Nasal chondromesenchymal hamartoma (NCMH): a rare DICER1-associated tumour in an adult male.

An adult male presented to the ENT clinic with a 1-year history of unilateral nasal blockage. He had presented to another institution 5 years previously with the same issue, undergoing resection of what was reported to be a benign inflammatory polyp with osseous metaplasia. Detailed examination revealed a large mass filling the left nasal cavity. Excisional biopsy and secondary specialist review of pathology revealed nasal chondromesenchymal hamartoma (NCMH) with associated DICER1 mutations. NCMH is a rare, benign tumour of the sinonasal tract, presenting more often in the early childhood, with symptoms related to the site and extent of the tumour. As highlighted in this case, complete excision is mandatory for definitive diagnosis and treatment of NCMH, and an awareness of the association with DICER1 mutation, which can predispose individuals to a range of neoplasia, is key to providing appropriate genetic counselling.

Thyroglossal duct cyst carcinoma case series-Management strategy and outcomes / Serie de casos de carcinoma del conducto tirogloso: estrategias de tratamiento y resultados

Objective: To review the clinical presentation, diagnosis, pathology and management strategies in a modern cohort of patients with thyroglossal duct cyst carcinoma. Study design: Retrospective case series following PROCESS Guidelines. Setting Comprehensive cancer centre. Methods: Data recorded included: gender, age at diagnosis, clinical presentation, thyroid function, diagnostic investigations, cytological results, final histology, staging and follow up status. The risk of malignancy in cytological analysis was stratified according to the Royal College of Pathologists classification in United Kingdom. Results: Twelve patients were included. The majority of patients (66.7%) presented with an isolated thyroglossal duct cyst. Only 4 patients had preoperative cytological suspicion of carcinoma (sensitivity: 33.3%). At the time of presentation all patients were euthyroid. Following diagnosis of malignancy, a total thyroidectomy was performed in all patients, with the exception of 2, who had a thyroglossal duct cyst carcinoma of less than 10mm. Among the 10 patients who underwent total thyroidectomy, 7 (70%) patients had proven carcinoma in the thyroid gland, 3 with deposits of less than 10mm. The average size of the thyroid cancer deposits was 7.2mm (1–20mm). With a mean follow-up of is 44 months (5–120), all patients were alive and free of recurrence at the end of the study period. Conclusion: Thyroglossal duct cyst carcinoma is a rare condition and its management should be discussed in a multidisciplinary meeting. As with differentiated thyroid cancer originating in the thyroid gland, it bears extraordinary survival rates. Accordingly, the management of these cancers has shifted towards a more conservative approach although its peculiarities must be taken into account: ease of extracystic invasion and possible different lymph node invasion. (AU)

Objetivo: Revisar la presentación clínica, el diagnostico, la histología y las estrategias de tratamiento en una cohorte moderna de pacientes con carcinoma del conducto tirogloso. Diseño del estudio: Serie de casos retrospectiva utilizando PROCESS Guidelines. Localización: Unidad de cáncer de cabeza y cuello. Métodos: Los datos incluidos fueron: sexo, edad al diagnóstico, presentación clínica, función tiroidea, investigaciones diagnósticas, resultados citológicos, histología final, estadificación y estado durante el seguimiento. El riesgo de malignidad en el análisis citológico fue estratificado de acuerdo con la clasificación del Royal College of Pathologists del Reino Unido. Resultados: Se incluyeron 12 pacientes. La mayoría de ellos (66,7%) presentaron solamente un quiste del conducto tirogloso al diagnóstico. Solamente 4 pacientes tuvieron sospecha de malignidad de acuerdo con los resultados de la citología preoperatoria. En el momento de la presentación, todos los pacientes tenían función tiroidea normal. Después del diagnóstico, se realizó tiroidectomía total a todos los pacientes menos dos, que tuvieron carcinoma del conducto tirogloso menor de 10mm. Entre los 10 pacientes que recibieron tiroidectomía total, 7 (70%) sufrieron carcinoma en la glándula tiroides, 3 de ellos con depósitos menores de 10mm. El tamaño medio de los depósitos de carcinoma en la glándula tiroides fue de 7,2mm (1-20mm). Con una media de seguimiento de 44meses (5-120), todos los pacientes estaban vivos y libres de recidiva al final del periodo estudiado. Conclusión: El carcinoma del conducto tirogloso es una entidad poco frecuente y su manejo debe ser realizado por un equipo multidisciplinario. Igual que en el carcinoma diferenciado de tiroides que se origina en la glándula tiroides, las tasas de supervivencia son excelentes. ... (AU)

Thyroglossal duct cyst carcinoma case series-Management strategy and outcomes.

OBJECTIVE: To review the clinical presentation, diagnosis, pathology and management strategies in a modern cohort of patients with thyroglossal duct cyst carcinoma. STUDY DESIGN: Retrospective case series following PROCESS Guidelines. SETTING: Comprehensive cancer centre. METHODS: Data recorded included: gender, age at diagnosis, clinical presentation, thyroid function, diagnostic investigations, cytological results, final histology, staging and follow up status. The risk of malignancy in cytological analysis was stratified according to the Royal College of Pathologists classification in United Kingdom. RESULTS: Twelve patients were included. The majority of patients (66.7%) presented with an isolated thyroglossal duct cyst. Only 4 patients had preoperative cytological suspicion of carcinoma (sensitivity: 33.3%). At the time of presentation all patients were euthyroid. Following diagnosis of malignancy, a total thyroidectomy was performed in all patients, with the exception of 2, who had a thyroglossal duct cyst carcinoma of less than 10mm. Among the 10 patients who underwent total thyroidectomy, 7 (70%) patients had proven carcinoma in the thyroid gland, 3 with deposits of less than 10mm. The average size of the thyroid cancer deposits was 7.2mm (1-20mm). With a mean follow-up of is 44 months (5-120), all patients were alive and free of recurrence at the end of the study period. CONCLUSION: Thyroglossal duct cyst carcinoma is a rare condition and its management should be discussed in a multidisciplinary meeting. As with differentiated thyroid cancer originating in the thyroid gland, it bears extraordinary survival rates. Accordingly, the management of these cancers has shifted towards a more conservative approach although its peculiarities must be taken into account: ease of extracystic invasion and possible different lymph node invasion.

DEK::AFF2 Fusion Carcinomas of Head and Neck.

A novel DEK::AFF2 fusion carcinoma was recently described in 29 patients who originally presented with non-viral-associated nonkeratinizing squamous cell carcinoma. The tumors occurred at multiple sites in the head and neck including in the sinonasal tract, middle ear, and temporal bone. This tumor behaves aggressively involving adjacent vital structures, frequently recurs, and is inclined to develop lymph node and distant metastasis. This review aims to summarize the demographic, clinical, pathologic, immunophenotypic features, and pattern of molecular alterations as well as to discuss the differential diagnosis of DEK::AFF2 fusion carcinoma.

Salivary carcinosarcoma: insight into multistep pathogenesis indicates uniform origin as sarcomatoid variant of carcinoma ex pleomorphic adenoma with frequent heterologous elements.

AIMS: The formal pathogenesis of salivary carcinosarcoma (SCS) remained unclear, both with respect to the hypothetical development from either preexisting pleomorphic adenoma (PA) or de novo and the clonal relationship between highly heterogeneous carcinomatous and sarcomatous components. METHODS AND RESULTS: We performed clinicopathological and molecular (targeted RNA sequencing) analyses on a large series of 16 cases and combined this with a comprehensive literature search (111 cases). Extensive sampling (average 11.6 blocks), combined with immunohistochemistry and molecular studies (PA-specific translocations including PLAG1 or HMGA2 proven in 6/16 cases), enabled the morphogenetic identification of PA in 15/16 cases (93.8%), by far surpassing a reported rate of 49.6%. Furthermore, we demonstrated a multistep (intraductal/intracapsular/extracapsular) adenoma-carcinoma-sarcoma-progression, based on two alternative histogenetic pathways (intraductal, 56.3%, versus myoepithelial pathway, 37.5%). Thereby, early intracapsular stages are identical to conventional carcinoma ex PA, while later extracapsular stages are dominated by secondary, frequently heterologous sarcomatous transformation with often large tumour size (>60 mm). CONCLUSION: Our findings strongly indicate that SCS (almost) always develops from PA, with a complex multistep adenoma-carcinoma-sarcoma-sequence, based on two alternative histogenetic pathways. The findings from this novel approach strongly suggest that SCS pathogenetically is a rare (3-6%), unique, and aggressive variant of carcinoma ex PA with secondary sarcomatous overgrowth. In analogy to changes of terminology in other organs, the term "sarcomatoid carcinoma ex PA with/without heterologous elements" might be more appropriate.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumours: Tumours of the Ear.

In the recently published 5th Edition of the World Health Organisation Classification of Head and Neck Tumours, there are relatively few changes to report in terms of nomenclature in lesions of ear and temporal bone and fewer developments in molecular pathogenesis in comparison to other sites, particularly in sinonasal tract. Ear and temporal bone tumours are rare and biopsy material is limited. As a result, resources in the literature are scarce with few large series, no controlled clinical trials and the approaches to staging and management are not standardised. New entities are difficult to characterise. The number of entries has, however, increased for tumours of the ear and temporal bone (thirteen) compared to the 4th Edition (eleven). Some lesions previously included in the 4th Edition considered to have no site-specific features have been excluded to be discussed elsewhere and other benign lesions that are specific to this site have been included. The tumours and tumour-like entities of ear and temporal bone are discussed here mindful that the chapter in the 5th edition better correlates disease processes with clinical information and imaging and as far as possible standardises nomenclature.

Serial step sections at narrow intervals with immunohistochemistry are required for accurate histological assessment of sentinel lymph node biopsy in oral squamous cell carcinoma.

BACKGROUND: Sentinel lymph node (SLN) biopsy is an accurate staging modality in early oral squamous cell carcinoma (OSCC), but its accuracy relies on labor-intensive histopathology protocols. We sought to determine whether serial step sections with immunohistochemistry (SSSIHC) at narrow intervals of the entire SLN are required to accurately exclude metastasis. METHODS: Consecutive SLN biopsies over a 13-year period were retrospectively evaluated. If the index section was negative for carcinoma, the entire SLN was subjected to SSSIHC at 150 µm intervals. The first section level and total number of section levels to contain carcinoma were recorded. RESULTS: One hundred and eighteen SLN+ from 90 patients were included. SSSIHC upstaged the nodal status in 19.5% of patients. Metastasis was identified in 16.7% and 10.2% beyond section levels 4 and 6, respectively. Among SLNs requiring SSSIHC, 47.5% contained carcinoma in a single section level. CONCLUSION: SSSIHC of the entire SLN at 150 µm intervals are required to identify occult metastasis in OSCC.

Case report of a man with multiple paragangliomas and pathogenic germline variants in both NF1 and SDHD.

We report a novel case of multiple paragangliomas in a patient who was identified with pathogenic variants in both NF1 and SDHD genes. The proband is a man with known familial NF1 disease, diagnosed clinically in childhood. Multiple head and neck paragangliomas (HNPGL) were found during investigations for acute left sided neurological symptoms, in the region of his known plexiform neurofibroma. He was referred for genetic counselling. He underwent surgery to remove a left carotid body tumor (CBT). A pheochromocytoma and paraganglioma gene panel was tested. Blood and HNPGL tumor DNA were analyzed by whole exome sequencing. In addition to the NF1 truncating variant c.5107delA, p.(Ser1703AlafsTer7), the SDHD truncating pathogenic variant c.3G > A, p.(Met1?) was found. Tumor sequencing showed no LOH of SDHD or NF1, but monoallelic loss of 11p15 and 11q12.2-q12.3 was observed. Co-occurrence of pathogenic variants in multiple cancer susceptibility genes is rare but possible, identified by the increased use of panel testing. This is the first description of a patient presenting with NF1 and SDHD dual pathology, with HNPGL development due to SDHD. This case illustrates the central role of genetic sequencing in PPGLs and the strong genotype-phenotype correlations of different genes.

Why is the histomorphological diagnosis of tumours of minor salivary glands much more difficult?

AIMS: There is a widespread perception among clinicians and pathologists that the histomorphological assessment of minor salivary gland (MinSG) tumours is more difficult and hampered by more misdiagnoses than that of major salivary gland tumours. This is based on a vague, subjective clinical impression, lacking scientific proof. The aim of the present study was to identify and statistically verify potential reasons that could explain this difference. METHODS AND RESULTS: We identified 14 putative clinical, pathological and combined clinicopathological reasons that, altogether, could explain the phenomenon of the perceived greater diagnostic difficulty associated with MinSG tumours. We performed a comprehensive literature search and a statistical comparison of data from a large personal consultation series (biased for difficult cases) with cumulated data from straightforward, unselected (non-consultation) series from the literature. By performing this comparison, we identified, with statistical significance, a comprehensive series of reasons, as well as of consequences, of the greater difficulty in diagnosing MinSG tumours. CONCLUSIONS: Among the 14 criteria, high frequencies of initial incisional biopsies and of a low-grade category in malignant tumours emerged as the two most important reasons for enhanced diagnostic difficulty. Very rare entities, unusual locations, shortcomings in clinicopathological communication, and pecularities of the special anatomical location of the hard palate, such as tumour necrosis, mucosal ulceration, pseudoinvasion, and the peculiar phenomenon of 'tumoral-mucosal fusion', contribute to further diagnostic difficulties. The awareness of these shortcomings and pitfalls enables us to provide a series of recommendations for clinicians and pathologists that might aid in assessment and reduce the rate of misdiagnosis of MinSG tumours.

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.

TNM 8 staging is a better prognosticator than TNM 7 for patients with locally advanced oral cavity squamous cell carcinoma treated with surgery and post-operative radiotherapy.

PURPOSE: To assess TNM 8 staging in discriminating overall survival (OS) amongst patients with locally advanced oral cavity squamous cell carcinoma (OCSCC) treated with surgery and post-operative radiotherapy (PORT), compared to TNM 7. MATERIAL AND METHODS: Data from OCSCC patients treated with surgery and PORT between January 2010 and December 2018 were reviewed. Demographics, tumour characteristics and treatment response data were collected, and patients staged according to both TNM 7 and TNM 8. OS and disease free survival (DFS) were estimated using the Kaplan Meier method. Univariate and multivariable analyses were conducted for factors affecting OS, DFS and early disease recurrence within 12 months. RESULTS: Overall 172 patients were analyzed. Median follow up was 32 months for all patients and 48 months for surviving patients. TNM 8 staging demonstrated significant stratification of OS and DFS amongst the entire cohort, whereas TNM 7 staging did not. On multivariable analysis, TNM 8 stage, performance status (PS) and a positive surgical margin were prognostic for OS. Looking at disease recurrence within 12 months, TNM 8 stage IVB, presence of lymphovascular invasion (LVSI), younger age and lesser smoking history were predictive factors on multivariable analysis. CONCLUSION: TNM 8 is a good development of its predecessor in terms of predicting survival for patients with locally advanced OCSCC. We have also identified younger age (<60 years) and a smoking history of <10 pack years as risk factors for early disease recurrence, potentially representing a separate biological cohort within OCSCC patients.

Olfactory neurocytoma as a unique cause of chronic SIADH.

A 32-year-old man was found to have a nasal mass on DOTATATE positron emission tomography (PET) scan to investigate the cause of his syndrome of inappropriate antidiuretic hormone secretion (SIADH). The patient presented 6 years earlier with malignant hypertension followed by a second emergency admission for hyponatraemia. Multiple scans and blood tests over 6 years yielded no cause for his SIADH. Nasendoscopy was unremarkable. A PET scan prompted endoscopic sinus surgery which resulted in the resection of a mass in the anterior hiatus semilunaris. The histological findings were fitting with a diagnosis of a neurocytic-type tumour favouring an olfactory neurocytoma. Following resection, the patient remains well and is cured of his SIADH. An olfactory neurocytoma although rare should be considered as a benign differential for a mass in the nasal space. This case demonstrates how an olfactory neurocytoma can present as a cause of SIADH.

Metal-Working Fluids Exposure and a Rare Frontoethmoid Lesion.

This case report describes a unique nasal mass that was difficult to diagnose clinically and histologically. The patient was a middle-aged man employed as a metalworker, and he presented with a unilateral nasal obstruction and a mass arising from the right middle meatus. After a series of investigations, he underwent right-sided sphenoethmoidectomy with excision of a nasal lesion. The surgical specimen presented a major diagnostic challenge for the pathologists and clinicians involved. A series of discussions amongst two different head and neck expert teams combined with detailed clinicopathological correlation resulted in a diagnosis of a granulomatous lesion or pseudotumour related to the ingestion of water-soluble cutting oils, or "Suds oil," as they are more commonly called. Although occupational exposures to certain inhalants, such as wood dust and formaldehyde, are well-known risk factors for sinonasal lesions, here we present a rare association between a sinonasal lesion and another inhalant, Suds oil, that has not been previously reported in the literature.

Clinical evaluation of tumour-infiltrating lymphocytes as a prognostic factor in patients with human papillomavirus-associated oropharyngeal squamous cell carcinoma.

Clinical evaluation of tumour-infiltrating lymphocytes as a prognostic factor in patients with human papillomavirus-associated oropharyngeal squamous cell carcinoma AIMS: The majority of patients with human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OpSCC) have favourable survival outcomes, but a significant minority of individuals will die of their disease. There are currently no definitive criteria with which to identify HPV-associated OpSCC patients with poor outcomes. Recent reports suggest that quantitative evaluation of T-cell subpopulations in OpSCC may be of prognostic value, but the methods used have limited utility in a clinical diagnostic setting. We therefore sought to determine the clinical prognostic utility of tumour-infiltrating lymphocyte (TIL) evaluation in patients with HPV-associated OpSCC within the context of a diagnostic histopathology setting. METHODS AND RESULTS: Representative diagnostic haematoxylin and eosin (H&E)-stained slides from 232 consecutive HPV-associated OpSCC patients were classified as containing a high (TILHi ; diffuse, lymphocytes in >80% of tumour and stroma), moderate (TILMod ; patchy, present in 20-80% of tumour and stroma) or low (TILLo ; sparse or absent, present in <20% of tumour and stroma) TILs. Interobserver reliability was assessed, and TIL category was then correlated with overall survival (OS) and disease-free survival (DFS). Univariate and multivariate analyses showed statistically significant differences in OS and DFS estimates when TILHi and TILMod patients were compared with TILLo patients (P < 0.0001 for TILHi versus TILLo ; P < 0.0001 for TILMod versus TILLo ). Statistical significance was retained when TILHi and TILMod patients were grouped into a single category (TILHi ) and compared with TILLo patients (P < 0.0001). CONCLUSION: We demonstrate the prognostic utility of TILs in patients with HPV-associated OpSCC in clinical practice. A binary system classifying HPV-associated OpSCC into TILHi and TILLo on the basis of routine H&E staining stratifies patients into those with potentially favourable and unfavourable survival outcomes, respectively.

Data Set for the Reporting of Ear and Temporal Bone Tumors: Explanations and Recommendations of the Guidelines From the International Collaboration on Cancer Reporting.

The International Collaboration on Cancer Reporting (ICCR) was established to internationally unify and standardize the pathologic reporting of cancers based on collected evidence, as well as to allow systematic multi-institutional intercountry data collection to guide cancer care in the future. Such collaborative efforts are particularly essential for developing an evidence base for rare neoplasms or those with marked geographic variation in incidence, such as the tumors of the ear and the temporal bone. The ear and the temporal bone, including the external auditory canal and the middle and inner ear, with the closely associated facial nerve, internal carotid artery, and internal jugular vein, is one of the most complex anatomic structures in the head and neck. A wide range of benign and malignant neoplasms arise in this region. The management of these neoplasms involves complex surgery because of the anatomic confines, and as such, both benign and malignant tumors are included in this data set, as the oncologically equivalent management requires a multidisciplinary approach and standardized nomenclature and terminology. Surgical procedures at this site result in multifaceted 3-dimensional specimens that can be difficult to handle at macroscopic exam. A comprehensive macroscopic examination is important for identifying critical prognostic factors and often requires clinical and radiologic correlation. Histologic examination is straightforward for basal cell or squamous cell carcinoma but can be quite challenging for other neoplasms. A summary of the ICCR guidelines for ear tumors is presented, along with discussion of the salient evidence and practical issues.

The surgical management of recurrent tracheal schwannoma.

A case of a primary tracheal schwannoma refractory to endoscopic treatment in a 54-year-old male is reported. Previous treatment was by endoscopic laser debulking. Computed tomography (CT) 2 months later demonstrated a recurrent tumour involving the anterior tracheal wall with intraluminal tracheal extension. Treatment was successful by limited tracheal resection with primary anastomosis performed 2 weeks following the scan. The histology confirmed a benign neurogenic tumour derived from Schwann cells and clear margins.

HPV-related Multiphenotypic Sinonasal Carcinoma: An Expanded Series of 49 Cases of the Tumor Formerly Known as HPV-related Carcinoma With Adenoid Cystic Carcinoma-like Features.

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC), originally known as HPV-related carcinoma with adenoid cystic carcinoma-like features, is a peculiar neoplasm that is restricted to the sinonasal tract, exhibits features of both a surface-derived and salivary gland carcinoma (particularly adenoid cystic carcinoma), and is associated with high-risk HPV. Given the limited number of published cases, the full clinicopathologic spectrum of this neoplasm is unclear. Here, we present an updated experience of 49 cases. All cases of HMSC were obtained from the authors' files. Immunohistochemistry for p16, c-kit, and myoepithelial cell markers (S100, actin, calponin, p63, and/or p40) was performed along with RNA in situ hybridization for HPV (type 33-specific as well as a high-risk cocktail). Fluorescence in situ hybridization studies for fusions of MYB, NFIB, and MYBL1 was performed on a subset of cases. Clinical follow-up was obtained from medical records. A total of 49 cases of HMSC were collected. Twenty-eight (57%) were from women and 18 (43%) from men, ranging in age from 28 to 90 years (mean, 54 y). Of 40 cases with detailed staging information, 43% of HMSCs presented with a high T-stage (T3 or T4). Histologically, most grew predominantly as solid nests of basaloid cells exhibiting high mitotic rates and frequent necrosis, with histologic and immunohistochemical evidence of myoepithelial differentiation. Most cases also demonstrated foci of cribriform and/or tubular growth, along with an inconspicuous population of ducts. Thirty-four (69%) cases demonstrated an unusual pattern of surface involvement where markedly atypical squamous cells colonized tracts of the sinonasal mucosa. Less consistent histologic features included squamous differentiation within the invasive tumor (n=6), sarcomatoid transformation (n=5) including overt chondroid differentiation (n=3), and prominent epithelial-myoepithelial carcinoma-like growth (n=3). All cases were positive for p16 by immunostaining and HPV by RNA in situ hybridization. Thirty-three (67%) were positive for HPV 33. No cases tested for MYB, MYBL1, or NFIB gene fusions were positive. In the 38 cases with follow-up data, (mean follow-up, 42 mo) 14 recurred locally and 2 metastasized (lung, finger). There were no regional lymph node metastases, and no tumor-related deaths. HMSC is a distinct sinonasal neoplasm characterized by myoepithelial differentiation, frequent surface epithelial involvement, and the presence of high-risk HPV (especially type 33). Although it classically exhibits a cribriforming pattern that closely resembles adenoid cystic carcinoma, our expanded series highlights a histologic spectrum that is much broader than previously recognized, warranting a change in terminology. HMSC usually presents as a large and destructive sinonasal mass with high-grade histologic features, but it paradoxically behaves in a relatively indolent manner, underscoring the importance of distinguishing HMSC from true adenoid cystic carcinoma, squamous cell carcinoma, and other histologic mimickers.

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.