58-year-old female came to our hospital with a complaint of eye swelling and pain for 8 d. The diagnosis of NMC was confirmed after postoperative pathology and genetic testing. The patient developed nausea and vomiting, headache, and loss of vision in both eyes to blindness after surgery. Magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) performed after 1.5 mo postoperatively suggested tumor recurrence. The patient obtained remission after radiation therapy to some extent and after initial treatment with anti-angiogenic drugs and sonodynamic therapy (SDT), but cannot achieve long-term stability and eventually developed distant metastases, with an overall survival of only 17 mo.

CONCLUSION

For patients with rapidly progressing sinus tumors and poor response to initial treatment, the possibility of NMC should be considered and immunohistochemical staining with anti-NUT should be performed as soon as possible, combined with genetic testing if necessary. CT, MRI, and PET/CT imaging are essential for the staging, management, treatment response assessment and monitoring of NMC. This case is the first attempt to apply heat therapy and SDT in the treatment of NMC, unfortunately, the prognosis remained poor.

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.

NUT Midline Carcinoma: A Rare Solid Tumour Characterized by Chromosome Rearrangement

Objective

Rare and poorly differentiated NUT midline carcinoma (NMC) is a highly malignant tumour. However, due to the rarity of NMC, reports on its clinical, imaging, and pathologic features are still scarce.

Methods

In this study, three patients diagnosed with NMC located in the parotid gland, lung, and trachea were used as examples to summarize the clinicopathological features of NMC. All the cases were diagnosed by measuring positive nuclear reactivity to NUT antibody after dual-colour FISH tests were conducted, and all of the results were positive, indicating chromosomal rearrangements on 15q14 of the NUT gene.

Results

These three patients were treated with conventional treatments, including surgical therapy and chemoradiotherapy. Given the poor efficacy of intensive conventional treatment, two novel therapies, histone deacetylase inhibitors (HDACi) and bromodomain inhibitors (BETi) are recommended, as both can arrest the growth of tumour cells, and these targeted therapies may extend patient survival time in the future.

Conclusions

NMC is an easily misdiagnosed cancer with a poor prognosis; therefore, improving the awareness of clinicians is critical for increasing the diagnostic accuracy, and selecting effective treatment is the main method to improve prognosis.

Combined Neuroendocrine and Squamous Cell Carcinoma of the Sinonasal Tract: A Morphologic and Immunohistochemical Analysis and Review of Literature

Sinonasal malignancies constitute 3% of head and neck cancers, with squamous cell carcinoma (SCC) the most common histology. Neuroendocrine carcinomas (NEC) are rare, with a subset showing neuroendocrine carcinoma and a non-neuroendocrine component. The pathogenesis of these combined tumors is largely unknown, and TP53 driver mutations may play a role. A database search for combined NEC was performed across two institutions (UNM and UCSF) spanning 15 years. Excluding NUT midline carcinoma, 3 cases met inclusion criteria. All were morphologically NEC + SCC and underwent a comprehensive immunohistochemical evaluation. Tumors demonstrated two components histologically: moderately to poorly differentiated SCC and high-grade NEC. Divergent differentiation was confirmed with lineage-specific markers. Only one patient received neoadjuvant chemotherapy prior to surgery, with a remarkable response (a marked decrease in the size of the primary lesion and resolution of liver metastases). Immunohistochemical staining for p53 was increased in 2 of 3 cases (both components), suggesting a role in the carcinogenesis of these tumors. Aberrant expression of beta-catenin was not identified. One case tested positive for p16, which can be seen in high grade NECs due to inactivation of Rb gene. Additionally, both cases with a small cell NEC component expressed PD-L1, suggesting that immunotherapy may be an effective treatment. Findings in this study support the role of p53 mutation in a subset of combined NEC + SCC of the sinonasal tract. Recognition of this rare entity is essential for optimal management of these aggressive neoplasms.

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.

High Grade Myoepithelial Carcinoma of Maxillary Sinus with Extensive Rhabdoid Differentiation and INI-1 Loss: Expanding the Histopathological Spectrum of Sinonasal Carcinoma

Myoepithelial carcinoma (MEC) of salivary gland is an uncommon tumor with no specific age or sex predilection. Most of the cases (~90%) arise in parotid and submandibular glands followed by palate. MEC of maxillary sinus is rare. We describe an extremely rare case of high grade MEC with rhabdoid differentiation and INI-1 loss involving maxillary sinus of an elderly male.

DEK-AFF2 Carcinoma of the Sinonasal Region and Skull Base: Detailed Clinicopathologic Characterization of a Distinctive Entity

A novel DEK-AFF2 fusion was recently reported in 4 nonkeratinizing squamous cell carcinomas of the sinonasal region and skull base, including 1 with exceptional response to immunotherapy, but it is not yet clear if this rearrangement defines a unique clinicopathologic category or represents a rare event. This study aims to characterize a larger cohort of carcinomas with DEK-AFF2 fusions to assess whether they truly constitute a distinctive entity. Among 27 sinonasal and skull base nonkeratinizing squamous cell carcinoma that were negative for human papillomavirus and Epstein-Barr virus, RNA sequencing identified DEK-AFF2 fusions in 13 cases (48%). Nine were centered in the nasal cavity, 2 in the middle ear/temporal bone, 1 in the nasopharynx, and 1 in the orbit. These tumors displayed recurrent histologic features including (1) complex endophytic and exophytic, frequently papilloma-like growth, (2) transitional epithelium with eosinophilic to amphophilic cytoplasm, (3) absent or minimal keratinization with occasional compact keratin pearls, (4) monotonous nuclei, and (5) prominent tumor-infiltrating neutrophils or stromal lymphocytes. This appearance not only overlaps with high-grade basaloid sinonasal carcinomas but also with benign papillomas and tumors reported as low-grade papillary Schneiderian carcinoma. However, DEK-AFF2 carcinomas showed frequent local recurrence, cervical lymph node metastases, and distant metastasis with 2 deaths from disease, confirming they are aggressive malignancies despite relatively bland histology. Overall, the distinctive molecular, histologic, and clinical features of DEK-AFF2 carcinomas suggest they represent a unique entity in the sinonasal region. This tumor merits increased pathologic recognition to better understand its prognostic and therapeutic implications.

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

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

Primary and Secondary/ Metastatic Salivary Duct Carcinoma Presenting within the Sinonasal Tract

Traditionally, sinonasal adenocarcinomas have been subdivided into intestinal (ITAC) and non-intestinal (non-ITAC) categories. The latter encompasses salivary-type adenocarcinomas originating from the seromucinous glands of the sinonasal mucosa and non-salivary adenocarcinomas. The non-salivary adenocarcinoma category is further subdivided into low-and high-grade variants. Among salivary-type sinonasal adenocarcinomas, tumors recapitulating salivary duct carcinoma (SDC) are exceedingly rare, but some might have been lumped into the high-grade non-ITAC category. To date, only three primary SDCs originating in the sinonasal tract have been reported. We herein describe 7 cases of SDC including one previously reported case (4 primary sinonasal, 3 metastatic/ extension from parotid gland SDC). The primary tumors affected 3 males and one female aged 60 - 75. Different sites were involved by the primary tumors while the secondary tumors affected the sphenoidal (2) and the frontal + maxillary (1) sinuses. Three primary tumors were de novo high-grade SDC and one was confined to contours of a pre-existing pleomorphic adenoma. All 3 secondary tumors were SDC ex pleomorphic adenoma of the parotid with a long history of recurrences, ultimately involving the sinonasal tract. Androgen receptor was positive in 7/7 cases. Four of 6 cases were strongly HER2/neu + (either score 3 + or with verified amplification). This small case series adds to the delineation of primary sinonasal SDC highlighting that almost half of invasive SDC presenting within sinonasal tract indeed represents extension or metastasis from a parotid gland primary. There is a tendency towards overrepresentation of HER2/neu-positive cases in both categories (primary and metastatic), but this needs clarification in larger studies.

SMARCA4-deficient Sinonasal Carcinoma: A Series of 10 Cases Expanding the Genetic Spectrum of SWI/SNF-driven Sinonasal Malignancies

The molecular pathogenesis of poorly differentiated sinonasal carcinoma received significant attention in recent years. As a consequence, several unclassified carcinomas in the morphologic spectrum of sinonasal undifferentiated carcinoma have been reclassified as distinctive genetically defined variants or entities. Among the latter are NUT-rearranged carcinoma and SMARCB1-deficient carcinomas. In this study, we further characterize a rare variant of sinonasal undifferentiated carcinoma-like tumors characterized by inactivation of the SWItch/Sucrose Nonfermentable chromatin remodeler SMARCA4 (BRG1) detectable by immunohistochemistry. Patients were 7 males and 3 females aged 20 to 67 years (median, 44). Tumors originated in the nasal cavity (6), nose and sinuses (2), or at unspecified site (2). Six tumors were initially misdiagnosed as small cell neuroendocrine carcinoma (SCNEC) or large cell neuroendocrine carcinoma (LCNEC). Histologically, the tumors were composed of small basaloid (3 cases) or large epithelioid (7) cells disposed into nests and solid sheets with extensive areas of necrosis. No glands or other differentiating features were noted. Abortive rosettes were seen in 1 case. Immunohistochemistry showed consistent expression of pankeratin and absence of CK5, p63, p16, and NUT in all tumors tested. Other tested markers were variably positive: CK7 (2/6), synaptophysin (9/10; mostly focal and weak), chromogranin-A (4/10; focal), and CD56 (3/5; focal). All tumors showed total loss of SMARCA4 and retained expression of SMARCB1/INI1. Co-loss of SMARCA2 was seen in 1 of 8 cases. Limited data were available on treatment and follow-up. Two patients received surgery (1 also radiotherapy) and 3 received chemotherapy. Metastases (cervical nodes, liver, bone, and lung/mediastinal) were detected in 3 patients; 2 were alive under palliative chemotherapy at 8 and 9 months while 1 died of progressive lung disease at 7 months. Three patients (1 with brain invasion) died soon after diagnosis (1 to 3 mo). In total, 4 of 6 patients (66%) with follow-up died of disease (median, 3 mo). This series characterizes SMARCA4-deficient sinonasal carcinoma as a genetically distinct aggressive entity in the spectrum of undifferentiated sinonasal carcinomas. These variants add to the spectrum of SWItch/Sucrose Nonfermentable-deficient sinonasal carcinomas, at the same time expanding the topographic distribution of SMARCA4-related malignancies.

SMARCB1 (Integrase Interactor 1)-Deficient Sinonasal Carcinoma of the Maxillary Sinus: A Newly Described Sinonasal Neoplasm

SMARCB1 (integrase interactor 1) is a tumor suppressor gene encoded on chromosome 22q11.2 that encodes a core subunit of SWI/SNF chromatin remodeling complexes and plays a critical role in regulating gene expression and chromatin structure. We describe a case of SMARCB1 (integrase interactor 1)-deficient sinonasal carcinoma of the left maxillary sinus in a 63-year-old woman with an initial presentation of numbness of the maxillary teeth and facial swelling.

Primary papillary epithelial tumour of the sella: expanding the spectrum of TTF-1-positive sellar lesions

AIM

To describe four novel primary epithelial tumours of the sella with papillary architecture and Thyroid Transcription Factor 1 (TTF-1) expression.

METHODS

Paraffin-embedded tissue from the four cases and recurrence of patient 1 was investigated with haematoxylin-eosin, special histochemical stains, immunohistochemistry with a broad panel of antibodies and next-generation sequencing. The ultrastructure of one tumour was studied in tissue retrieved from paraffin.

RESULTS

The lesions occurred in three females aged 20, 26 and 42 years and a male aged 49 years. They presented with signs and symptoms secondary to pituitary stalk compression. Preoperative neuroimaging documented mixed solid and cystic, enhancing sellar masses with suprasellar extension. Histologically, the tumours showed thin papillae lined by a single layer of cytokeratin and TTF-1-positive cuboidal and cylindrical cells with mildly atypical nucleus. Next-generation sequencing performed in three cases did not identify any mutations. The main differential diagnosis included metastasis from lung or thyroid carcinoma, extraventricular choroid plexus papilloma and sellar ependymoma.

CONCLUSION

We suggest the descriptive term of primary papillary epithelial tumour of the sella (PPETS) for this entity and propose that it could represent the intracranial equivalent of thyroid-like low-grade nasopharyngeal papillary adenocarcinoma. The cell of origin of PPETS remains undetermined although the intense and ubiquitous expression of TTF-1 may suggest a derivation from the infundibulum or ventricular recess. Our study expands the spectrum of sellar TTF-1-positive tumour and challenges the view that they all derive from pituicytes.

Variable Expression of S100 Protein in Sinonasal Malignant Mucosal Melanoma: A Potential Diagnostic Pitfall

Sinonasal malignant mucosal melanoma (SNM) is a rare, aggressive malignancy. The diagnosis of SNM is often quite challenging due to anatomical limitations, frequent lack of pigmentation, variable histologic appearances, and aberrant differentiation (e.g., positivity for cytokeratin, desmin, or neuroendocrine markers). S100 protein is routinely used as a standard screening marker for SNM, but it may lack optimal sensitivity. Our objective was to study the extent of immunohistochemical expression of S100 protein in SNM, and determine its diagnostic value by comparing it to a newer melanoma marker, SOX10. Twenty-three cases of sinonasal MMM were retrieved from the archival files of the Department of Pathology at UT Southwestern Medical Center. The patients included 14 men and 9 women, and ranged from 36 to 90 years (mean 64.9 years). Sections from blocks of formalin-fixed, paraffin-embedded tissue were used for immunohistochemical analysis with S100 protein and SOX10. The extent and intensity of immunostaining was recorded, and H-score was calculated. For a subset of negative or focally positive cases, S100 protein was repeated at a high-volume reference laboratory. S100 protein immunoexpression was quite variable in the SNM cases, with H-scores ranging from 0 to 300 (mean 123). While 11 of 23 cases exhibited strong and diffuse staining (H-score > 100) as expected for melanoma, 7 were weak and/or focal (H-score 1-100), and 5 were completely S100 protein-negative. For 10 cases, the negative or focal results were confirmed by reference laboratory staining. In contrast, all 23 SNM cases were diffusely and strongly positive for SOX10 (H-scores 210-300, mean 296). Our study demonstrated that S100 protein immunoexpression is extremely variable in SNM. Weak or even absent S100 protein staining is not uncommon in SNM, and should not dissuade pathologists from that diagnosis. Our data demonstrates that S100 protein is insufficiently sensitive to be used as a screening marker for SNM, but that SOX10 is consistently and robustly positive, and should therefore replace S100 protein for that purpose. Indeed, for any high-grade sinonasal tumor, pathologists must have a low threshold for utilizing additional markers to exclude the possibility of SNM.

Clinical management of emerging sinonasal malignancies

Several emerging sinonasal malignancies have recently been described in the pathology literature. Although not all distinctly classified by the World Health Organization, these rare tumors present a management challenge to surgeons and oncologists. While prior studies have summarized histologic details, a clinically focused review is currently lacking in the literature. This review describes the presentation, histopathology, imaging, treatment, and prognosis of newly described or recently evolving sinonasal malignancies while highlighting the distinguishing features of these entities. It includes teratocarcinosarcoma, human papillomavirus-related multiphenotypic carcinoma, biphenotypic sinonasal sarcoma, sinonasal renal cell-like adenocarcinoma, NUT-midline carcinoma, squamous cell carcinoma associated with inverted papilloma, sinonasal undifferentiated carcinoma, and INI-1-deficient sinonasal carcinoma. By describing the diagnosis, treatment, and prognosis of these recently defined entities, this clinical review aims to help guide oncologists in the clinical management of these patients.

Sinonasal cancer: an overview of the emerging subtypes

BACKGROUND

Advances in immunohistochemistry have spearheaded major developments in our understanding and classification of sinonasal tumours. In the last decade, several new distinct histopathological entities of sinonasal cancer have been characterised.

OBJECTIVES

This review aims to provide a clinical update of the major emerging subtypes for the ENT surgeon and an overview of the management strategies available for this heterogeneous group of pathologies.

CONCLUSION

Although rare, knowledge of sinonasal neoplasm subtypes has implications for prognosis, treatment strategies and the development of novel therapeutic targets.

Renal Metastases from a Nasal Cavity Mixed Squamous Cell and Adenoid Cystic Carcinoma: A Case Report

Patient: Female, 64-year-old

Final Diagnosis: Renal metastases from a nasal cavity mixte • squamous cells and adenoid cystic • carcinoma

Symptoms: Epistaxis

Medication: —

Clinical Procedure: —

Specialty: Oncology

Management of sinonasal adenocarcinomas with anterior skull base extension

INTRODUCTION

Sinonasal adenocarcinomas (SNAC) are rare and heterogeneous. Management of SNAC follows a rather standardized and internationally accepted paradigm. Several refinements have been introduced during the last decade.

METHODS

A narrative review of most updated literature on SNACs has been conducted.

RESULTS

SNACs are classified as intestinal-type and non-intestinal-type, which are further categorized according to grade. Preoperative work-up should include magnetic resonance imaging (or contrast-enhanced computed tomography as a secondary or complementary choice) and biopsy under general anesthesia, or under local anesthesia in case of a history of exposure to wood and/or leather dust. Positron emission tomography, neck ultrasound, and fine-needle aspiration cytology are indicated in selected cases. Surgery represents the most common upfront modality of treatment and is usually accomplished via a transnasal endoscopic approach. Adjuvant radiation therapy is indicated for high-grade, locally advanced tumors and/or in case of margins involvement. Neoadjuvant chemotherapy with cisplatin, 5-fluorouracil and leucovorin may offer high response rates and long-term control in a subgroup of patients affected by intestinal-type adenocarcinoma, and in particular in those whose tumors harbor a functional p53 protein. Most of the bio- and immune-therapeutic potentials on SNACs still remain theoretical, and no clinical data are currently available.

CONCLUSIONS

Management of SNAC consists of histological diagnosis, radiological staging, radical surgery, and adjuvant radiation therapy. Neoadjuvant chemotherapy can be indicated in selected cases. The role of biotherapy and immune therapy still needs to be elucidated.

Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma: A Recent Discovery. A Case Report and Literature Review

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma is a distinct, recently described neoplasm of salivary gland nature that has an unusual microscopic appearance exhibiting multidirectional differentiation. Originally described by Bishop et al. in 2012, this distinct form of head and neck cancer is a very rare entity that few pathologists have encountered in practice, and only 50 cases have been reported in the literature. It usually presents as a large, destructive mass confined to the nasal cavity or paranasal sinuses, and is always associated with high-risk HPV infection. Although histologically it often resembles adenoid cystic carcinoma, this neoplasm also consistently exhibits features of myoepithelial, ductal and squamous differentiation. Newly recognized characteristics have recently been described that include bizarre pleomorphism, sarcomatoid transformation, and heterologous cartilaginous differentiation. These unique features have continued to expand the morphologic spectrum of this neoplasm and justify the recent change in its nomenclature from "HPV-related carcinoma with adenoid cystic-like features" to "HPV-related multiphenotypic sinonasal carcinoma (HMSC)". In 2017, "HPV-related carcinoma with adenoid cystic like features" was included as a provisional tumor type by the World Health Organization Classification of Head and Neck Tumors. Despite the presence of high-grade histologic characteristics such as necrosis and brisk mitotic activity, and a tendency for recurrence, HMSC demonstrates indolent clinical behavior and carries a good prognosis.

Diagnostic traps awaiting the head/neck pathologist: "Cytoplasm-poor" neoplasms

CONTEXT

Beyond squamous carcinoma, a variety of diagnostically challenging neoplasms arise within various head and neck sites. This is particularly the situation with neoplasms where little cellular cytoplasm is present to assist the pathologist in categorizing such lesions.

OBJECTIVE

To highlight diagnostic pitfalls that accompanying neoplasms composed primarily of 'cytoplasmically-poor' cells. These pitfalls include morphologic and immunohistochemical traps that emerge from this class of neoplasms.

DATA SOURCES

Selection of pathologic specimens from the author's personal files, and literature review.

CONCLUSIONS

Interpretative pitfalls regarding the histopathology and immunophenotype of small 'cytoplasmically-poor' neoplasms are a diagnostic hazard in head and neck surgical pathology practice, and require knowledge of histomorphologic plasticity and aberrant immunophenotyping.

Mammary Analog Secretory Carcinoma of the Nasal Cavity: Characterization of 2 Cases and Their Distinction From Other Low-grade Sinonasal Adenocarcinomas

Secretory carcinoma, originally described as mammary analog secretory carcinoma (MASC), is a low-grade salivary gland tumor characterized by a t(12;15)(p13;q25) translocation, resulting in an ETV6-NTRK3 gene fusion. Most MASCs are localized to the parotid gland and intraoral minor salivary glands. Moreover, ETV6-rearranged carcinomas with secretory features have been reported recently in the thyroid (with and without a history of radiation exposure), skin, and in very rare instances in the sinonasal tract. Here, we describe 2 cases of primary MASC in the sinonasal tract and provide a detailed clinical and histopathologic characterization of their morphology, immunohistochemical profile, and genetic background and highlight features allowing for its separation from its recently described molecular mimicker, ETV6-rearranged low-grade sinonasal adenocarcinoma.

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.

SMARCB1-Deficient Sinonasal Carcinoma: A Case Report and Discussion of the Clinical Implications

OBJECTIVE

SMARCB1-deficient sinonasal tract carcinomas are an emerging subset of rare tumors recently described in the literature, with less than 100 reported cases. Given the aggressive nature of this tumor, timely diagnosis is especially important. We present a case report of a SMARCB1-deficient carcinoma of the sinonasal tract.

METHODS

Case report with review of the literature.

RESULTS

The patient was a 53-year-old male with computed tomography (CT)-proven mass of the right ethmoid and sphenoid sinuses. Rigid nasal endoscopy revealed a purple mass completely obstructing the right nasal cavity that extended inferiorly from the posterior ethmoids and sphenoid sinuses. Initial biopsy in the emergency room was nondiagnostic due to extensive tumor necrosis. Magnetic resonance imaging (MRI) revealed T2 hypointense enhancing mass centered in the right posterior ethmoids with invasion into the right orbital apex, classifying it as a T4b tumor. The patient underwent repeat biopsy with frozen section and tumor debulking. Immunohistochemical analysis of subsequent biopsy revealed complete loss of INI-1 and negative staining for other pertinent markers, alluding to the diagnosis of SMARCB1-deficient sinonasal tract carcinoma.

CONCLUSION

Tumor necrosis may be problematic in obtaining a diagnosis for SMARCB1-deficient sinonasal carcinomas. Thus, sampling various regions of the tumor during initial biopsy can prevent delays in diagnosis and treatment.

Human Papillomavirus-Related Carcinoma With Adenoid Cystic-like Features of the Sinonasal Tract (Also Known as Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma)

Human papillomavirus (HPV)-related carcinoma with adenoid cystic-like features is a rare, recently recognized entity restricted to the sinonasal tract. By definition, it is associated with high-risk HPV infection, particularly with HPV type 33. In most cases, tumors are composed of dual cell populations, including predominant basaloid myoepithelial cells and usually inconspicuous ductal cells. Solid components with focal cribriform or tubular patterns, abrupt keratinization within tumor nests, and squamous dysplasia of the surface epithelium are characteristics of HPV-related carcinoma with adenoid cystic-like features. The immunohistochemistry of p16 followed by high-risk HPV testing may help in the differential diagnosis. Recent studies have demonstrated that the morphologic features of this entity are more diverse than initially believed. Surgical resection is the prime alternative for treatment. According to the limited data, the prognosis of this disease may be better than that of other sinonasal carcinomas.

High-Grade Sinonasal Carcinoma: Classification Through Molecular Profiling

High-grade sinonasal carcinomas are a cohort of malignant epithelial neoplasms arising in the sinonasal cavities with distinct, ominous morphologic features or lacking well-differentiated features that might otherwise classify them as less biologically worrisome. Recent advances in molecular profiling have led to the identification of several distinct tumor entities previously grouped together. These molecularly distinct lesions include NUT (midline) carcinoma, INI1 (SMARCB1)-deficient carcinoma, SMARCA4-deficient sinonasal carcinoma, and novel IDH-mutant sinonasal undifferentiated carcinoma, in addition to the previously described lymphoepithelial carcinoma that may also be included in the differential diagnosis. The discovery of these distinct molecular tumor profiles may have significant clinical impact as targeted molecular-based therapeutics continue to evolve, and they may offer some respite for patients who have these highly aggressive cancers.

Clinical Utility of In Situ Hybridization Assays in Head and Neck Neoplasms

Head and neck pathology present a unique set of challenges including the morphological diversity of the neoplasms and presentation of metastases of unknown primary origin. The detection of human papillomavirus and Epstein-Barr virus associated with squamous cell carcinoma and newer entities like HPV-related carcinoma with adenoid cystic like features have critical prognostic and management implications. In salivary gland neoplasms, differential diagnoses can be broad and include non-neoplastic conditions as well as benign and malignant neoplasms. The detection of specific gene rearrangements can be immensely helpful in reaching the diagnosis in pleomorphic adenoma, mucoepidermoid carcinoma, secretory carcinoma, hyalinizing clear cell carcinoma and adenoid cystic carcinoma. Furthermore, molecular techniques are essential in diagnosis of small round blue cell neoplasms and spindle cell neoplasms including Ewing sarcoma, rhabdomyosarcoma, synovial sarcoma, biphenotypic sinonasal sarcoma, dermatofibrosarcoma protuberans, nodular fasciitis and inflammatory myofibroblastic tumor. The detection of genetic rearrangements is also important in lymphomas particularly in identifying 'double-hit' and 'triple-hit' lymphomas in diffuse large B cell lymphoma. This article reviews the use of in situ hybridization in the diagnosis of these neoplasms.

Biphenotypic sinonasal sarcoma: demographics, clinicopathological characteristics, molecular features, and prognosis of a recently described entity

Biphenotypic sinonasal sarcoma (BSNS) is a recently recognized type of sarcoma arising exclusively in the sinonasal tract displaying unique clinical course, histopathology, and genetics. Due to its rarity, only case series and case reports are available. In order to provide an overview of the current understanding of this disease, we present a comprehensive review of the literature and present three previously unreported cases of BSNS. A total of 55 genetically characterized and 41 cases without molecular data were identified in the literature. Two-thirds of patients were female and the peak incidence was in the fifth decade. Fatal outcome was rare (two cases with intracranial extension) and local recurrence occurred in 31.6%, all occurring within 5 years after initial treatment. Histologically, BSNS is highly cellular in the majority of cases and composed of fascicles of spindle cells, with entrapped hyperplastic surface epithelium being a frequent finding. The immunohistochemical profile is characteristic due to the biphasic nature of this lesion, with shared features of both myogenic and neural origin. Rhabdomyoblastic differentiation is apparent in a subset of cases. The most common genetic event is the PAX3-MAML3 fusion (58.6%) but isolated PAX3 rearrangement (19.2%), absence of rearrangements (9.1%), PAX3-FOXO1 (8.1%), PAX3-NCOA1 (4%), and isolated MAML3 rearrangement (2%) have also been reported. In conclusion, the recognition of BSNS is crucial due to its relatively indolent clinical course. A selected immunohistochemical panel and/or molecular confirmation can be used to aid in appropriate diagnosis and consequently in prognostication and to avoid overtreatment with chemotherapy regimens used in its mimics.

Strong SOX10 expression in human papillomavirus-related multiphenotypic sinonasal carcinoma: report of 6 new cases validated by high-risk human papillomavirus mRNA in situ hybridization test

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is associated with high-risk HPV (HR-HPV) infection. Using HR-HPV messenger RNA (mRNA) in situ hybridization (ISH), we reported 6 new HMSC cases and compared their histopathology with that of sinonasal adenoid cystic carcinoma. Using p16 immunohistochemistry (IHC) and HR-HPV ISH, we retrospectively identified 6 HMSC cases. All HMSC cases were positive for HR-HPV mRNA ISH and p16 IHC. Two HMSC cases had overlying atypical squamous epithelium, and 1 had invasive squamous cell carcinoma (SCC). All HMSC cases were SOX10 positive, whereas the overlying atypical squamous epithelium and the SCC were SOX10 negative. One atypical HMSC-like case was also identified, which was positive for HR-HPV mRNA ISH, HR-HPV DNA ISH, and SOX10 IHC, but negative for p16 IHC. This study showed that HR-HPV mRNA ISH was a useful tool to diagnose HMSC and had stronger signals compared with HR-HPV DNA ISH. HR-HPV E6/E7 mRNA could be identified in the overlying atypical squamous epithelium and the invasive SCC. A combination of p16 and SOX10 IHC will be a useful screening panel for HMSC followed by confirmatory HR-HPV mRNA ISH test.

Differential Diagnosis of Sinonasal Lymphoma and Squamous Cell Carcinoma on CT, MRI, and PET/CT

Objective The purpose of this study was to analyze computed tomography (CT) and magnetic resonance (MR) images and to evaluate the maximum standardized uptake value (SUV max) of positron emission tomography (PET)/CT parameters between sinonasal non-Hodgkin's lymphoma (NHL) and squamous cell carcinoma (SCC), knowing the imaging features that distinguish sinonasal NHL from SCC. Study Design Case series with chart review. Setting University tertiary care facility. Subjects and Methods We analyzed the features on CT, MR imaging, and PET/CT of 78 patients diagnosed with sinonasal NHL or SCC histopathologically. The CT (n = 34), MRI (n = 25), and PET/CT (n = 33) images of 39 patients with sinonasal NHL and the CT (n = 38), MR (n = 28), and PET/CT (n = 31) images of 39 patients with SCC were evaluated. The sinonasal NHL was diagnosed as natural killer/T-cell lymphoma (n = 28) and diffuse large B-cell lymphoma (n = 11). Results Patients with sinonasal NHL had a larger tumor volume and higher tumor homogeneity than patients with SCC on T2-weighted and postcontrast MR images. Most of the sinonasal NHL and SCC showed a high degree of enhancement. The apparent diffusion coefficient (ADC) values and adjacent bone destruction were significantly lower in sinonasal NHL than in SCC. However, cervical lymphadenopathy, Waldeyer's ring involvement, and PET/CT SUV max showed no significant differences between sinonasal NHL and SCC. Conclusion CT and MR images of sinonasal masses showing a bulky lesion, marked homogeneity, and low ADC values without adjacent bone destruction are more suggestive of sinonasal NHL than SCC.

Biphenotypic sinonasal sarcoma: A series of six cases with evaluation of role of β-catenin immunohistochemistry in differential diagnosis

INTRODUCTION

Biphenotypic sinonasal sarcoma (BSNS) is a recently described mesenchymal tumor exclusive to the sinonasal region. It is a low grade sarcoma, displaying evidence of myogenic and neural differentiation. Role of β-catenin immunohistochemistry in distinguishing it from its morphological mimics is not well-established. We conducted this study to identify cases of BSNS from our archives, and to examine immunopositivity for β-catenin in them as well as in its close differential diagnosis.

METHODS

All cases of nasal cavity and paranasal sinus mesenchymal neoplasms were identified. Histopathological features were reviewed. Cases showing smooth muscle actin (SMA) and S-100 immunopositivity, and typical morphology were reclassified as BSNS. β-catenin immunoexpression was assessed.

RESULTS

Twenty-one mesenchymal tumors, including 12 sinonasal hemangiopericytoma (SNHPC), five solitary fibrous tumors (SFT), three BSNS, and one synovial sarcoma were identified. Three SNHPC cases were reclassified as BSNS. BSNS patients included one male and five females, with mean age of 51years. Five BSNS cases (83.3%) showed nuclear β-catenin immunopositivity. SNHPC cases also were β-catenin positive (60%).

CONCLUSION

BSNS is a rare sinonasal neoplasm, frequently misdiagnosed as SNHPC and SFT. β-catenin immunopositivity is seen in majority of cases, indicating a role in pathogenesis. However, due to positivity in other tumors like SNHPC, it has limited role in differential diagnosis.

ETV6 Gene Rearrangements Characterize a Morphologically Distinct Subset of Sinonasal Low-grade Non-intestinal-type Adenocarcinoma: A Novel Translocation-associated Carcinoma Restricted to the Sinonasal Tract

Low-grade sinonasal adenocarcinomas (low-grade SNACs) of the sinonasal tract comprise a poorly characterized and histologically heterogeneous group of tumors. We describe three cases of a histologically distinct variant of low-grade SNAC characterized by ETV6 gene rearrangements. The patients included 2 women (aged 32 and 88 y) and a man (aged 75 y); all were initially treated with surgery alone. Follow-up ranged from 9 to 170 months with one patient having 2 local recurrences and none experiencing distant or regional metastases. Tumors were composed of cytologically bland columnar and cuboidal eosinophilic tumor cells with basally located nuclei arranged in tubular and tubulotrabecular patterns. Immunohistochemically, CK7, DOG1, GCDFP-15, and SOX10 were positive in all cases, and vimentin was positive in 2 cases. Scattered single cells or small groups of tumor cells were S-100 positive. Only one case had weak, focal expression of GATA3, and mammaglobin was consistently negative. Two cases had ETV6-NTRK3 gene fusions, whereas ETV6 had an unknown fusion partner gene in one case. The highly similar morphology, immunohistochemical profile, and genetics of the presented cases are suggestive of a specific disease. Although translocation-associated adenocarcinomas in the sinonasal tract have previously been described exclusively as salivary-type carcinomas, we present the first type of carcinoma characterized by recurrent genetic rearrangements and distinct phenotype occurring exclusively in the sinonasal tract with no known major salivary gland counterpart. We provisionally designate this tumor ETV6-rearranged low-grade SNAC. Identification of additional cases is necessary to fully appreciate the morphologic and biological spectrum of this disease.

Sinonasal NUT carcinoma: clinicopathological and cytogenetic analysis with autopsy findings

Nuclear protein in testis (NUT) carcinoma is a rare malignant neoplasm with an undifferentiated morphology. Its diagnosis is often difficult, especially as the sinonasal tract gives rise to many tumors with undifferentiated morphologies. Not many cases of sinonasal NUT carcinomas have been reported, and its clinicopathological features have not been sufficiently clarified. In this study, we performed a clinicopathological study of 4 patients with sinonasal NUT carcinoma, including wide-ranging immunohistochemical tests and cytogenetic analyses using fluorescence in situ hybridization and DNA sequencing. Autopsy findings were obtained from 2 patients. Patients' ages ranged from 9 months to 66 years (median, 37 years). Three cases involved the nasal cavity; of these, 2 also involved the ethmoid sinus. One case only involved the frontal sinus. Histologically, all cases revealed undifferentiated small round cell morphology and necrosis with indistinct cell borders, vesicular chromatin, and distinct nucleoli. All patients received chemoradiotherapy; 3 died of disease 10 to 15 months after their diagnoses, while one was lost to follow-up. The 2 autopsied patients showed multiorgan metastases; interestingly, one showed cartilaginous differentiation in a metastatic lesion. Immunohistochemically, all cases were diffusely positive for NUT, p63, and Myc, and were focal for p40. The cells variably expressed epithelial markers, and CD34 was positive in one patient. Cytogenetically, all showed BRD4-NUT fusion genes, but one had a different breakpoint in each exon. Finally, a literature review indicated that sinonasal NUT carcinoma tends to involve frontal and ethmoidal sinuses more frequently than other sinonasal cancers.

Renal cell -like carcinoma of the nasal cavity: a case report and review of the literature

Background

Sinonasal renal cell-like carcinoma (SRCLC) is an extremely rare low malignant tumor arising in the sinonasal tract, with histological mimicry of renal cell carcinoma.

Case presentation

We present a case of sinonasal renal cell-like carcinoma in a 63-year-old male patient. Computer tomography(CT) scanning revealed a soft tissue mass at the left nasal cavity and choana. Histologically, the predominant tumor architecture was follicular to glandular with intervening fibrous septa. The tumor cells were uniform cuboidal to polyhedral with abundant clear or eosinophilic cytoplasm. Immunohistochemically, the tumor cells were strongly positive for CK7, EMA, vimentin, SOX10, S-100, and focally positive for CA9. During 6 months of follow-up, there was no clinical or radiological evidence of recurrence or metastasis.

Conclusion

SRCLC has microscopic features which overlap with tumors that contain clear cells. Thus, several other tumors must be considered in the differential diagnosis of a tumor of the sinonasal region with clear cells, especially metastatic renal clear cell carcinoma. SRCLC is an indolent tumor and none of the reported SRCLC patients had metastatic disease.

Sinonasal Tract Alveolar Rhabdomyosarcoma in Adults: A Clinicopathologic and Immunophenotypic Study of Fifty-Two Cases with Emphasis on Epithelial Immunoreactivity

Sinonasal tract (SNT) alveolar rhabdomyosarcoma (ARMS) are frequently misdiagnosed, especially in adults. Fifty-two adult (≥18 years) patients with SNT ARMS were reviewed and characterized by immunohistochemistry and molecular studies. Twenty-six females and 26 males (18-72 years; mean 43.2 years), presented after a short duration (mean 2.6 months) with a large (mean 5.5 cm) destructive nasal cavity mass, involving multiple contiguous paranasal sites (n = 46) and with cervical adenopathy (n = 41). The tumors showed an alveolar, nested to solid growth pattern below an intact, but often involved (n = 9) epithelium with frequent necrosis (n = 37), destructive bone invasion (n = 30), and lymphovascular invasion (n = 25). The neoplastic cells were dyshesive and dilapidated, with crush artifacts. Rhabdoid features (n = 36) and tumor cell multinucleation (n = 28) were common. Mitotic counts were high (mean 17/10 HPFs). The neoplastic cells showed the following immunohistochemical positive findings: desmin (100%), myogenin (100%), MYOD1 (100%), MSA (96%), SMA (52%), CAM5.2 (50%), AE1/AE3 (36%); other positive markers included S100 protein (27%), CD56 (100%), synaptophysin (35%), and chromogranin (13%). Overall, 54% show epithelial marker reactivity. Molecular studies showed FOXO1 translocations (81%) with PCR demonstrating PAX3 in 72.7% tested. Patients presented with high stage (IV 24; III 26) and metastatic disease (lymph nodes n = 41; distant metastases n = 25) (IRSG grouping). Surgery (n = 16), radiation (n = 41) and chemotherapy (n = 45) yielded an overall survival of 36.1 months (mean; range 2.4-286); 18 alive without disease (mean 69.6 months); 7 alive with disease (mean 11.0 months); 1 dead without disease (63.7 months); and 26 dead with disease (mean 18.5 months). SNT ARMS frequently present in adults as a large, destructive midline mass of short symptom duration, with high stage disease. The alveolar to solid pattern of growth of cells with rhabdoid-plasmacytoid features suggests the diagnosis, but epithelial immunohistochemistry markers are present in 54% of cases, leading to misdiagnosis as carcinomas if muscle markers are not also performed. Overall survival of 36.1 months is achieved with multimodality therapy, but 64% have incurable disease (16.9 months). Mixed anatomic site (p = 0.02) was a significant adverse prognostic indicator, while stage (0.06) and tumor size >5 cm (0.06) approached marginal significance.

SMARCA4-deficient Sinonasal Carcinoma

The term "sinonasal undifferentiated carcinoma (SNUC)" has been coined in 1986 for a highly aggressive sinonasal tract epithelial neoplasm showing distinctive morphology, but lacking any specific line of differentiation. Recent developments resulted in a dynamic splitting of new entities traditionally included in the spectrum of SNUC. Sinonasal NUT-midline carcinoma, adamantinoma-like Ewing family tumors and most recently, SMARCB1(INI1)-deficient sinonasal carcinoma are the main entities defined by specific genetic aberrations. To our knowledge, involvement of subunits of the SWItch/Sucrose Non-fermentable (SWI/SNF) chromatin remodeling complex other than SMARCB1 has not been implicated in the pathogenesis of SNUC-like neoplasms. We herein describe a 40-year-old woman who presented with a large infiltrative mass involving the right nasal cavity and the sinuses with extension into the skull base and periorbital tissue (cT4N2M0). Biopsies were interpreted initially as poorly differentiated neuroendocrine carcinoma followed by surgical resection and radiochemotherapy. No other extra-nasal tumor was detected on imaging. The patient was alive with disease at last follow-up (9 months from initial diagnosis). Histological evaluation showed poorly differentiated small round blue cell neoplasm with diffuse expression of pancytokeratin but not high molecular weight cytokeratin subsets, CK7, p63, S100, desmin or NUT. Neuroendocrine markers showed limited focal weak reactivity. SMARCB1, SMARCA2 and ARID1A were intact in the tumor cells but SMARCA4 was completely lost. This case highlights the rare occurrence of SMARCA4-deficiency in poorly differentiated sinonasal carcinomas and points to the importance of including other SWI/SNF complex subunits in the evaluation of SMARCB1-intact sinonasal malignancies.