Neuroendocrine Neoplasms of the Sinonasal Tract: Neuroendocrine Carcinomas and Olfactory Neuroblastoma

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.

Diagnostic, Prognostic, and Predictive Role of Ki67 Proliferative Index in Neuroendocrine and Endocrine Neoplasms: Past, Present, and Future

The introduction of Ki67 immunohistochemistry in the work-up of neuroendocrine neoplasms (NENs) has opened a new approach for their diagnosis and prognostic evaluation. Since the first demonstration of the prognostic role of Ki67 proliferative index in pancreatic NENs in 1996, several studies have been performed to explore its prognostic, diagnostic, and predictive role in other neuroendocrine and endocrine neoplasms. A large amount of information is now available and published results globally indicate that Ki67 proliferative index is useful to this scope, although some differences exist in relation to tumor site and type. In gut and pancreatic NENs, the Ki67 proliferative index has a well-documented and accepted diagnostic and prognostic role and its evaluation is mandatory in their diagnostic work-up. In the lung, the Ki67 index is recommended for the diagnosis of NENs on biopsy specimens, but its diagnostic role in surgical specimens still remains to be officially accepted, although its prognostic role is now well documented. In other organs, such as the pituitary, parathyroid, thyroid (follicular cell-derived neoplasms), and adrenal medulla, the Ki67 index does not play a diagnostic role and its prognostic value still remains a controversial issue. In medullary thyroid carcinoma, the Ki67 labelling index is used to define the tumor grade together with other morphological parameters, while in the adrenal cortical carcinoma, it is useful to select patients to treated with mitotane therapy. In the present review, the most important information on the diagnostic, prognostic, and predictive role of Ki67 proliferative index is presented discussing the current knowledge. In addition, technical issues related to the evaluation of Ki67 proliferative index and the future perspectives of the application of Ki67 immunostaining in endocrine and neuroendocrine neoplasms is discussed.

The contemporary management of cancers of the sinonasal tract in adults

Sinonasal malignancies make up <5% of all head and neck neoplasms, with an incidence of 0.5-1.0 per 100,000. The outcome of these rare malignancies has been poor, whereas significant progress has been made in the management of other cancers. The objective of the current review was to describe the incidence, causes, presentation, diagnosis, treatment, and recent developments of malignancies of the sinonasal tract. The diagnoses covered in this review included sinonasal undifferentiated carcinoma, sinonasal adenocarcinoma, sinonasal squamous cell carcinoma, and esthesioneuroblastoma, which are exclusive to the sinonasal tract. In addition, the authors covered malignances that are likely to be encountered in the sinonasal tract-primary mucosal melanoma, NUT (nuclear protein of the testis) carcinoma, and extranodal natural killer cell/T-cell lymphoma. For the purpose of keeping this review as concise and focused as possible, sarcomas and malignancies that can be classified as salivary gland neoplasms were excluded.

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

Olfactory carcinoma is one of many names applied to sinonasal malignancies with histologic similarity to olfactory neuroblastoma (ONB) but cytokeratin expression or gland formation. It is unclear whether these neuroepithelial tumors represent a unified category and if they are separate from ONB and currently-recognized sinonasal carcinomas. This study aims to explore their clinicopathologic characteristics based on a large collective experience. A total of 53 sinonasal tumors with neuroepithelial differentiation were identified affecting 41 men and 12 women, median age 47 years (range: 12 to 82 y). The vast majority arose in the superior nasal cavity and presented at the high Kadish-Morita stage. Frequent histologic findings included (1) lobulated and solid growth, (2) rosettes and/or neurofibrillary stroma, (3) high-grade cytology, (4) complex, often ciliated glands, (5) nonfocal pancytokeratin expression, (6) neuroendocrine pos+itivity, and (7) variable S100-positive sustentacular cells. Twelve patients with available follow-up (48%) developed progressive disease at a median 8 months (range: 0 to 114 mo to progression), and 7 (28%) died of disease. Despite disparate historical terminology, neuroepithelial differentiation is a recurrent and recognizable histologic pattern that is associated with aggressive behavior in sinonasal tumors. While tumors with this phenotype may originate from olfactory mucosa, well-developed epithelial features warrant separation from conventional ONB and neural elements distinguish them from most sinonasal carcinomas. Although their full histogenesis remains uncertain and some heterogeneity may exist, we propose that this pattern is sufficiently distinctive to merit separate recognition as olfactory carcinoma. Use of consistent nomenclature may facilitate greater recognition of tumors with this phenotype and understanding of their pathogenesis and classification.

Neuroectodermal tumours of the sino-nasal tract: a clinicopathological study of 18 cases with a newly proposed revised classification and a brief review of literature

AIM

Sino-nasal tract tumours constitute 3% of the head and neck malignancies. Among these tumours, neuroectodermal tumours are rare with histo-morphological and immunohistochemical overlap making them a challenge for the pathologist. We included Ewing's/PNET, olfactory neuroblastoma (OFN), mucosal malignant melanomas (MMM), Melanotic neuroectodermal tumour of infancy (MNTI), small-cell neuroendocrine carcinoma (SNEC), and the newest entity Adamantinoma like Ewing's sarcoma (ALES) as part of the neuroectodermally derived tumours of the sino-nasal tract. The last three entities were added to the existing ones, which also has been emphasized in this paper.

METHODS AND RESULTS

A comprehensive analysis was done on all neuroectodermally derived tumours from 2016 to 2020. A total of 18 cases were collected, which included OFN (10 cases), SNEC (2 cases), MMM (2 cases), Ewing's/PNET (2 cases), MNTI (1 case), and ALES (1 case). The most common presentation in NE tumours was nasal obstruction (80-100%). Except for OFN, all other tumours were confined to the nasal and paranasal sinuses. 4/10 cases of OFN showed orbital extension. Cervical lymph-node metastasis was seen in 50% of cases of SNEC and MMM groups. An array of relevant immune-histochemical markers were performed. The marker expression was very subtle among the groups. On follow-up, recurrence was seen in the OFN and MMM groups in 30 and 50%, respectively. Metastasis was seen in SNEC group (100%) and OFN group (10%).

CONCLUSION

As sino-nasal neuroectodermal tumours pose a diagnostic challenge and have different therapies and are prognostically different, the pathologist must be aware of the subtle morphological, immunohistochemical clues which have been dealt with in-depth in this study.

Nasopharyngeal neuroendocrine neoplasms: Systematic review of the literature and case presentation

Most of neuroendocrine neoplasms (NENs) are located in the gastrointestinal tract and lung, and they are rarely found on the upper aero-digestive tract, which limit the current literature about nasopharyngeal NENs. This systemic review will summarize the clinical, pathological features and optimal diagnosis and management of different types of nasopharyngeal NENs (NP NENs). In-addition, we herein report an EBV negative TP53-mutated/ Rb-wild type nasopharyngeal neuroendocrine carcinoma (NEC) in a young man in which touch preparation cytology studies were integral to establishing a definitive diagnosis. To our knowledge, only very few cases of primary neuroendocrine carcinoma of the nasopharynx have been reported in the literature and the reports of these cases have not included detailed description of different types and how to optimally diagnose and manage them. In this abstract, we also highlighted the evidence about the safety of using growth factors in patients with sickle cell anemia who are receiving cytotoxic chemotherapy.

Malignant Sinonasal Tumors: Update on Histological and Clinical Management

Tumors of nasal cavity and paranasal sinuses (TuNSs) are rare and heterogeneous malignancies, presenting different histological features and clinical behavior. We reviewed the literature about etiology, biology, and clinical features of TuNSs to define pathologic features and possible treatment strategies. From a diagnostic point of view, it is mandatory to have high expertise and perform an immunohistochemical assessment to distinguish between different histotypes. Due to the extreme rarity of these neoplasms, there are no standard and evidence-based therapeutic strategies, lacking prospective and large clinical trials. In fact, most studies are retrospective analyses. Surgery represents the mainstay of treatment of TuNSs for small and localized tumors allowing complete tumor removal. Locally advanced lesions require more demolitive surgery that should be always followed by adjuvant radio- or chemo-radiotherapy. Recurrent/metastatic disease requires palliative chemo- and/or radiotherapy. Many studies emphasize the role of specific genes mutations in the development of TuNSs like mutations in the exons 4-9 of the TP53 gene, in the exon 9 of the PIK3CA gene and in the promoter of the TERT gene. In the near future, this genetic assessment will have new therapeutic implications. Future improvements in the understanding of the etiology, biology, and clinical features of TuNSs are warranted to improve their management.

Lobular to Lobule: Metastatic Breast Carcinoma to Olfactory Neuroblastoma

Tumor-to-tumor metastasis (TTM) is a rare, but well-described phenomenon occurring in patients with multiple synchronous or metachronous primary malignancies. Olfactory neuroblastoma (ONB) is a rare malignant, neuroectodermal sinonasal tract tumor that occurs within the ethmoid sinus involving the cribriform plate. Very few cases of ONB have been documented to metastasize to other primary malignancies, but the reverse scenario is exceptional. During an evaluation for anosmia, a right nasal polyp was identified on imaging and endoscopy in a 66-year-old woman, with a polypectomy performed. Histologic examination showed classical features of a low-grade olfactory neuroblastoma, but within the tumor were isolated epithelioid cells which were strongly pancytokeratin immunoreactive. Review of the clinical history revealed lobular breast carcinoma treated 10 years earlier. Further evaluation with immunohistochemistry showed strong and diffuse nuclear estrogen and progesterone receptor reactivity, along with GATA3. These results confirmed TTM of an invasive lobular breast carcinoma to ONB. By employing a limited immunohistochemistry panel for all small round blue cell tumors that includes pancytokeratin, p40, S100 protein, SOX10, synaptophysin, desmin, CD99, and CD45, one is able to more accurately diagnose the classical tumor types, while also showing potentially unusual tumor features or exceptionally rare events like metastatic lobular breast carcinoma to ONB.

Unusual Presentation of a Sphenoidal Sinus Neuroendocrine Tumor: A Case Report and Review of Literature

Neuroendocrine tumors (NETs) have a heterogeneous pathology and indolent behavior, with the most common location being the gastrointestinal tract and then the lungs. The head and neck are rare sites of NET presentation with varied clinical signs and symptoms, which occasionally delay the diagnosis, thereby leading to an advanced stage at presentation. We present a rare case of paranasal sinus small cell neuroendocrine tumor and perform a review of the literature. A 71-year-old man presented with continuous bleeding from the left nostril and nasal congestion without any prior medical history. Clinical examination revealed nasal congestion, rhinorrhea, postnasal drip, and active bleeding. The laboratory data were within normal limits. Imaging studies showed a left sphenoid sinus mass extending to the left ethmoid sinus with a break in the cribriform plate encephalocele. An enlarged lymph node measuring 2.2 cm was noted in the left neck and supraclavicular region. The evaluation through stereotactic endoscopic sinus surgery and biopsy revealed left nasopharyngeal, sphenoid sinus, and ethmoid sinus masses. Pathologic biopsy findings were consistent with high-grade, malignant, small, round blue cell tumors. Immunohistochemical analysis confirmed high-grade small cell neuroendocrine carcinoma. The patient was diagnosed with stage IV (TXN2bM0, T: tumor size, N: lymph node, M: metastasis) high-grade neuroendocrine tumor of the left paranasal sinus. He was treated with concurrent chemoradiation therapy with two cycles of etoposide and cisplatin and radiation therapy with proton beam radiation therapy followed by two cycles of adjuvant etoposide cisplatin chemotherapy. The patient showed a good response to the treatment, as confirmed using imaging. He is currently being regularly followed up with serial imaging.

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.

Mixed olfactory neuroblastoma and neuroendocrine carcinoma: An unusual case report and literature review

Background:

The aim of the study was to present a case of mixed olfactory neuroblastoma (ONB) and carcinoma, an extremely rare tumor with only a few cases in the published literature.

Case Description:

An otherwise healthy 27-year-old male presented with sinus complaints, headache, and unilateral eye discharge. Imaging and endoscopy revealed a mass presumed to represent a juvenile nasopharyngeal angiofibroma. Unexpectedly, the final pathology report revealed high grade mixed ONB and carcinoma. This tumor is the sixth and youngest documented patient with mixed ONB and carcinoma.

Conclusion:

Physicians should remain vigilant for the possibility of malignancy in their approach to nasal cavity masses, even in young otherwise healthy patients. Careful review of the immunohistopathology should also be taken, as mixed olfactory tumors such as these are aggressive, rare entities that require multidisciplinary oncologic care.

Epithelial cell function and remodeling in nasal polyposis

OBJECTIVE

To review the latest discoveries on airway epithelial cell diversity and remodeling in type 2 inflammation, including nasal polyposis.

DATA SOURCES

Reviews and primary research manuscripts were identified from PubMed, Google, and Bioarchives, using the search words airway epithelium, nasal polyposis, or chronic rhinosinusitis with nasal polyposis AND basal cell, ciliated cell, secretory cell, goblet cell, neuroendocrine cell, pulmonary neuroendocrine cell, ionocyte, brush cell, solitary chemosensory cell, microvillus cell, or tuft cell.

STUDY SELECTIONS

Studies were selected based on novelty and likely relevance to airway epithelial innate immune functions or the pathobiology of type 2 inflammation.

RESULTS

Airway epithelial cells are more diverse than previously appreciated, with specialized subsets, including ionocytes, solitary chemosensory cells, and neuroendocrine cells that contribute to important innate immune functions. In chronic rhinosinusitis with nasal polyposis, the composition of the epithelium is significantly altered. Loss of ciliated cells and submucosal glands and an increase in basal airway epithelial progenitors leads to loss of innate immune functions and an expansion of proinflammatory potential. Type 2 cytokines play a major role in driving this process.

CONCLUSION

Airway epithelial remodeling in chronic rhinosinusitis is extensive, leading to loss of innate immune function and enhanced proinflammatory potential. The mechanisms driving airway remodeling and its sequelae deserve further attention before restitution of epithelial differentiation can be considered a reasonable therapeutic target.

Metastatic retroperitoneal tumor from a non-functional neuroendocrine neoplasia of the left ethmoid-nose-orbitary region: Case report and short review of literature

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NENs are rare tumors with extremely variable behavior: they are difficult to diagnose, especially if biologically inactive.

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NENs can originate from any epithelial organ and present unusual metastases.

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NEN surgery is a valid treatment and a necessary tool for correct diagnosis.

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NEN classification is evolving and being discussed.

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Careful collection of anamnestic data and a correct analysis of patients’ symptoms can be a valuable resource.

Introduction

NeuroEndocrine Neoplasms (NENs) are rare and can originate from any epithelial organ. We describe a very rare case of retroperitoneal metastasis from a non-functioning neuroendocrine tumor of the ethmoid region and focus on the various issues related to NENs, from their nosological classification up to the most recent acquisitions in the diagnostic and therapeutic field.

Presentation of case

A woman presented with a mass in the right retroperitoneal area that infiltrated liver and kidney. The anamnestic data showed a previous undifferentiated small cell tumor of the left ethmoid-nasal-orbital region. The mass was removed surgically and the definitive histological examination revealed a non-functioning undifferentiated malignant small cell neoplasm.

Discussion

NENs represent a chapter of oncology whose systematization remains difficult. The lack of hormonal syndrome in Biologically Inactive Neuroendocrine Tumors (BINTs) may delay the diagnosis. Clinical manifestations relate to the size and location of the neoplasm. Small cell NeuroEndocrine Carcinoma (NEC) of the ethmoid-nose-orbital region is an extremely rare occurrence and generally the most frequent metastatic localization is represented by the larynx.

Conclusion

This case highlights the contradictions typical of NENs and only new scientific acquisitions in the histopathological field can help us in the future. Surgery remains the only possibility of treatment and diagnosis of large masses of inactive NENs. This is the only case in the world of metastasis from NEC of the nose-orbital region in the retroperitoneum.

[Neuroendocrine neoplasms of the auditory, olfactory, and visual sensory organs]

Neuroendocrine neoplasms (NENs) are infrequent in sensory organs. There are well-differentiated neuroendocrine neoplasms that should be classified as neuroendocrine tumors, in analogy to their gastrointestinal counterparts, however the nomenclature is inconsistent. The best defined entities are neuroendocrine tumors in the middle ear and ectopic pituitary adenoma in the sphenoid region. Poorly differentiated NENs most often arise in the olfactory organ and nasal cavity that are represented by olfactory neuroblastomas and poorly differentiated neuroendocrine carcinomas. They have several mimickers such as the sinonasal undifferentiated carcinoma, poorly differentiated squamous cell carcinoma, mucosal malignant melanoma, rhabdomyosarcoma, Ewing sarcoma/primitive neuroectodermal tumor and non-Hodgkin lymphoma.

Mixed Olfactory Neuroblastoma and Adenocarcinoma with In Situ Neuroendocrine Hyperplasia

Olfactory neuroblastoma (ONB) is a rare malignant neoplasm arising from the superior aspect of the nasal vault. Cases are characterised by insidious clinical presentation and high rates of recurrence despite surgical resection and adjuvant radiotherapy. There are a small number of reports showing ONB with divergent epithelial or ganglionic differentiation, and ONB has also been found to coincide with adenocarcinoma. We present a case of mixed ONB with adenocarcinoma. The clinical presentation was unusual, with a tonic-clonic seizure preceded by chronic headache and anosmia. Imaging revealed a mass extending from the olfactory recess of the left nasal cavity through the cribriform plate to the anterior cranial fossa. The pathology demonstrated intraepithelial neuroendocrine cell hyperplasia in the left olfactory groove. This finding provides a unique insight into the cellular origin of this rare tumour, and appears to confirm the theory that ONB arises from neural stem cells in the olfactory neuroepithelium. Despite radical treatment, the patient suffered a distant recurrence within 1 year of treatment, which underlines the aggressive nature of this tumour.

Endonasal endoscopic resection of olfactory neuroblastoma: an 11-year experience

OBJECTIVE

Olfactory neuroblastoma (ONB) is a rare malignant neoplasm of the sinonasal cavity. Surgery has been and remains a mainstay of treatment for patients with this tumor. Open craniofacial resections have been the treatment of choice for many decades. More recently, experience has been growing with endoscopic approaches in the management of patients with ONB. The object of this study is to report the authors’ experience over the past 11 years with ONB patients treated with purely endonasal endoscopic techniques.

METHODS

The authors performed a retrospective chart review of 20 consecutive patients with ONB who underwent a completely endonasal endoscopic approach for an oncological tumor resection at their institution between January 2006 and January 2017. Patient demographics, tumor stage, pathological grade, frozen section analysis, permanent margin assessment, perioperative complications, postoperative therapy, length of follow-up, and outcomes at last follow-up were collected and analyzed.

RESULTS

Eighteen patients presented with newly diagnosed disease, with a modified Kadish stage of A in 2 cases, B in 3, C in 11, and D in 2. Two patients presented with recurrent tumors. An average of 25.3 specimens per patient were examined by frozen section analysis. Although analysis of intraoperative frozen section margins was negative in all but 1 case, microscopic foci of tumor were found in 7 cases (35%) on permanent histopathological analysis. Perioperative complications occurred in 7 patients (35%) including 1 patient who developed a cerebrospinal fluid leak; there were no episodes of meningitis. All but 1 patient received postoperative radiotherapy, and 5 patients received postoperative chemotherapy. With a mean follow-up of over 5 years, 19 patients were alive and 1 patient died from an unrelated cause. There were 2 cases of tumor recurrence. The 5-year overall, disease-specific, and recurrence-free survival rates were 92.9%, 100%, and 92.9%, respectively.

CONCLUSIONS

The current results provide additional evidence for the continued use of endoscopic procedures in the management of this malignancy.

INSM1 is a Sensitive and Specific Marker of Neuroendocrine Differentiation in Head and Neck Tumors

The head and neck is the site of a wide and sometimes bewildering array of neuroendocrine (NE) tumors. Although recognition of NE differentiation may be necessary for appropriate tumor classification and treatment, traditional NE markers such as synaptophysin, chromogranin, and CD56 are not always sufficiently sensitive or specific to make this distinction. Insulinoma-associated protein 1 (INSM1) is a novel transcription factor that has recently demonstrated excellent sensitivity and specificity for NE differentiation in various anatomic sites, but has not yet been extensively evaluated in tumors of the head and neck. We performed INSM1 immunohistochemistry on NE tumors (n=97) and non-NE tumors (n=626) across all histologic grades and anatomic subsites of the head and neck. INSM1 was positive in all types of head and neck NE tumors evaluated here (99.0% sensitivity), including middle ear adenoma, pituitary adenoma, paraganglioma, medullary thyroid carcinoma, olfactory neuroblastoma, small cell carcinoma, large cell NE carcinoma, and sinonasal teratocarcinosarcoma. Notably, it was positive in the vast majority of high-grade NE malignancies (95.8% sensitivity). INSM1 also was negative in almost all non-NE tumors (97.6% specificity) with the highest rates of reactivity in alveolar rhabdomyosarcoma and SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily B, member 1 (SMARCB1)-deficient sinonasal carcinoma. These findings confirm that INSM1 may be used as a standalone first-line marker of NE differentiation for tumors of the head and neck.

Ectopic Cushing's syndrome secondary to olfactory neuroblastoma

We present the case of a patient with Cushing's syndrome secondary to ectopic ACTH secretion. A MR of the head showed a left-sided nasal mass extending down from the cribriform plate. The patient underwent endoscopic resection with nearly complete removal of the mass. Histological examination showed an ACTH-secreting olfactory neuroblastoma (ONB). The patient's cortisol levels returned to normal range after surgery and have remained normal for over a year. ONB is a rare cause for ectopic ACTH secretion. This case highlights the diagnostic and management difficulties in patients with ectopic ACTH secretion, and provides a brief review of ONB.

Genetic profiling of poorly differentiated sinonasal tumours

The sinonasal cavities harbour a variety of rare tumour types. Many carry a poor prognosis while therapeutic options are limited. Histopathological classification can be difficult, especially for poorly differentiated tumours such as olfactory neuroblastoma (ONB), sinonasal neuroendocrine carcinoma (SNEC) and sinonasal undifferentiated carcinoma (SNUC). We analysed Affymetrix OncoScan genome-wide copy number profiles of these three tumour types, both as originally diagnosed and as regrouped by their cytokeratin (Ck) and neuroendocrine (Ne) expression pattern, aiming to find a relation between phenotype and genotype. According to the original histopathological classification our series consisted of 24 ONB, 11 SNEC and 19 SNUC, while immunohistochemistry indicated 11 Ck−Ne+/ONB, 18 Ck+Ne+/SNEC, 24 Ck+Ne−/SNUC, and 1 Ck−Ne−/unclassified. As originally diagnosed, the three tumour types showed similar copy number profiles. However, when regrouped by Ck/Ne immunostaining we found a distinct set of gains and losses; Ck−Ne+/ONB harboured few and predominantly whole chromosomes abnormalities, Ck+Ne+/SNEC carried both gains and losses in high frequency, and Ck+Ne−/SNUC showed mostly gains. In addition, each tumour carried a number of unique chromosomal deletions. Genome-wide copy number profiling supports the value of immunohistochemical CkNe staining of ONB, SNEC and SNUC for tumour classification, which is important for prognosis and therapeutic decision-making.

Neuroectodermally Derived Neoplasm of Tonsil: Difficulty in Histomorphological Diagnosis

Esthesioneuroblastomas are rare neuroectodermally derived neoplasms occurring in the upper nasal septum or cribriform plate. They have been rarely reported in other sites, when they are called ectopic esthesioneuroblastomas. Due to the scarcity of reports, publications and molecular/genetic studies of these tumours, their diagnosis is likely to be missed when they are ectopic. Similar to the case report in this journal by Zahedi et al., we had a case of neuroectodermally derived neoplasm of the tonsil, which was difficult to diagnose, due to the site of occurrence being unknown for these tumours.

Differentiation of olfactory neuroblastomas from nasal squamous cell carcinomas using MR diffusion kurtosis imaging and dynamic contrast-enhanced MRI

PURPOSE

To evaluate the use of magnetic resonance (MR) diffusion kurtosis imaging (DKI) and dynamic contrast-enhanced MR imaging (DCE-MRI) in the differentiation of olfactory neuroblastomas (ONBs) from squamous cell carcinomas (SCCs).

MATERIALS AND METHODS

DKI and DCE-MRI were performed in 17 patients with ONBs and 23 patients with SCCs on a 3T MR scanner. Parameters derived from DKI and DCE-MRI were measured and compared between ONBs and SCCs using an independent samples t-test. The sensitivity, specificity, accuracy, positive predictive values (PPV), negative predictive values (NPV), and the area under the receiver operating characteristic (ROC) curve were determined.

RESULTS

The mean kurtosis (K) value of ONBs was significantly higher than that of SCCs (P < 0.001), and the mean fractional volume in the extravascular extracellular space (V_e ) value of ONBs was lower than that of SCCs (P < 0.001). The ROC curve analyses yielded a cutoff K value of 0.953, with a sensitivity of 94.1%, a specificity of 69.6%, and an accuracy of 80.0%; the cutoff V_e value was 0.493, with a sensitivity of 70.6%, a specificity of 95.7%, and an accuracy of 85.0%. A parallel test with K value >0.953 or V_e value ≤0.493 achieved a sensitivity of 94.1%, a specificity of 100.0%, and an accuracy of 97.5% for differentiating ONBs from SCCs.

CONCLUSION

The K value of DKI and V_e value of DCE-MRI have potential use in the differentiation of ONBs and SCCs.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:354-361.