Sinonasal Tumors With Neuroepithelial Differentiation (Olfactory Carcinoma): Delineation of Their Pathologic and Clinical Features With Insights into Their Relationship to Olfactory Neuroblastoma and Sinonasal Carcinoma

Neuroendocrine and undifferentiated sinonasal and skull base tumors: An up-to-date narrative review

Tumors located in the nasal cavity, paranasal sinuses and the skull base comprise a wide range of histologic subtypes. Among them, neuroendocrine and undifferentiated tumors are rare but noteworthy, because of their distinctive features, aggressive nature, and diagnostic complexities. A literature search was conducted in the PubMed/MEDLINE and the Scopus databases from 2019 until inception. The keywords "neuroendocrine", "undifferentiated", "nose", "sinonasal", "paranasal", "skull base" were used. Thirty-eight articles referring to neuroendocrine and undifferentiated tumors of the nose, paranasal sinuses and the skull base were finally included and analyzed. Neuroendocrine and undifferentiated tumors of the nose, paranasal sinuses and the skull base are infrequent malignancies, most commonly affecting middle-aged men. They usually present with non-specific symptoms, even though ocular or neurologic manifestations may occur. Prognosis is generally poor; however, novel targeted and immunological therapies have shown promising results. Sinonasal Neuroendocrine Carcinomas (SNECs) carry distinct histological and immunohistochemical features. Management consists of surgical resection coupled with systematic therapy. Sinonasal Undifferentiated Carcinomas (SNUCs) lack specific squamous or glandular features. They typically stain positive for pancytokeratin and INI1 antibody. Treatment includes induction chemotherapy, followed by a combination of chemotherapy and radiotherapy. Olfactory neuroblastomas (ONBs) have neuroepithelial or neuroblastic features. They show diffuse positivity for various markers, including synaptophysin, chromogranin, and neuron-specific enolase (NSE). Surgical resection plus radiotherapy is considered the treatment of choice. In conclusion, neuroendocrine and undifferentiated tumors arising from the nose, paranasal sinuses and the skull base represent a unique group of malignancies. A thorough understanding of their clinical features, molecular changes, diagnostic approaches, treatment modalities, and prognostic factors is critical for providing optimal patient care. Still, continued research efforts and multidisciplinary collaboration are warranted, in order to improve outcomes for patients diagnosed with these rare and aggressive tumors.

Recurrent Wnt Pathway and ARID1A Alterations in Sinonasal Olfactory Carcinoma

Sinonasal tumors with neuroepithelial differentiation, defined by neuroectodermal elements reminiscent of olfactory neuroblastoma (ONB) and epithelial features such as keratin expression or gland formation, are a diagnostically challenging group that has never been formally included in sinonasal tumor classifications. Recently, we documented that most of these neuroepithelial neoplasms have distinctive histologic and immunohistochemical findings and proposed the term "olfactory carcinoma" to describe these tumors. However, the molecular characteristics of olfactory carcinoma have not yet been evaluated. In this study, we performed targeted molecular profiling of 23 sinonasal olfactory carcinomas to further clarify their pathogenesis and classification. All tumors included in this study were composed of high-grade neuroectodermal cells that were positive for pankeratin and at least 1 specific neuroendocrine marker. A significant subset of cases also displayed rosettes and neurofibrillary matrix, intermixed glands with variable cilia, peripheral p63/p40 expression, and S100 protein-positive sustentacular cells. Recurrent oncogenic molecular alterations were identified in 20 tumors, including Wnt pathway alterations affecting CTNNB1 (n = 8) and PPP2R1A (n = 2), ARID1A inactivation (n = 5), RUNX1 mutations (n = 3), and IDH2 hotspot mutations (n = 2). Overall, these findings do demonstrate the presence of recurrent molecular alterations in olfactory carcinoma, although this group of tumors does not appear to be defined by any single mutation. Minimal overlap with alterations previously reported in ONB also adds to histologic and immunohistochemical separation between ONB and olfactory carcinoma. Conversely, these molecular findings enhance the overlap between olfactory carcinoma and sinonasal neuroendocrine carcinomas. A small subset of neuroepithelial tumors might better fit into the superseding molecular category of IDH2-mutant sinonasal carcinoma. At this point, sinonasal neuroendocrine and neuroepithelial tumors may best be regarded as a histologic and molecular spectrum that includes core groups of ONB, olfactory carcinoma, neuroendocrine carcinoma, and IDH2-mutant sinonasal carcinoma.

Update on olfactory neuroblastoma

Olfactory neuroblastomas are uncommon malignancies that arise from olfactory receptor cells located high in the nasal cavity. Accurate diagnosis plays a crucial role in determining clinical results and guiding treatment decisions. Diagnosis can be a major challenge for pathologists, especially when dealing with tumours with poor differentiation. The discovery of several molecular and immunohistochemical markers would help to overcome classification difficulties. Due to the paucity of large-scale studies, standardisation of diagnosis, treatment and prediction of outcome remains a challenge. Surgical resection by endoscopic techniques with the addition of postoperative irradiation is the treatment of choice. In addition, it is advisable to consider elective neck irradiation to minimise the risk of nodal recurrence. Molecular characterisation will help not only to make more accurate diagnoses but also to identify specific molecular targets that can be used to develop personalised treatment options tailored to each patient. The present review aims to summarise the current state of knowledge on histopathological diagnosis, the molecular biology and management of this disease.

Top IHC/ISH Hacks for and Molecular Surrogates of Poorly Differentiated Sinonasal Small Round Cell Tumors

BACKGROUND

Poorly differentiated sinonasal small round cell tumors (SRCTs) are rare and heterogeneous, posing challenges in diagnosis and treatment.

METHODS

Recent advances in molecular findings and diagnostic refinement have promoted better understanding and management of these tumors.

RESULTS

The newly defined and emerging sinonasal entities demonstrate diverse morphologies, specific genomic signatures, and clinical behavior from conventional counterparts. In this review of SRCTs, emphasis is placed on the diagnostic approach with the employment of a pertinent panel of immunohistochemistry studies and/or molecular tests, fine-tuned to the latest WHO 5 classification of sinonasal/paranasal tumors and personalized treatment.

CONCLUSION

Specifically, this review focuses on tumors with epithelial and neuroectodermal derivation.

Diagnostic and Treatment-Related Challenges in Sinonasal Teratocarcinosarcoma: A Report of Three Cases

Background

Sinonasal teratocarcinosarcoma is a rare, aggressive malignancy located almost exclusively in the nasal cavity, paranasal sinuses, or anterior skull base. Histopathological diagnosis can be challenging due to the heterogeneous composition.

Methods

Retrospective analysis of 3 patients with sinonasal teratocarcinosarcoma diagnosed and treated at the University Medical Center Utrecht was conducted.

Results

Patients presented with nasal obstruction, epistaxis, headaches, or behavioral changes. All three patients had locally advanced disease, and one had lymph node metastases. Two patients underwent surgery followed by radiotherapy, and one underwent neoadjuvant chemotherapy followed by surgery. The follow-up duration ranged from 3 to 32 months. All three patients died due to progression of their disease.

Conclusion

Sinonasal teratocarcinosarcoma is characterized by rapid, aggressive local expansion. The prognosis is poor due to a high risk of metastases and locally recurrent disease. Multimodality treatment consisting of surgery, followed by (chemo)-radiotherapy, is essential for optimizing outcomes. Neoadjuvant therapy offers a promising treatment option.

Adamantinoma-like Ewing Sarcoma (ALES) May Harbor FUS Rearrangements : A Potential Diagnostic Pitfall

Adamantinoma-like Ewing sarcoma (ALES) is a rare malignancy currently considered a variant of Ewing sarcoma with most known cases harboring EWSR1 rearrangements. Herein we present a series of 6 cases of EWSR1 -negative ALES. The tumors arose in the sinonasal tract (n=3), major salivary glands (submandibular gland=1; parotid=1), and anterior mediastinum (n=1) in patients ranging from 25 to 79 years of age. Most tumors were basaloid in appearance, growing in large nests separated by interlobular fibrosis without overt squamous pearls. However, 1 case closely resembled a well-differentiated neuroendocrine tumor with uniformly round nuclei, eosinophilic cytoplasm, and trabecular architecture. All cases were diffusely positive for pan-cytokeratin, p40 or p63, and CD99. A subset of cases showed diffuse reactivity for synaptophysin, including 1 sinonasal tumor which also demonstrated sustentacular S100 protein expression. Molecular testing showed FUS rearrangements in all cases. Gene partners included known ETS family members FEV (n=2) and FLI1 (n=1). Our results expand the molecular diagnostic considerations for ALES to include FUS rearrangements. We also show that ALES may harbor FUS :: FLI1 fusion, which has not been previously reported in the Ewing family of tumors. Furthermore, ALES may show unusual histologic and immunophenotypic features that can overlap with olfactory carcinoma including S100-positive sustentacular cells. ALES should be considered in the diagnostic differential of small round cell tumors and tumors with neuroendocrine differentiation with immunohistochemical workup to include p40 and CD99/NKX2.2.

Challenging differential diagnoses in small biopsies from the sinonasal tract

Sinonasal biopsy specimens are a challenging area in anatomic pathology. The small, often fragmented or crushed nature of these biopsies can hinder morphologic assessment. Additionally, many of the tumors in this area are rare and share morphologic, and sometime immunophenotypic similarities. In many cases, immunohistochemistry is helpful if not necessary to reach a specific diagnosis. In other cases, a specific diagnosis is not possible and a differential diagnosis must be given on a biopsy specimen despite access to a well-equipped immunohistochemistry laboratory. This review article groups some of the more challenging entities in the sinonasal region based on morphologic patterns. These include low grade squamoid lesions such as sinonasal (Schneiderian) papilloma and DEK::AFF2 rearranged carcinoma, glandular neoplasms such as intestinal and non-intestinal type sinonasal adenocarcinoma, high-grade carcinomas such as HPV-related multiphenotypic sinonasal carcinoma, NUT carcinoma and SWI/SNF deficient carcinomas, small round blue cell tumors such as teratocarcinosarcoma, neuroendocrine carcinoma and olfactory neuroblastoma, and finally, low grade spindle cell neoplasms such as glomangiopericytoma, biphenotypic sinonasal sarcoma and solitary fibrous tumor.

Proceedings of the 2023 North American Society of Head and Neck Pathology Companion Meeting, New Orleans, LA, March 12, 2023: Navigating New Developments in High Grade Sinonasal Neuroendocrine and Neuroectodermal Neoplasms

Although the definitions of sinonasal neuroendocrine and neuroectodermal neoplasms did not change substantially in the 5th edition WHO Classification of Head and Neck Tumours, the diagnosis of olfactory neuroblastoma (ONB), small cell neuroendocrine carcinoma, and large cell neuroendocrine carcinoma remains quite challenging in practice. Ambiguities surrounding the amount of keratin expression allowable in ONB and the amount of neuroendocrine differentiation seen in sinonasal undifferentiated carcinoma (SNUC) lead to significant diagnostic discrepancies at the high grade end of this tumor spectrum. Furthermore, a group of problematic neuroepithelial tumors that show overlapping features of ONB and neuroendocrine carcinoma have never been recognized in formal classification schemes. Since publication of the 5th edition WHO, two new tumor entities have been proposed that help resolve these problems. Olfactory carcinoma is defined by high grade keratin-positive neuroectodermal cells with frequent intermixed glands and shows recurrent Wnt pathway, ARID1A, and RUNX1 alterations. IDH2-mutant sinonasal carcinoma is a molecularly-defined category that encompasses tumors with undifferentiated (SNUC), large cell neuroendocrine, and neuroepithelial phenotypes. This review will provide a practical overview of these emerging entities and their application to diagnostic challenges in the post-WHO sinonasal neuroendocrine and neuroectodermal tumor classification.

Sinonasal Cancer: Improving Classification, Stratification and Therapeutic Options

The nasal cavities and paranasal sinuses are the site of origin of a wide spectrum of histologically and clinically distinct disease entities [...]

Top 10 Nested Pattern Head and Neck Lesions to Notice

BACKGROUND

Nested is defined as "cellular clusters arranged in small groupings with intervening vascular or stromal networks, lacking lumens or glandular formation." Using this definition, multiple neoplastic and non-neoplastic lesions of the head and neck come into the differential. We have broadly organized the differential diagnosis of "nested" tumors into entities with neuroendocrine differentiation, squamous differentiation, thyroid follicular cell differentiation, and other lesions.

METHODS

Review.

RESULTS

Many different entities have a nested appearance and the morphologic, immunohistochemical, clinical, and radiographic features contribute to the differential diagnosis. The different tumors covered in this review include neuroendocrine neoplasms, paraganglioma, middle ear neuroendocrine tumor (formerly known as middle ear adenoma), medullary thyroid carcinoma, poorly differentiated thyroid carcinoma, olfactory neuroblastoma, ectopic pituitary neuroendocrine tumor, hyalinizing trabecular tumor, solid subtype of papillary thyroid carcinoma, solid cell nests/C-cell hyperplasia, necrotizing sialometaplasia, and meningioma.

CONCLUSION

In this review, we discuss the morphologic and immunohistochemical features of the covered entities as a guide to differential diagnosis when nested-patterned head and neck lesions are encountered.

SWI/SNF-deficient Sinonasal Carcinomas

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

Targeted next-generation sequencing reveals activating CTNNB1 mutations in SMARCA4/BRG1-deficient sinonasal carcinomas: a report of two new cases and a brief review of the literature with an emphasis on histogenesis

SMARCA4/BRG1 is a catalytic subunit of the SWItch/sucrose non-fermentable (SWI/SNF) complex and its inactivation is known to drive a variety of cancers across different organs. SMARCA4/BRG1-deficient carcinoma is a relatively new entity in the sinonasal region, and a comprehensive molecular investigation of the underlying genetic abnormalities is largely lacking. In this study, we report two new cases of SMARCA4/BRG1-deficient sinonasal carcinoma with targeted next-generation sequencing analysis, both of which revealed activating mutation of CTNNB1 in addition to somatic loss-of-function mutation of SMARCA4, providing further insights into its tumorigenesis and theoretical basis for the potential future targeted therapy. Activating CTNNB1 mutations in our cases may provide further evidence that SMARCA4-deficient sinonasal carcinoma, sinonasal teratocarcinosarcoma, and olfactory carcinoma are genetically closely related lesions, as recently proposed in the literature.

Olfactory Neuroblastoma: Morphological Reappraisal and Molecular Insights with Quantum Leap in Clinical Perspectives

PURPOSE OF REVIEW

The purpose of review is to provide a comprehensive review of the literature focusing on the recent advances in the diagnosis, molecular underpinning, and targeted therapy of olfactory neuroblastoma (ONB).

RECENT FINDINGS

Studies focused on the molecular fingerprinting of ONB are critical to engage new promising treatment strategies. Molecular-based subtype classifications have been proposed (basal-like ONB and neural-like ONB) but are not widely used. The rationale for implementation of DNA methylation analysis and IDH2 sequencing in routine work-up for ONB is gaining recognition. Expression of somatostatin receptors (SSTR) in ONB open new avenues for both, diagnostic (especially metastatic disease) and new treatment protocols with somatostatin analogs. Olfactory carcinoma is proposed as a unifying diagnostic terminology pertinent to epithelial divergent differentiation in olfactory neuroblastoma. Molecular (genetic and epigenetic) efforts on olfactory neuroblastoma are promising; however further refinement is needed for employment of these biomarkers as clinical standard of care. Ongoing and future multi-institutional collaborative studies will contribute to further understanding of ONB biology and aid the development of targeted treatments for this disease.