SSTR2 Expression in Olfactory Neuroblastoma: Clinical and Therapeutic Implications

Development of an evaluation and treatment strategy for olfactory neuroblastoma: a review of evidence from large-scale studies, including population-based and multicenter studies, and meta-analyses

Olfactory neuroblastoma is a rare sinonasal malignancy arising from the olfactory epithelium that is characterized by skull base involvement and a modest natural history. Because of its rarity and long course, identification of independent prognostic factors is dependent on multivariate analysis of large, long-term data. In this review, we outline evidence for the evaluation and treatment of olfactory neuroblastoma obtained from recent large-scale population-based studies, meta-analyses and multicenter studies. Hyams grade is currently the only pathological grade system for olfactory neuroblastoma. The modified Kadish staging and Dulguerov classification are available for clinical staging. The results of large-scale studies have confirmed Hyams, the modified Kadish and Dulguerov as independent prognostic factors. Surgery followed by radiotherapy provides the best overall survival and recurrence-free survival for resectable disease. The question of whether postoperative radiotherapy should be administered for all cases or only for those at risk of recurrence remains unanswered. Exclusively endoscopic resection is indicated for modified Kadish A/B cases without any increase in the risk of death or recurrence, and is also indicated for modified Kadish C cases if a negative surgical margin is ensured. For more advanced cases, such as those with extensive brain infiltration, the open approach is indicated. Elective nodal irradiation prevents late nodal recurrence of N0 patients. Chemotherapy has failed to show a benefit in survival or disease control. Current needs for olfactory neuroblastoma include the development and validation of refined staging systems suitable for current practice; expansion of indications for endoscopic surgery; less invasive surgery; definitive radiotherapy and novel systemic therapy.

Personalized Approach to Olfactory Neuroblastoma Care

Olfactory neuroblastoma (ONB) is an uncommon neuroendocrine malignancy arising from the olfactory neuroepithelium. ONB frequently presents with nonspecific sinonasal complaints, including nasal obstruction and epistaxis, and diagnosis can be obtained through a combination of physical examination, nasal endoscopy, and computed tomography and magnetic resonance imaging. Endoscopic resection with negative margins, with or without craniotomy, as necessary, is the standard of care for definitive treatment of ONB. Regional metastasis to the neck is often detected at presentation or may occur in a delayed fashion and should be addressed through elective neck dissection or radiation. Adjuvant radiotherapy should be considered, particularly in the case of high grade or tumor stage, as well as positive surgical margins. Systemic therapy is an area of active investigation in both the neoadjuvant and adjuvant setting, with many advocating in favor of induction chemotherapy for significant orbital or intracranial involvement prior to surgical resection. Various targeted immunotherapies are currently being studied for the treatment of recurrent or metastatic ONB. Prolonged locoregional and distant surveillance are indicated following definitive treatment, given the tendency for delayed recurrence and metastasis.

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.

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.

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.

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.

PET/CT Imaging in Treatment Planning and Surveillance of Sinonasal Neoplasms

Sinonasal cancers are uncommon malignancies with a generally unfavorable prognosis, often presenting at an advanced stage. Their high rate of recurrence supports close imaging surveillance and the utilization of functional imaging techniques. Whole-body 18F-FDG PET/CT has very high sensitivity for the diagnosis of sinonasal malignancies and can also be used as a "metabolic biopsy" in the characterization of some of the more common subgroups of these tumors, though due to overlap in uptake, histological confirmation is still needed. For certain tumor types, radiotracers, such as 11C-choline, and radiolabeled somatostatin analogs, including 68Ga-DOTATATE/DOTATOC, have proven useful in treatment planning and surveillance. Although serial scans for posttreatment surveillance allow the detection of subclinical lesions, the optimal schedule and efficacy in terms of survival are yet to be determined. Pitfalls of 18F-FDG, such as post-surgical and post-radiotherapy crusting and inflammation, may cause false-positive hypermetabolism in the absence of relapse.

Top 10 Basaloid Neoplasms of the Sinonasal Tract

BACKGROUND

Basaloid neoplasms of the sinonasal tract represent a significant group of tumors with histological overlap but often with different etiologies (i.e., viral, genetics), clinical management, and prognostic significance.

METHODS

Review.

RESULTS

"Basaloid" generally refers to cells with coarse chromatin in round nuclei and sparse cytoplasm, resembling cells of epithelial basal layers or imparting an "immature" appearance. Tumors with this characteristic in the sinonasal tract are represented by a spectrum of benign to high-grade malignant neoplasms, such as adenoid cystic carcinoma, NUT carcinoma, sinonasal undifferentiated carcinoma, SWI/SNF complex-deficient carcinomas, and adamantinoma-like Ewing sarcoma.

CONCLUSION

In some instances, histology alone may be sufficient for diagnosis. However, limited biopsy material or fine-needle aspiration specimens may be particularly challenging. Therefore, often other diagnostic procedures, including a combination of histology, immunohistochemistry (IHC), DNA and RNA testing, and molecular genetics are necessary to establish an accurate diagnosis.

Updates in management strategies of locally advanced sinonasal malignancy

PURPOSE OF REVIEW

Sinonasal tumors are a rare heterogenous group of pathologies with poor prognosis. In recent years better definition and understanding of histology, molecular classification, biological behavior and advances in therapy have resulted in improved prognosis. The purpose of this review is to give an updated summary of the recent advances in treatment, and where relevant, with references to pathology classifications.

RECENT FINDINGS

Recent publications highlight the role of induction chemotherapy and advances in radiotherapy in advanced cancers. In addition, better understanding of genomics and histology specific treatment algorithms has led to more tailored treatment approaches. The role of immunotherapy and targeted therapy are yet to be explored.

SUMMARY

This review gives an up to date summary of the advances in contemporary management strategies for locally advanced sinonasal malignancies and can serve as a guide for researchers and clinicians.

Tumors of the Nose and Paranasal Sinuses: Promoting Factors and Molecular Mechanisms-A Systematic Review

Sinonasal neoplasms are uncommon diseases, characterized by heterogeneous biological behavior, which frequently results in challenges in differential diagnosis and treatment choice. The aim of this review was to examine the pathogenesis and molecular mechanisms underlying the regulation of tumor initiation and growth, in order to better define diagnostic and therapeutic strategies as well as the prognostic impact of these rare neoplasms. A systematic review according to Preferred Reporting Items for Systematic Review and Meta-Analysis criteria was conducted between September and November 2022. The authors considered the three main histological patterns of sinonasal tumors, namely Squamous Cell Carcinoma, Intestinal-Type Adenocarcinoma, and Olfactory Neuroblastoma. In total, 246 articles were eventually included in the analysis. The genetic and epigenetic changes underlying the oncogenic process were discussed, through a qualitative synthesis of the included studies. The identification of a comprehensive model of carcinogenesis for each sinonasal cancer subtype is needed, in order to pave the way toward tailored treatment approaches and improve survival for this rare and challenging group of cancers.

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.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Nasal Cavity, Paranasal Sinuses and Skull Base

The World Health Organization Classification of Head and Neck Tumours recently published the 5th edition. There are new entities, emerging entities, and significant updates to the taxonomy and characterization of tumor and tumor-like lesions, specifically in this article as it relates to nasal cavity, paranasal sinuses and skull base. Importantly, the number of diagnostic entries has been reduced by creating category-specific chapters for soft tissue, hematolymphoid, melanocytic, neuroectodermal, and metastatic tumors. Bone and salivary gland tumors are also not separately reported in the sinonasal tract, but included in the jaw and salivary gland sections, respectively. Repetition of characteristic entities in each anatomic site was also reduced, instead highlighting only the unique features in each anatomic site. Two new entities (SWI/SNF complex-deficient sinonasal carcinomas and HPV-related multiphenotypic sinonasal carcinoma) will be highlighted in this review, with a discussion of several emerging entities. There is a short description of updated information for all 24 diagnostic entities included in this edition to allow the reader a snapshot of current state of knowledge, but to encourage more investigation and further broaden understanding of these diverse and rare entities.

Emerging concepts in sinonasal tumor research

PURPOSE OF REVIEW

Sinonasal malignancies are rare and understudied, often diagnosed at late stages, and may behave aggressively. This review explores investigative diagnostic, therapeutic, and scientific advances specific to sinonasal undifferentiated carcinoma (SNUC), intestinal-type adenocarcinoma (ITAC), and olfactory neuroblastoma (ONB).

RECENT FINDINGS

A number of studies have recently contributed more robust knowledge of the genetic and molecular landscapes of SNUC, ITAC, and ONB. These analyses have identified SMARCB1 and IDH2 mutations in SNUC, potentially allowing for the tumor's subdivision. Recent studies have also defined a role for induction chemotherapy in SNUC. Somatic mutations for ITAC have been identified and may be potentially targetable with FDA approved therapies. Studies defining the tumor microenvironment for ITAC and ONB have introduced the possibility of immune checkpoint inhibition for these tumor types.

SUMMARY

Studies reviewed here detail promising results of the most current and novel characterization of SNUC, ITAC, and ONB genetic and molecular landscapes, which have informed ongoing therapeutic discovery. With continued multi-institutional efforts, the field of sinonasal tumor research will achieve higher disease control and improved treatment outcomes for patients afflicted with these rare cancers.

Adamantinoma-Like Ewing Sarcoma of the Head and Neck: A Case-Series of a Rare and Challenging Diagnosis

Adamantinoma-like Ewing sarcoma (ALES) is a rare malignant tumor characterized by EWSR1::FLI1 related fusions and complex epithelial differentiation. ALES poses a tremendous diagnostic challenge owing to its resemblance to a wide variety of common head and neck malignancies. We aimed to study the clinicopathologic spectrum of ALES diagnosed at our institute. A retrospective review of the clinical and pathologic features of all EWSR1-rearranged ALES cases was performed after confirming the diagnosis. The cases lacking EWSR1 rearrangement were excluded. A total of 7 patients were analyzed. The median age was 27 years (range 7-42 years). There were 4 males and 3 female patients. Tumors were distributed as follows: maxilla (n = 2), parotid (n = 2), nasal cavity (n = 1), ethmoid/maxilla (n = 1), and thyroid (n = 1). Tumor size ranged from 2.2 to 5.5 cm. On microscopy, tumors displayed nested-lobular architecture, monomorphic cells, and interlobular fibrotic stroma. Other features included: palisading (n = 5), squamous differentiation (n = 2), keratinization (n = 1), colonisation of salivary ducts (n = 1) and thyroid follicles (n = 1), follicle-like cysts (n = 3), calcification (n = 2), necrosis (n = 3). Mitotic rate was 4-15/2 mm². On immunohistochemistry, cytokeratins (100%), p40 (100%), strong/diffuse membranous CD99 (100%), NKX2.2 (100%), Fli-1 (71%), and synaptophysin (71%) was positive. Patients received chemotherapy (n = 7) and radiotherapy (n = 4). Two patients developed recurrence at 6 and 10 months; 3 developed metastases at 0, 6, and 25 months. ALES is a rare and aggressive malignancy that mimics diverse neoplasms common in the head and neck region. Awareness of the morphologic and immunohistochemistry spectrum of this tumor is essential to avoid diagnostic errors.

Somatostatin receptor 2 is highly sensitive and specific for Epstein-Barr virus-associated nasopharyngeal carcinoma

Viruses are known drivers of head and neck squamous cell carcinomas (HNSCC), particularly Epstein-Barr virus (EBV) and human papillomavirus (HPV). Both EBV-positive nasopharyngeal carcinoma (EBVNPC) and HPV-positive oropharyngeal SCC (OPSCC) can have overlapping histomorphology and molecular signatures, including nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB) pathway mutations. A recent study showed that NFKB activation in EBVNPC drives somatostatin receptor 2 (SSTR2) expression that is detectable by immunohistochemistry and by imaging with 68-Gadolinium-DOTA-peptide radioconjugate. However, whether a similar NFKB-SSTR2 signaling mechanism exists for other virus-positive HNSCC, namely HPV-positive sinonasal carcinomas and OPSCC, remains unclear. Here we examined SSTR2 expression in a cohort of EBV-positive, HPV-positive, and virus-negative HNSCC with immunohistochemistry. SSTR2 immunohistochemistry was performed on our cohort of primary and/or metastatic EBVNPC, HPV-positive sinonasal SCC, OPSCC, HPV-negative sinonasal and oral cavity SCC, and benign tonsil and adenoid tissue. For SSTR2 staining, the extent was categorized as focal, multifocal, or diffuse, and the intensity was categorized as weak, moderate, or strong. Multifocal/diffuse SSTR2 staining of any intensity was considered positive. Among primary, recurrent, and/or undifferentiated NPC, 90% showed multifocal to diffuse strong SSTR2 expression. One HPV-positive sinonasal carcinoma showed patchy SSTR2 staining. None of the remaining HPV-positive sinonasal carcinomas, OPSCC, or oral cavity HNSCC showed significant SSTR2 staining. Overall, SSTR2 is highly sensitive and specific for EBVNPC and could represent a surrogate biomarker. Among HNSCC assessed here, we recommend testing primary NPC for SSTR2 because of its relevance for diagnosis, associated imaging modalities, and its therapeutic implications for patient care.