Algorithmic approach to neuroendocrine tumors in targeted biopsies: Practical applications of immunohistochemical markers

Medullary Thyroid Carcinoma and Clinical Outcomes in Heterozygous Carriers of the RET K666N Germline Pathogenic Variant

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor of the thyroid parafollicular C-cells associated with activating mutations in the rearranged during transfection (RET) kinase proto-oncogene. We report the clinical outcomes of a family with a rare germline RET K666N pathogenic variant discovered incidentally by genetic testing performed for breast cancer risk stratification in an asymptomatic 24-year-old woman. Subsequent genetic testing identified the same pathogenic variant in her 21-year-old sister, 60-year-old father, and 84-year-old paternal grandmother. The proband and her sister had no biochemical or imaging evidence of MTC. The 60-year-old father had mildly elevated serum calcitonin and multiple thyroid nodules on ultrasound. Fine-needle aspirate thyroid biopsy cytology suggested MTC so he underwent total thyroidectomy. Surgical pathology demonstrated bilateral subcentimeter foci of MTC and C-cell hyperplasia. The 84-year-old grandmother was also found to have multiple thyroid nodules and elevated calcitonin but declined further evaluation. There was no biochemical evidence of other multiple endocrine neoplastic type 2 (MEN2)-associated tumors (ie, parathyroid adenoma, pheochromocytoma) in the family. These data, along with prior rare reports in the literature, suggest that monoallelic germline RET K666N pathogenic variants carry a risk of familial MTC that demonstrate age-dependent expressivity but low penetrance of other MEN2 tumors in affected individuals.

PD-1 blockade plus cisplatin-based chemotherapy in patients with small cell/neuroendocrine bladder and prostate cancers

Small cell neuroendocrine cancers share biologic similarities across tissue types, including transient response to platinum-based chemotherapy with rapid progression of disease. We report a phase 1b study of pembrolizumab in combination with platinum-based chemotherapy in 15 patients with stage III-IV small cell bladder (cohort 1) or small cell/neuroendocrine prostate cancers (cohort 2). Overall response rate (ORR) is 43% with two-year overall survival (OS) rate of 86% (95% confidence interval [CI]: 0.63, 1.00) for cohort 1 and 57% (95% CI: 0.30, 1.00) for cohort 2. Treatment is tolerated well with grade 3 or higher adverse events occurring in 40% of patients with no deaths or treatment cessation secondary to toxicity. Single-cell and T cell receptor sequencing of serial peripheral blood samples reveals clonal expansion of diverse T cell repertoire correlating with progression-free survival. Our results demonstrate promising efficacy and safety of this treatment combination and support future investigation of this biomarker. This study was registered at ClinicalTrials.gov (NCT03582475).

Practical hints for the diagnosis of mixed neuroendocrine-non-neuroendocrine neoplasms of the digestive system

In this editorial, a comment on the article by Díaz-López et al published in the recent issue of the 2024 is provided. We focus on the practical implications critical for providing a correct and complete diagnosis of mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) in the gastrointestinal system. The diagnosis of MiNEN begins with the recognition of neuroendocrine features in one component of a biphasic tumor. The non-neuroendocrine counterpart can be virtually represented by any neoplastic type, even though the most frequent histologies are glandular and squamous. However, qualification of the neuroendocrine component requires histological and immunohistochemical confirmation. Neuroendocrine tumors are characterized by a peculiar architectural organization and bland nuclei with granular "salt and pepper" chromatin. Although neuroendocrine carcinomas have multiple and variable presentations, they typically show a solid or organoid architecture. The histological aspect needs to be confirmed by immunohistochemistry, and a diagnosis is confirmed whenever the expression of keratin and neuroendocrine markers is observed. Once both histopathological and immunohistochemical features of neuroendocrine neoplasms are identified, it is important to consider the three major pitfalls of MiNEN diagnostics: (1) Entrapment of neuroendocrine non-neoplastic cells within the tumor mass; (2) Differential diagnosis with amphicrine neoplasms; and (3) Differential diagnosis of tumors that partially express neuroendocrine markers. According to the current guidelines for diagnosing digestive MiNEN, each component must represent at least 30% of the entire neoplastic mass. Although the high-grade histopathological subtype frequently determines disease prognosis, both components can significantly affect prognosis. Thus, if one of the components, either neuroendocrine or non-neuroendocrine, does not fulfill the volumetric criteria, the guidelines still encourage reporting it. These strict criteria are essential for correctly recognizing and characterizing digestive MiNENs. This task is essential because it has prognostic relevance and substantial potential value for guiding further studies in this field. In the future, systematic analyses should be performed to validate or reconsider the current 30% cutoff value.

Various Markers of Neuroendocrine Tumor: A Narrative Review

Neuroendocrine tumors (NETs) are uncommon tumors that develop from specialized endocrine cells. Thyroid medullary carcinoma, phaeochromocytomas, pituitary tumors, carcinoid, and gastroenteropancreatic NET are just a few examples of the diverse group known as NET. In recent times, they have garnered significant interest due to their ease of palliation and ability to reveal the long-term impact of the specific hormone raised. Neuroendocrine indicators, particularly chromogranin A, are very helpful in the diagnostic process. Accurate biomarkers that can be employed for NET diagnosis, prognosis and follow-up, therapy stratification, and treatment response evaluation are greatly needed. Due to the great diversity of neuroendocrine neoplasms, particular biomarkers must be developed in order to diagnose, treat, and identify them. The several NET biomarkers covered in this review will aid in the fight against this uncommon illness.

Diagnostic Approaches to Neuroendocrine Neoplasms of Unknown Primary Site

ABSTRACT

Neuroendocrine tumors (NETs) are relatively uncommon heterogeneous neoplasms arising from endocrine and neuronal origin cells showing highly variable clinical behavior. By the time these tumors are discovered, up to 14% of patients with histologically proven NETs have metastasis, with the liver as the most frequently affected organ. Sometimes, no known primary site can be identified via routine imaging. Neuroendocrine tumors of unknown origin carry a poorer prognosis (compared with metastatic NETs with a known primary site) because of a lack of tailored surgical intervention and appropriate medical therapy (eg, chemotherapy or targeted therapy). A multimethod approach is frequently used in the trial to accurately determine the primary site for NETs of unknown primary sites and may include clinical, laboratory, radiological, histopathological, and surgical data. New molecular techniques using the genomic approach to identify the molecular signature have shown promising results. Various imaging modalities include ultrasound, computed tomography (CT), dual-energy CT, magnetic resonance imaging, and functional and hybrid imaging (positron emission tomography/CT, positron emission tomography/magnetic resonance imaging); somatostatin receptor imaging with new tracers is frequently used in an attempt for localization of the primary site.

A clinical perspective on ectopic Cushing's syndrome

Cushing's syndrome (CS) refers to the clinical features of prolonged pathological glucocorticoid excess. About 10-20% of individuals with CS have ectopic CS (ECS), that is, an adrenocorticotropin (ACTH)-producing tumour outside the pituitary gland. ACTH-secreting neuroendocrine neoplasia (NENs) can arise from many organs, although bronchial NEN, small cell lung cancer (SCLC), pancreatic NEN, thymic NEN, medullary thyroid cancer (MTC), and pheochromocytoma are the most common. Patients with ECS frequently present with severe hypercortisolism. The risk of life-threatening complications is high in severe cases, unless the hypercortisolism is effectively treated. A good outcome in ECS requires a methodical approach, incorporating prompt diagnosis, tumour localization, control of cortisol excess, and resection of the primary tumour when possible.

Incidental Diagnosis of a Primary Pure "Mixed" Ovarian Carcinoid: Clinicopathological Report and Concise Review of the Recent Series

Primary ovarian carcinoid tumors (POCT) are well-differentiated neuroendocrine neoplasms and account for <0.1% of ovarian tumors. POCT usually arise in the context of mature cystic teratoma; however, pure primary ovarian carcinoids without teratomatous or mucinous elements are very rare. We present a case of a 54-year-old woman that underwent total laparoscopic hysterectomy and bilateral salpingo-oophorectomy because of endometrial hyperplasia without atypia. The ovaries were macroscopically normal. Pathology report revealed a primary ovarian carcinoid with mixed trabecular and insular growth patterns. Immunohistochemical was positive for chromogranine A, synaptophysin, and CDX2. The Ki-67 index was <1%. To exclude a metastatic carcinoid to the ovary, a Ga-68 PET/CT was performed. This case highlights the microscopic and immunohistochemical characteristics of pure POCT and potential pitfalls in their differentiation from metastatic carcinoids. In addition, differential characteristics of primary and metastatic ovarian carcinoids are discussed.

[Unification of pathomorphological examination of patients with neuroendocrine tumors of the pituitary gland. Controversial issues of the new classification]

The progressive improvement of the classification using modern analytical methods is an essential tool for the development of precise and personalized approaches to the treatment of pituitary adenomas. In recent years, endocrinologists have witnessed evolutionary changes that have occurred in the histopathological identification of pituitary neoplasms, revealing new possibilities for studying tumorigenesis and predicting biological behavior.The paper considers the historical aspects of the gradual improvement of the classification of pituitary adenomas, as well as the new international 2022 WHO classification, according to which pituitary adenomas are included in the list of neuroendocrine tumors (PitNETs) to reflect the biological aggressiveness of some non-metastatic pituitary adenomas. The characteristics of pituitary adenoma are presented, as well as a list of histological subtypes of aggressive neuroendocrine tumors of the pituitary gland, marked by the main potentials for invasive growth, an increased risk of recurrence and a negative clinical prognosis.The expediency of changing the definition of «pituitary adenoma» to «neuroendocrine tumor» is discussed. It is emphasized that the introduction of a unified clinical, laboratory and morphological protocol into national clinical practice will help provide comparable comparative studies on the prognosis of the disease and the effectiveness of secondary therapy and also contribute to adequate management of potentially aggressive PitNETs.

Successful management of a rare case of gallbladder neuroendocrine carcinoma with tumor thrombi

A gallbladder neuroendocrine neoplasm (GB‑NEN) is a bizarre heterogeneous neoplasm arising from neuroendocrine cells, which are present in minimal amounts on the GB mucosa either due to conversion of undifferentiated stem cells, chronic inflammation and resulting in pathological metaplasia or switching of GB adenocarcinoma to neuroendocrine one. Among all the GB malignancies, GB-NEN accounts for approximately 2.1%. A 41-year-old lady presented with right upper abdomen pain and distension for 2 weeks. Contrast CT showed heterogeneously enhancing wall thickening involving fundus-body of the GB with large exophytic component involving segments IV/V of liver, peripheral enhancement and central low attenuating necrotic areas. Middle hepatic and left branch of portal vein was filled with enhancing lesion, tumor thrombi. She underwent left trisectionectomy followed by adjuvant chemotherapy. Postoperative biopsy reported as poorly differentiated unifocal small cell GB-neuroendocrine carcinomas (GB-NEC). Resected margins were free of tumor with periportal lymph nodes negative for tumor. Follow-up PET-CT after six months of treatment completion shows no tumor recurrence or metastases. She has completed 12 months following the surgery and is asymptomatic. As the occurrence of GB-NEC is rare, there are little data regarding etiology, pathogenesis, treatment and prognosis of it. Even though metastasis is early and most frequent to lymph nodes, liver, lung and peritoneum, the presence of tumor thrombus in GB-NEC is rarely reported. Though most reports suggest very poor outcomes, radical surgery followed by adjuvant chemotherapy can yield good short-term results as seen in this case.

Neuroendocrine Tumors: Genomics and Molecular Biomarkers with a Focus on Metastatic Disease

Neuroendocrine tumors (NETs) are considered rare tumors that originate from specialized endocrine cells. Patients often present with metastatic disease at the time of diagnosis, which negatively impacts their quality of life and overall survival. An understanding of the genetic mutations that drive these tumors and the biomarkers used to detect new NET cases is important to identify patients at an earlier disease stage. Elevations in CgA, synaptophysin, and 5-HIAA are most commonly used to identify NETs and assess prognosis; however, new advances in whole genome sequencing and multigenomic blood assays have allowed for a greater understanding of the drivers of NETs and more sensitive and specific tests to diagnose tumors and assess disease response. Treating NET liver metastases is important in managing hormonal or carcinoid symptoms and is imperative to improve patient survival. Treatment for liver-dominant disease is varied; delineating biomarkers that may predict response will allow for better patient stratification.

All Together Now: Standardization of Nomenclature for Neuroendocrine Neoplasms across Multiple Organs

Neuroendocrine neoplasms (NENs) span virtually all organ systems and exhibit a broad spectrum of behavior, from indolent to highly aggressive. Historically, nomenclature and grading practices have varied widely across, and even within, organ systems. However, certain core features are recapitulated across anatomic sites, including characteristic morphology and the crucial role of proliferative activity in prognostication. A recent emphasis on unifying themes has driven an increasingly standardized approach to NEN classification, as delineated in the World Health Organization's Classification of Tumours series. Here, we review recent developments in NEN classification, with a focus on NENs of the pancreas and lungs.

The Complex Histopathological and Immunohistochemical Spectrum of Neuroendocrine Tumors-An Overview of the Latest Classifications

Neuroendocrine neoplasms (NENs) originate from the neuroendocrine cell system, which may either take the shape of organoid cell aggregations or be composed of dispersed cells across various organs. Therefore, these tumors are heterogenous regarding the site of origin, functional status, degree of aggressiveness, and prognosis. When treating patients with neuroendocrine tumors, one of the most significant challenges for physicians is determining the correct tumor grade and thus classifying patients into risk categories. Over the years, the classification of these tumors has changed significantly, often causing confusion due to clinical, molecular, and immunohistochemical variability. This review aims to outline the latest NENs classifications regardless of their site of origin. Thus, an overview of the key histopathological and immunohistochemical characteristics of NENs could pave the way to validate possible predictive and prognostic markers and also guide the therapeutic conduct.

Imaging of neuroendocrine neoplasms of the male GU tract

Male genitourinary neuroendocrine neoplasms (GU-NENs) are rare, without any definite imaging characteristics. The WHO classified neuroendocrine neoplasms in the 2016 classification of the tumors of the urinary tract and genital organs along with other GU tumors; however, no pathologic grading system is available as published for gastroenteropancreatic neuroendocrine neoplasms. Often a multimodality approach using cross-sectional imaging techniques, such as molecular imaging and histopathology are implemented to arrive at the diagnosis. This article provides a review of the pathology and imaging features of the male GU-NENs.

Pure small cell neuroendocrine carcinoma of urinary bladder: A case report

Small cell neuroendocrine carcinoma of the bladder is rare. We report a case of small cell carcinoma of the bladder with extensive regional lymph node metastases who underwent radical cystoprostatectomy and subsequent adjuvant systemic chemotherapy and chemoradiotherapy.

Mixed neuroendocrine-non-neuroendocrine neoplasms of the digestive system: A mini-review

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are rare mixed tumors containing both neuroendocrine (NE) and non-NE components. Each component must occupy at least 30% of the tumor volume by definition. Recent molecular evidence suggests MiNENs are clonal neoplasms and potentially harbor targetable mutations similar to conventional carcinomas. There have been multiple changes in the nomenclature and classification of MiNENs which has created some confusion among pathologists on how to integrate the contributions of each component in a MiNEN, an issue which in turn has resulted in confusion in communication with front-line treating oncologists. This mini review summarizes our current understanding of MiNENs and outline diagnosis, prognosis, and management of these neoplasms. The authors emphasize the importance of treating the most aggressive component of the tumor regardless of its percentage volume.

Appendiceal Well-Differentiated Neuroendocrine Tumors: A Single-Center Experience and New Insights into the Effective Use of Immunohistochemistry

Background. Appendiceal well-differentiated neuroendocrine tumor is the most common histological type of appendiceal tumor. The majority of tumors are found incidentally at the tip of the appendix, with few exceptions. Due to its primarily indolent nature, this entity presents unique pathological challenges, particularly in the appropriate use of immunohistochemistry which this study aims to clarify. Patients and methods. Patients diagnosed at University Health Network (Canada) between 2005–2019 were selected and reviewed. Results. We identified 70 patients and sex distribution was female 60%; median age 36.5 years. Among them, 63 patients underwent appendectomy, and seven had initial right hemicolectomy for non-appendix lesions. Mean tumor size was 5.0 mm. Tumor extent was submucosa (15%); muscularis propria (34%); subserosa or mesoappendix (42%); visceral peritoneum (8%). All were clinically non-functional and negative for nodal and distant metastasis. Ninety percent of tumors were WHO Grade 1; 10% were WHO Grade 2. Immunohistochemically, an average of six stains were performed per patient. Nearly all tumors were positive for chromogranin A, synaptophysin, CAM5.2, and CDX2. MIB-1 staining was < 3% in 58/63 tumors. Other immunohistochemical stainings performed were hormonal markers (serotonin, glucagon, pancreatic peptide, peptide YY). Subsequent right hemicolectomy was performed on five patients. All were followed up (median 4 years 8 months), and all were alive without recurrence except for one patient who died of another comorbidity. Conclusion. Tumors that are small, localized, and of low grade can be reasonably exempt from an extensive immunohistochemical panel in the absence of non-typical clinical and morphological features.

Metastatic Neuroendocrine Neoplasms of Unknown Primary: Clues from Pathology Workup

Simple Summary

While most neuroendocrine neoplasms are indolent and slow-growing tumors, subsets of cases will spread beyond the tissue of origin. Given the rather slow progress, some lesions are incidentally discovered as metastatic deposits rather than primary masses. In these cases, a biopsy is often taken to allow the pathologist to identify the tumor type and possibly the primary tumor site via microscopic examination. In this review, the authors present a simplified guide on how to approach metastatic neuroendocrine tumors from a pathologist’s perspective.

Abstract

Neuroendocrine neoplasms (NENs) are diverse tumors arising in various anatomical locations and may therefore cause a variety of symptoms leading to their discovery. However, there are instances in which a NEN first presents clinically as a metastatic deposit, while the associated primary tumor is not easily identified using conventional imaging techniques because of small primary tumor sizes. In this setting (which is referred to as a “NEN of unknown primary”; NEN-UP), a tissue biopsy is often procured to allow the surgical pathologist to diagnose the metastatic lesion. If indeed a metastatic NEN-UP is found, several clues can be obtained from morphological assessment and immunohistochemical staining patterns that individually or in concert may help identify the primary tumor site. Herein, histological and auxiliary analyses of value in this context are discussed in order to aid the pathologist when encountering these lesions in clinical practice.

Double Ki-67 and synaptophysin labeling in pancreatic neuroendocrine tumor biopsies

BACKGROUND

Pancreatic neuroendocrine tumors (PanNETs) are frequently detected on endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) specimens. The conventional methods for evaluating the Ki-67 labeling index (Ki67LI) in EUS-FNAB specimens are laborious, and their results are difficult to interpret. More practical and easy methods for evaluating the Ki67LI in PanNETs from EUS-FNAB specimens is increasing in need.

METHODS

We used double Ki-67 and synaptophysin (double Ki-Syn) antibody cocktail; Ki67LI, total Ki-67 positive cells, and total tumor cells were counted and compared with those detected on conventional single Ki-67 immunostaining (single Ki-67) of 96 PanNETs [Grade 1 (G1), 68 cases (71%); G2, 26 (27%); G3, 2 (2%)] from EUS-FNAB specimens.

RESULTS

The tumor grading between double Ki-Syn and single Ki-67 immunolabeling was highly concordant (correlation, 0.95; Fisher's exact test, P < 0.001). Seven EUS-FNAB specimens (7%) had discrepant results, of which 2 were removed through surgical resection and showed the same tumor grade as that detected on double Ki-Syn immunolabeling. Fifty-four specimens (56%) had higher Ki-67 positive tumor cell counts on single Ki-67 immunolabeling. Sixty-two specimens (65%) had higher total tumor cell counts on double Ki-Syn immunolabeling. The number of specimens with less than 500 total counted tumor cells were significantly reduced when double Ki-Syn immunolabeling was applied [P = 0.046; single Ki-67, 17 specimens (18%); double Ki-Syn, 9 specimens (9%)].

CONCLUSION

Double Ki-Syn immunolabeling enables the accurate counting of the number of proliferating tumor cells without including inflammatory and contaminant epithelial cells compared with single Ki-67 immunolabeling in PanNETs from EUS-FNAB specimens.

Overview of the 2022 WHO Classification of Paragangliomas and Pheochromocytomas

This review summarizes the classification of tumors of the adrenal medulla and extra-adrenal paraganglia as outlined in the 5th series of the WHO Classification of Endocrine and Neuroendocrine Tumors. The non-epithelial neuroendocrine neoplasms (NENs) known as paragangliomas produce predominantly catecholamines and secrete them into the bloodstream like hormones, and they represent a group of NENs that have exceptionally high genetic predisposition. This classification discusses the embryologic derivation of the cells that give rise to these lesions and the historical evolution of the terminology used to classify their tumors; paragangliomas can be sympathetic or parasympathetic and the term pheochromocytoma is used specifically for intra-adrenal paragangliomas that represent the classical sympathetic form. In addition to the general neuroendocrine cell biomarkers INSM1, synaptophysin, and chromogranins, these tumors are typically negative for keratins and instead have highly specific biomarkers, including the GATA3 transcription factor and enzymes involved in catecholamine biosynthesis: tyrosine hydroxylase that converts L-tyrosine to L-DOPA as the rate-limiting step in catecholamine biosynthesis, dopamine beta-hydroxylase that is present in cells expressing norepinephrine, and phenylethanolamine N-methyltransferase, which converts norepinephrine to epinephrine and therefore can be used to distinguish tumors that make epinephrine. In addition to these important tools that can be used to confirm the diagnosis of a paraganglioma, new tools are recommended to determine genetic predisposition syndromes; in addition to the identification of precursor lesions, molecular immunohistochemistry can serve to identify associations with SDHx, VHL, FH, MAX, and MEN1 mutations, as well as pseudohypoxia-related pathogenesis. Paragangliomas have a well-formed network of sustentacular cells that express SOX10 and S100, but this is not a distinctive feature, as other epithelial NENs also have sustentacular cells. Indeed, it is the presence of such cells and the association with ganglion cells that led to a misinterpretation of several unusual lesions as paragangliomas; in the 2022 WHO classification, the tumor formerly known as cauda equina paraganglioma is now classified as cauda equina neuroendocrine tumor and the lesion known as gangliocytic paraganglioma has been renamed composite gangliocytoma/neuroma and neuroendocrine tumor (CoGNET). Since the 4th edition of the WHO, paragangliomas have no longer been classified as benign and malignant, as any lesion can have metastatic potential and there are no clear-cut features that can predict metastatic behavior. Moreover, some tumors are lethal without metastatic spread, by nature of local invasion involving critical structures. Nevertheless, there are features that can be used to identify more aggressive lesions; the WHO does not endorse the various scoring systems that are reviewed but also does not discourage their use. The identification of metastases is also complex, particularly in patients with germline predisposition syndromes, since multiple lesions may represent multifocal primary tumors rather than metastatic spread; the identification of paragangliomas in unusual locations such as lung or liver is not diagnostic of metastasis, since these may be primary sites. The value of sustentacular cells and Ki67 labeling as prognostic features is also discussed in this new classification. A staging system for pheochromocytoma and extra-adrenal sympathetic PGLs, introduced in the 8th Edition AJCC Cancer Staging Manual, is now included. This paper also provides a summary of the criteria for the diagnosis of a composite paragangliomas and summarizes the classification of neuroblastic tumors. This review adopts a practical question-answer framework to provide members of the multidisciplinary endocrine oncology team with a most up-to-date approach to tumors of the adrenal medulla and extra-adrenal paraganglia.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Overview of the 2022 WHO Classification of Head and Neck Neuroendocrine Neoplasms

This review article provides a brief overview of the new WHO classification by adopting a question-answer model to highlight the spectrum of head and neck neuroendocrine neoplasms which includes epithelial neuroendocrine neoplasms (neuroendocrine tumors and neuroendocrine carcinomas) arising from upper aerodigestive tract and salivary glands, and special neuroendocrine neoplasms including middle ear neuroendocrine tumors (MeNET), ectopic or invasive pituitary neuroendocrine tumors (PitNET; formerly known as pituitary adenoma) and Merkel cell carcinoma as well as non-epithelial neuroendocrine neoplasms (paragangliomas). The new WHO classification follows the IARC/WHO nomenclature framework and restricts the diagnostic term of neuroendocrine carcinoma to poorly differentiated epithelial neuroendocrine neoplasms. In this classification, well-differentiated epithelial neuroendocrine neoplasms are termed as neuroendocrine tumors (NET), and are graded as G1 NET (no necrosis and < 2 mitoses per 2 mm²; Ki67 < 20%), G2 NET (necrosis or 2-10 mitoses per 2 mm², and Ki67 < 20%) and G3 NET (> 10 mitoses per 2 mm² or Ki67 > 20%, and absence of poorly differentiated cytomorphology). Neuroendocrine carcinomas (> 10 mitoses per 2 mm², Ki67 > 20%, and often associated with a Ki67 > 55%) are further subtyped based on cytomorphological characteristics as small cell and large cell neuroendocrine carcinomas. Unlike neuroendocrine carcinomas, head and neck NETs typically show no aberrant p53 expression or loss of RB reactivity. Ectopic or invasive PitNETs are subtyped using pituitary transcription factors (PIT1, TPIT, SF1, GATA3, ER-alpha), hormones and keratins (e.g., CAM5.2). The new classification emphasizes a strict correlation of morphology and immunohistochemical findings in the accurate diagnosis of neuroendocrine neoplasms. A particular emphasis on the role of biomarkers in the confirmation of the neuroendocrine nature of a neoplasm and in the distinction of various neuroendocrine neoplasms is provided by reviewing ancillary tools that are available to pathologists in the diagnostic workup of head and neck neuroendocrine neoplasms. Furthermore, the role of molecular immunohistochemistry in the diagnostic workup of head and neck paragangliomas is discussed. The unmet needs in the field of head and neck neuroendocrine neoplasms are also discussed in this article. The new WHO classification is an important step forward to ensure accurate diagnosis that will also form the basis of ongoing research in this field.

Overview of the 2022 WHO Classification of Neuroendocrine Neoplasms

In this review, we detail the changes and the relevant features that are applied to neuroendocrine neoplasms (NENs) in the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors. Using a question-and-answer approach, we discuss the consolidation of the nomenclature that distinguishes neuronal paragangliomas from epithelial neoplasms, which are divided into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). The criteria for these distinctions based on differentiation are outlined. NETs are generally (but not always) graded as G1, G2, and G3 based on proliferation, whereas NECs are by definition high grade; the importance of Ki67 as a tool for classification and grading is emphasized. The clinical relevance of proper classification is explained, and the importance of hormonal function is examined, including eutopic and ectopic hormone production. The tools available to pathologists for accurate classification include the conventional biomarkers of neuroendocrine lineage and differentiation, INSM1, synaptophysin, chromogranins, and somatostatin receptors (SSTRs), but also include transcription factors that can identify the site of origin of a metastatic lesion of unknown primary site, as well as hormones, enzymes, and keratins that play a role in functional and structural correlation. The recognition of highly proliferative, well-differentiated NETs has resulted in the need for biomarkers that can distinguish these G3 NETs from NECs, including stains to determine expression of SSTRs and those that can indicate the unique molecular pathogenetic alterations that underlie the distinction, for example, global loss of RB and aberrant p53 in pancreatic NECs compared with loss of ATRX, DAXX, and menin in pancreatic NETs. Other differential diagnoses are discussed with recommendations for biomarkers that can assist in correct classification, including the distinctions between epithelial and non-epithelial NENs that have allowed reclassification of epithelial NETs in the spine, in the duodenum, and in the middle ear; the first two may be composite tumors with neuronal and glial elements, and as this feature is integral to the duodenal lesion, it is now classified as composite gangliocytoma/neuroma and neuroendocrine tumor (CoGNET). The many other aspects of differential diagnosis are detailed with recommendations for biomarkers that can distinguish NENs from non-neuroendocrine lesions that can mimic their morphology. The concepts of mixed neuroendocrine and non-neuroendocrine (MiNEN) and amphicrine tumors are clarified with information about how to approach such lesions in routine practice. Theranostic biomarkers that assist patient management are reviewed. Given the significant proportion of NENs that are associated with germline mutations that predispose to this disease, we explain the role of the pathologist in identifying precursor lesions and applying molecular immunohistochemistry to guide genetic testing.

Exploration of INSM1 and hASH1 as additional markers in lung cytology samples of high-grade neuroendocrine carcinoma with indeterminate neuroendocrine differentiation

BACKGROUND

Traditional neuroendocrine (NE) markers synaptophysin, chromogranin, and CD56 play an integral role in affirming the diagnosis of high-grade lung NE carcinoma, however promising markers, INSM1, and hASH1, have been identified. We investigated the utility of these markers in pulmonary cytology specimens, particularly in cases where results of traditional NE markers were equivocal.

METHODS

A retrospective search of cytology cases obtained via endobronchial ultrasound (EBUS)-guided FNA revealed 26 cases of high-grade lung carcinoma where an indeterminate diagnosis of small-cell lung carcinoma (SCLC) was based on equivocal IHC staining with traditional NE markers. A separate cohort of 23 cases positive for all traditional markers with a definitive diagnosis of SCLC was also selected. Cytology cellblock sections were immunostained with INSM1 and hASH1 and analyzed using H-score methodology (score range 0-300). A score of ≥95 was considered "positive."

RESULTS

INSM1 was positive in 19/24 (79.2%) of cases of high-grade lung carcinoma with indeterminate NE differentiation, while hASH1 was positive in 6/24 (25.0%). Chromogranin was seen only focally positive (<10% of cells) in 4/24 (16.7%), synaptophysin positive in 16/24 (66.7%), and CD56 positive in 14/21 (66.7%). Among unambiguous cases, INSM1 was positive in all cases with an average score of 233.9, while hASH1 was positive in 21/23 (91.3%) with an average score of 196.3.

CONCLUSION

Compared with traditional NE stains and to hASH1, INSM1 was expressed in a higher number of cases of high-grade lung NE carcinomas in cytology cellblock specimens, making it a superior, more sensitive NE marker.

The Expression of Chromogranin A, Syanptophysin and Ki67 in Detecting Neuroendocrine Neoplasma at High Grade Colorectal Adenocarcinoma

BACKGROUND: Neuroendocrine neoplasm (NEN) is an epithelial cell neoplasm that can give a histopathological appearance resembling high-grade colorectal adenocarcinoma. Immunohistochemical assays with specific neuroendocrine markers of chromogranin A and synaptophysin are required to establish a definite diagnosis of NEN. AIM: This study aimed to determine whether there was an expression of chromogranin A, synaptophysin and Ki67 which indicated the presence of neuroendocrine neoplasms in samples that have been diagnosed as high-grade colorectal adenocarcinoma. MATERIALS AND METHODS: A study of the expression of chromogranin A, synaptophysin and Ki67 in paraffin blocks was carried out as a result of biopsy and tissue surgery of 70 samples of colorectal tumor specimens diagnosed with colorectal adenocarcinoma. Descriptive analyses were used to assess the study results of the amount of chromogranin A, synaptophysin, and sample characteristics. RESULTS: We discovered that eight (8) samples (11.4%) were NEN from 70 previously diagnosed samples as high-grade colorectal adenocarcinoma using immunohistochemical assay with neuroendocrine markers, namely chromogranin A and synaptophysin. CONCLUSION: The final diagnosis obtained from 8 samples diagnosed as NEN were Neuroendocrine tumor (NET) G1, G2, and G3, respectively 1.4% and LCNEC 7.1% based on the specific neuroendocrine markers of chromogranin A, synaptophysin and Ki67.

Significance of chromogranin A and synaptophysin in medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare thyroid carcinoma of C-cell deviation that produces and secretes calcitonin (CT) and chromogranin A (CgA) into the blood. Thus, CT and CgA are immunohistochemical and serum markers for MTCs. MTC occurs in sporadic and inheritable forms. The hallmark of inheritable cases in multiple endocrine neoplasm 2 (MEN2) is MTC. MEN2 cases represent 30% through germline RET proto-oncogene mutation and occur in younger ages involving bilateral thyroid lobes. Sporadic cases are 70% and occur in older ages. CgA and synaptophysin (SPY) are the two most widely used and reliable immunohistochemical markers for neuroendocrine tumors, including MTCs. This study aimed to detect different immunohistochemical staining patterns for CgA and SPY between non-symptomatic small lesions and invading larger aggressive tumors in both MEA2 cases and sporadic cases. There was different CgA and SPY immunostaining in MEA2 cases where small tumors (≤0.3 cm) were lesser immunostained for CgA and SPY, despite intense staining for CT, compared to the larger (≥0.5 cm) tumors, stronger immunostained for CgA. There was also different CgA and SPY immunohistochemical staining in sporadic cases between small lesions (≤0.5 cm) and larger tumors (≥1.0 cm). One small sporadic tumor (0.5 cm × 0.3 cm) was strongly and weakly, patchy stained for CgA and SPY, respectively, while larger sporadic tumors were diffusely and strongly stained for CgA and SPY. Therefore, stronger CgA and SPY immunostaining for larger tumors in both MEA2 and sporadic cases may be used as independent, aggressive immunohistochemical markers for MTCs.

Pheochromocytoma presenting as a pancreatic mass: Avoiding a dangerous pitfall in endoscopic ultrasound-guided fine needle aspiration biopsy using GATA3 immunostain

Pheochromocytomas and sympathetic paragangliomas are rare tumours arising from chromaffin cells, producing catecholamines in various amounts. Fatal hypertensive episodes may occur perioperatively, which are preventable by alpha adrenergic receptor blockers. The perioperative mortality rate of diagnosed versus undiagnosed catecholamine-producing tumours is significant, considering that only a minority of tumours develop metastasis. Herein we describe a case of a primary adrenal pheochromocytoma referred to as a pancreatic tumour, successfully diagnosed by endoscopic ultrasound-guided fine needle aspiration biopsy, with a distinct morphology (prominent nuclear anisonucleosis, intranuclear pseudoinclusions, and multinucleation) and immunohistochemical signature.

Monoclonal/polyclonal PAX-8, PTH and GATA3 immunohistochemistry in parathyroid lesions

BACKGROUND

Parathyroid gland (PG) is an endocrine organ which may display different immunohistochemical stainings with chief cells and oxyphilic cells in normal as well as hyperplasic/tumoral lesions.

PURPOSE

In this study, we aimed to identify the demographic properties and diagnostic value of the GATA3 antibody, which is a transcription factor in addition to PTH, and of PAX-8 (monoclonal and polyclonal) antibody.

METHODS

We have analyzed in detail the cellular components and staining intensities of 46 adenomas all of which contained parathyroid rims, 12 hyperplasia and 5 adjacent non-neoplastic thyroidectomy materials (63 patients, 114 tissues).

RESULTS

While no staining was identified in the thyroid tissue, cytoplasmic PTH immunoreactivity was observed in all (100%) normal parathyroid tissues, rim of PGs and hyperplasia, and in 43/46 cases (93.4%) of adenomas. Adenoma and hyperplasia were less stained than normal PG (p < 0.05). We detected GATA3 staining in all cases except for the thyroid (100%). Weak positivity (1+) was most apparent in adenoma cases (p < 0.05). Monoclonal PAX-8 immunoreactivity was not identified in any normal parathyroid tissue and rim of PG but positive immunoreactivity was detected in 83.3% of hyperplasia cases (10/12), 84.8% of adenoma (39/46) and 100% of thyroid tissues (5/5) (p < 0.05). However, polyclonal PAX-8 immunoreactivity was detected in one normal parathyroid tissue (1/5) and seven (7/46) rim of PGs. In cases of hyperplasia and adenoma, positive immunoreactivity was 75% (9/12) and 74% (34/46), respectively.

CONCLUSION

In conclusion, we have observed that PTH and GATA3 constitute a much more reliable and sensitive marker for parathyroid and are stained less in adenomas. While monoclonal PAX-8 (MRQ-50) never stains normal parathyroid and rim of PGs, it may help in the differential diagnosis of proliferated parathyroid lesions as a considerably sensitive and relatively specific marker by staining hyperplasic parathyroid, adenomas and the thyroid.

Neuroendocrine Tumors of the Thyroid and Their Mimics

This paper will review neuroendocrine lesions of the thyroid and the differential diagnosis with the most significant such tumor of the thyroid, that is, medullary thyroid carcinoma. A brief overview of the understanding of this tumor's identification as a lesion of C cells and its familial and syndromic associations will be presented. Then, a discussion of the various mimics of medullary carcinoma will be given with an approach to the types of tests that can be done to arrive at a correct diagnostic conclusion. This review will focus on practical "tips" for the practicing pathologist.

Cytokeratin 8/18-negative somatotroph pituitary neuroendocrine tumours (PitNETs, adenomas) show variable morphological features and do not represent a clinicopathologically distinct entity

AIMS

In somatotroph pituitary neuroendocrine tumours (adenomas), a pattern of cytokeratin (CK) 18 expression is used for tumour subclassification, with possible clinical implications. Rare somatotroph tumours do not express CK 18. We aimed to characterise this subset clinically and histologically.

METHODS AND RESULTS

Clinical and pathological data for the study were derived from a previously published data set of a cohort of 110 patients with acromegaly. Data included serum levels of insulin-like growth factor 1 (IGF1), growth hormone (GH), prolactin and thyroid-stimulating hormone (TSH), tumour diameter, tumour invasion defined by Knosp grade and immunohistochemical data concerning the expression of Ki67, p53, E-cadherin, somatostatin receptor (SSTR)1, SSTR2A, SSTR3, SSTR5 and D2 dopamine receptor. Additional immunohistochemical analysis (AE1/3, CK 8/18, vimentin, neurofilament light chain, internexin-α) was performed. CK 18 was negative in 10 of 110 (9.1%) tumours. One of these tumours was immunoreactive with CK 8/18 antibody, while the remainder expressed only internexin-α intermediate filament in patterns similar to CK 18 (perinuclear fibrous bodies). CK-negative tumours showed no significant differences with respect to biochemical, radiological or pathological features. They showed significantly higher expression of SSTR2A compared to the sparsely granulated subtype and significantly lower expression of E-cadherin compared to the non-sparsely granulated subtypes of tumours. The tumours showed divergent morphology and hormonal expression: two corresponded to densely granulated tumours and three showed co-expression of prolactin and morphology of either mammosomatotroph or somatotroph-lactotroph tumours. Four tumours showed morphology and immunoprofile compatible with plurihormonal Pit1-positive tumours.

CONCLUSIONS

CK-negative somatotroph tumours do not represent a distinct subtype of somatotroph tumours, and can be further subdivided according to their morphology and immunoprofile.

Survival outcomes and prognostic factors of primary small cell carcinoma of the esophagus

Background

Primary small cell carcinoma of the esophagus (PSCCE) is a rare and aggressive malignancy. It has a poor survival rate, and there is no consensus as to a standard therapeutic modality. In this study, we aimed to investigate the prognostic factors and evaluate the outcomes of patients with PSCCE who had been treated with different therapeutic methods.

Methods

We retrospectively evaluated 113 consecutive patients with PSCCE who received treatment at our center from 2003 to 2016. The primary endpoint was overall survival (OS). The Cox regression model was used to analyze the prognostic factors. The survival analysis was calculated using the Kaplan-Meier and log-rank methods.

Results

The 12- and 36-month OS rates of all 113 enrolled patients were 45% and 12%, respectively. A significantly prolonged OS rate was associated with lymph node stages N0–N1 (P=0.022), the Veterans’ Administration Lung Study Group (VALSG) system limited-disease (LD) staging (P=0.040), and multimodality treatments (P=0.047). Patients with regional lymph node metastasis benefited more from surgery combined with chemotherapy than surgery or chemotherapy alone (P=0.046). Concerning chemotherapy, cisplatin plus etoposide was the regimen most commonly used to treat PSCCE patients (67.5%).

Conclusions

An early lymph node stage, the VALSG LD staging, and multimodality treatments were identified as independent prognostic factors of PSCCE. Surgery combined with adjuvant chemotherapy was especially necessary for LD stage PSCCE patients with lymph node stages N1–3.

Molecular Pathology of Well-Differentiated Pulmonary and Thymic Neuroendocrine Tumors: What Do Pathologists Need to Know?

Thoracic (pulmonary and thymic) neuroendocrine tumors are well-differentiated epithelial neuroendocrine neoplasms that are classified into typical and atypical carcinoid tumors based on mitotic index cut offs and presence or absence of necrosis. This classification scheme is of great prognostic value but designed for surgical specimens, only. Deep molecular characterization of thoracic neuroendocrine tumors highlighted their difference with neuroendocrine carcinomas. Neuroendocrine tumors of the lung are characterized by a low mutational burden, and a high prevalence of mutations in chromatin remodeling and histone modification-related genes, whereas mutations in genes frequently altered in neuroendocrine carcinomas are rare. Molecular profiling divided thymic neuroendocrine tumors into three clusters with distinct clinical outcomes and characterized by a different average of copy number instability. Moreover, integrated histopathological, molecular and clinical evidence supports the existence of a grey zone category between neuroendocrine tumors (carcinoid tumors) and neuroendocrine carcinomas. Indeed, cases with well differentiated morphology but mitotic/Ki-67 indexes close to neuroendocrine carcinomas have been increasingly recognized. These are characterized by specific molecular profiles and have an aggressive clinical behavior. Finally, thoracic neuroendocrine tumors may arise in the background of genetic susceptibility, being MEN1 syndrome the well-defined familial form. However, pathologists should be aware of rarer germline variants that are associated with the concurrence of neuroendocrine tumors of the lung or their precursors (such as DIPNECH) with other neoplasms, including but not limited to breast carcinomas. Therefore, genetic counseling for all young patients with thoracic neuroendocrine neoplasia and/or any patient with pathological evidence of neuroendocrine cell hyperplasia-to-neoplasia progression sequence or multifocal disease should be considered.

Complete remission of Cdx-2 positive primary testicular carcinoid tumor: 10-years follow-up and literature review

BACKGROUND

The neuroendocrine cells can cause a variety of malignancies throughout the human body known as the neuroendocrine tumors (NETs) or carcinoid tumors. The primary testicular carcinoid tumor (PTCT) accounts for less than 1% of the testicular neoplasms and for only 0.2% of all carcinoid tumors representing already a very rare neoplastic entity. Here, we present a patient with a history of an exceptionally rare primary testicular carcinoid tumor, staining positive for Cdx-2 along with a literature review.

CASE PRESENTATION

A 44-year old patient without significant past medical history was diagnosed in September 2009 with primary testicular carcinoid tumor, which was surprisingly staining positively for Cdx-2, too. At the time of the initial diagnosis the tumor was already showing histopathological infiltration of veins. DOTA-TATE-PET/CT imaging and endoscopy studies did not show any signs of distant metastases and in particular no gastrointestinal manifestation following no further medical indication for systemic chemotherapy. The continuous and close follow-up of the patient has reached a total of over 10 years at the time of publication remaining in complete remission.

CONCLUSION

The diagnosis of primary testicular carcinoid is based on histopathology. The detailed histopathologic assessment of biomarkers based on immunohistochemistry is very important for the classification and the prognosis of the primary testicular carcinoid tumor. Primary testicular carcinoid tumor with Cdx-2 positive stain outlines an exceptionally rare neoplastic entity without a consensus about general follow-up guidelines, requiring close clinical and imaging aftercare and consideration in Cdx-2 positive metastatic tumor of unknown origin.

[Neuroendocrine markers in parathyroid tumors]

The parathyroid glands (PTGs) are a key regulator of calcium and phosphorus metabolism in the human body. In terms of their, morphological and immunophenotypic characteristics, PTGs are neuroendocrine organs, and their neoplasms are neuroendocrine tumors. These neoplasms include adenoma and cancer; in addition, glandular hyperplasia may develop, which is most characteristic of multiple endocrine neoplasia (MEN1, MEN2a, and MEN4) syndromes. The morphological characteristics of pathologically altered PTGs in MEN syndromes are variable. The analysis and generalization of knowledge about the features and expression of various immunohistochemical markers in PTG tissue in health and in diseases are useful in the practical work of not only pathologists, but also clinicians of various specialties.

Caracterización de pacientes con tumores neuroendocrinos en un hospital de referencia de alta complejidad

Introducción. Los tumores neuroendocrinos comprenden una amplia familia tumoral, siendo de mayor frecuencia aquellos localizados en el tracto gastrointestinal, los pulmones, el timo y el páncreas. Ocurren con poca frecuencia y cursan con un comportamiento biológico variable. El objetivo del presente estudio fue describir las características demográficas y clínicas de los pacientes con esta entidad en un hospital de alta complejidad. Métodos. Estudio descriptivo con revisión de historias clínicas correspondientes a pacientes con tumor neuroendocrino, cuya muestra histológica fue analizada en el Departamento de Patología del Hospital Pablo Tobón Uribe, Medellín, Colombia, entre 2010 y 2015. Se describen frecuencias de localización, grado de diferenciación y perfil de inmuno-histoquímica. Resultados. Se revisaron 111 historias, de las que el 51,5 % correspondió a pacientes masculinos, con una mediana de edad al momento del diagnóstico de 48 años. Las comorbilidades más frecuentes fueron: hipertensión arterial (38,6 %), hipotiroidismo (15,8 %) y diabetes mellitus (11,9 %). El antecedente de neoplasia estuvo presente en el 13,9 % de los casos. Un 59,4 % de las muestras correspondieron a tumores primarios, el 34,8 % estaban localizados en el páncreas. El hígado fue el órgano más comprometido por metástasis (73,3 %). De los tumores neuroendocrinos, el 27 % correspondió a tumores grado 1 del tracto gastrointestinal o del páncreas, el 36 % a grado 2 y el 27,9 % a grado 3. El 3,6 % correspondió a tumores pulmonares de grado bajo o intermedio y el 5,4 % a tumores pulmonares de alto grado. Los marcadores tumorales con mayor positividad fueron sinaptofisina (97,2 %), citoqueratinas AE1/AE3 (95 %), CD56 (91,3%) y cromogranina (87,8%). Discusión. Los tumores neuroendocrinos tienen características clínicas e histopatológicas diversas. Conocer las características de los pacientes afectados permite una aproximación de la epidemiología local aplicable a futuras investigaciones.  

Pituitary Gangliocytoma Producing TSH and TRH: A Review of "Gangliocytomas of the Sellar Region"

PURPOSE

Pituitary gangliocytomas (GCs) are rare neuronal tumors that present with endocrinological disorders, such as acromegaly, amenorrhea-galactorrhea syndrome, and Cushing's disease. Most pituitary GCs coexist with pituitary adenomas pathologically and are diagnosed as mixed gangliocytoma-adenomas. Herein, we report a case of 45-year-old man who presented with the syndrome of inappropriate secretion of thyroid-stimulating hormone (SITSH) and discuss the pathogenesis of pituitary GCs.

METHODS

Pituitary magnetic resonance imaging showed an 8-mm homogeneous and poorly enhanced mass inside the pituitary gland. Endoscopic transsphenoidal surgery was performed under a preoperative diagnosis of thyrotroph adenoma. However, the tumor was finally diagnosed as gangliocytoma without an adenomatous component. The tumor was further analyzed via immunohistochemistry and electron microscopy. Additionally, we searched MEDLINE and PubMed for previously published cases of isolated pituitary GCs and analyzed the reported clinicopathological findings.

RESULTS

The patient showed complete clinical and endocrinological recovery after an operation. The tumor was positive for thyrotropin (TSH), TSH-releasing hormone (TRH), Pit-1, GATA-2, and most neuronal markers. Electron microscopy demonstrated the presence of intracytoplasmic secretory granules and neuronal processes. Co-secreting hypothalamic and pituitary hormone inside the tumor indicated autocrine/paracrine endocrinological stimulation.

CONCLUSION

Herein, we report a case of SITSH caused by an isolated pituitary gangliocytoma, expressing both TSH and TRH, which, to our best knowledge, is the first reported case of such a condition. The multidirectional differentiation and multihormonal endocrine characteristics of these tumors indicate that they are a member of neuroendocrine neoplasms, further supporting that they are derived from neural crest cells.

Clinical implications of mismatch repair deficiency screening in patients with mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN)

INTRODUCTION

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN) are rare tumors, mainly encountered in the gastroenteropancreatic tract. Based on the limited available data, MiNEN is usually a highly aggressive neoplasm combining a high-grade neuroendocrine and a non-neuroendocrine component, associated with a poor prognostic outlook. Deficient DNA mismatch repair (MMR) results in microsatellite instability, which is a useful screening marker for identifying patients with Lynch syndrome and a prognostic factor for chemotherapeutic interventions. Little information on MMR status in MiNEN is available in published studies. Therefore, the purpose of this study was to explore the status and putative role of MMR on MiNEN.

METHODS

We investigated the MMR status in 44 cases and characterized their clinicopathological features and prognoses. Immunohistochemistry was performed for four mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2).

RESULTS

Mean age at diagnosis was 61 years, and 75% of the patients were male. Lymph node metastases were observed in 14 (35.9%) patients. The most common tumor localizations were gastric (28 patients, 63.6%). Lack of immunohistochemical expression of MMR proteins was shown in 38.6% of cases. The common deletion rates of one or more proteins were 29.4% (5/17) for MLH1/PMS2 and 23.5% (4/17) for MLH1. Correlation between clinicopathological parameters showed that MMR deficiency was significantly associated with early TNM stage and better prognoses in patients with MiNEN.

CONCLUSION

MiNENs showed frequent losses of MMR protein expression, which contributes to the knowledge of the pathological and clinical aspects of MiNEN tumors.

Characterizing and classifying neuroendocrine neoplasms through microRNA sequencing and data mining

Neuroendocrine neoplasms (NENs) are clinically diverse and incompletely characterized cancers that are challenging to classify. MicroRNAs (miRNAs) are small regulatory RNAs that can be used to classify cancers. Recently, a morphology-based classification framework for evaluating NENs from different anatomical sites was proposed by experts, with the requirement of improved molecular data integration. Here, we compiled 378 miRNA expression profiles to examine NEN classification through comprehensive miRNA profiling and data mining. Following data preprocessing, our final study cohort included 221 NEN and 114 non-NEN samples, representing 15 NEN pathological types and 5 site-matched non-NEN control groups. Unsupervised hierarchical clustering of miRNA expression profiles clearly separated NENs from non-NENs. Comparative analyses showed that miR-375 and miR-7 expression is substantially higher in NEN cases than non-NEN controls. Correlation analyses showed that NENs from diverse anatomical sites have convergent miRNA expression programs, likely reflecting morphological and functional similarities. Using machine learning approaches, we identified 17 miRNAs to discriminate 15 NEN pathological types and subsequently constructed a multilayer classifier, correctly identifying 217 (98%) of 221 samples and overturning one histological diagnosis. Through our research, we have identified common and type-specific miRNA tissue markers and constructed an accurate miRNA-based classifier, advancing our understanding of NEN diversity.

Data set for the reporting of pheochromocytoma and paraganglioma: explanations and recommendations of the guidelines from the International Collaboration on Cancer Reporting

BACKGROUND AND OBJECTIVES

The International Collaboration on Cancer Reporting (ICCR) is a not-for-profit to develop evidence-based, internationally agreed-upon standardized data sets for each anatomic site, to be used throughout the world. Providing global standardization of pathology tumor classification, staging, and other reporting elements will lead to improved patient management and enhanced epidemiological research.

METHODS

Pheochromocytoma and paraganglioma are uncommon and are frequently overlooked in registry data sets. Malignant criteria have previously been defined only when there was metastatic disease.

RESULTS

With recent recognition of a significant inheritance association and the development of risk stratification tools, this data set was created in order to obtain more meaningful outcomes and management data, using similar criteria across the global pathology community. Issues related to key core and non-core elements, especially clinical hormonal status, familial history, tumor focality, proliferative fraction, adverse or risk stratification features, and ancillary techniques, are discussed in the context of daily application to these types of specimens.

CONCLUSIONS

The ICCR data set, developed by an international panel of endocrine organ specialists, establishes a pathology-standardized reporting guide for pheochromocytoma and paraganglioma.

Do You Know the Details of Your PAX8 Antibody? Monoclonal PAX8 (MRQ-50) Is Not Expressed in a Series of 45 Medullary Thyroid Carcinomas

Medullary thyroid carcinomas display cytologic and architectural features that can simulate various primary and metastatic neoplasms. PAX8 immunoexpression in neuroendocrine neoplasms yielded antibody-dependent findings. Since the data regarding the expression profile of monoclonal PAX8 (MRQ-50) antibody is limited in large series of medullary thyroid carcinomas, this study investigated the expression profile of PAX8 (MRQ-50) in a series of 45 medullary thyroid carcinomas. PAX8 (MRQ-50) expression was noted in the thyroid follicular epithelial cells surrounding the tumor and was negative in all medullary thyroid carcinomas. In addition, twenty medullary thyroid carcinomas showed scattered entrapped thyroid follicular epithelial cells at the periphery of the tumor. Entrapped follicular epithelial cells were positive for PAX8 and thyroglobulin, and were negative for monoclonal CEA and calcitonin. A panel approach combining monoclonal antibodies to transcription factors, hormones and cell-specific peptides often assist diagnosticians in the workup of the cellular origin of a neuroendocrine neoplasm. Since PAX8 immunostaining is dependent on the antibody characteristics in neuroendocrine neoplasms, pathologists should be aware of the details of the PAX8 antibody used in a particular case.

Dedifferentiation of neuroendocrine carcinoma of the uterine cervix in hypoxia

Neuroendocrine carcinoma of small cell type (SCNEC) is a rare pathological subtype in cervical cancer, which has a worse prognosis than other histological cell types. Due to its low incidence and the lack of experimental platforms, the molecular characteristics of SCNEC in the cervix remain largely unknown. Using the cancer tissue-originated spheroid (CTOS) method-an ex vivo 3D culture system that preserves the differentiation status of the original tumors-we established a panel of CTOS lines of SCNEC. We demonstrated that xenograft tumors and CTOSs, respectively, exhibited substantial intra-tumor and intra-CTOS variation in the expression levels of chromogranin A (CHGA), a neuroendocrine tumor marker. Since hypoxia affects differentiation in various tumors and in stem cells, we also investigated how hypoxia affected neuroendocrine differentiation of SCNEC of the uterine cervix. In the CTOS line cerv21, hypoxia suppressed expression of the neuroendocrine markers CHGA and synaptophysin (SYP). Flow cytometry analysis using CD99 (a membrane protein marker of SCNEC) revealed decreased CD99 expression in a subset of cells under hypoxic conditions. These expression changes were attenuated by HIF-1α knockdown, and by a Notch inhibitor, suggesting that these molecules played a role in the regulation of neuroendocrine differentiation. The examined SCNEC markers were suppressed under hypoxia in multiple CTOS lines. Overall, our present results indicated that neuroendocrine differentiation in SCNEC of the uterus is a variable phenotype, and that hypoxia may be one of the factors regulating the differentiation status.

Primary malignant ovarian carcinoid; management and outcomes

OBJECTIVE

To investigate the clinicopathological characteristics and survival of patients with malignant ovarian carcinoid tumor (OC).

MATERIALS AND METHODS

The National Cancer Database was accessed and patients diagnosed between 2004 and 2015 with a OC who did not have a personal history of a tumor at another site were selected. Overall survival (OS) was assessed for patients who had ≥1 month of follow-up. OS rates were estimated following generation of Kaplan-Meier curves and compared with the log-rank test.

RESULTS

A total of 588 patients with a median age of 51.5 years were identified. The majority were White (71.6%), had unilateral tumors (94.2%) with a median size of 3.8 cm that were confined to the ovary (88%). Patients with early stage disease (n = 431) had excellent OS compared to those with advanced stage (II-IV) disease (n = 51), p < 0.001; 5-yr OS rates were 95.4% and 53.1% respectively. For patients with stage I disease, there was no difference in OS between those who did (n = 211) and did not (n = 175) have hysterectomy, p = 0.92. For patients with advanced stage disease, administration of adjuvant chemotherapy was not associated with better survival, p = 0.093.

CONCLUSIONS

OCs are typically small, unilateral tumors confined to the ovary arising in perimenopausal patients. Survival outcomes are excellent for patients with early stage disease and unilateral salpingo-oophorectomy appears to be curative.

Carotid Body Paraganglioma with Prominent Lymphocytic Infiltration Mimicking Metastatic Lymph Node: A Case Report

Carotid body paraganglioma is a neuroendocrine neoplasm of the mandibular region. Due to its prominent stromal alternations, carotid body paraganglioma is a great emulator of other neoplasms in the head and neck region especially in metastatic tumors and its definite diagnosis is a great challenge. To the best of our knowledge, the most frequently reported variant is sclerosing and paraganglioma with a prominent lymphoplasmacytic infiltration is extremely rare. We report a rare case of a carotid body lymphoplasmacytic paraganglioma presented as a single asymptomatic mass of the right mandibular region in a 45-year-old woman. In order to exclude other possibilities, the use of immunohistochemistry is essential which shows a strong positive immunoreaction for chromogranin and synaptophysin. Surgical resection is the treatment of choice which is replaced with radiotherapy in contraindications. Overall, the tumor has a favorable clinical outcome.

Thyroid Tumors You Don't Want to Miss

This article examines more uncommon thyroid entities, including anaplastic thyroid carcinoma, poorly differentiated thyroid carcinoma, rare papillary thyroid carcinoma variants, medullary thyroid carcinoma, non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), and multiple adenomatous nodules in the setting of Cowden syndrome. These entities were chosen based on their clinical significance and because they can be diagnostically challenging due to their morphologic diversity and overlap with other thyroid tumors. This article addresses the diagnostic features of each entity, focusing on how to avoid potential pitfalls and mimics while also highlighting the clinical implications of each diagnosis.

Neuroendocrine Tumors of the Lung: Updates and Diagnostic Pitfalls

Neuroendocrine tumors of the lung constitute approximately 20% of all primary lung tumors and include typical carcinoid, atypical carcinoid, small cell carcinoma, and large cell neuroendocrine carcinoma. Given their morphologic overlap with diverse mimics, neuroendocrine tumors of the lung can be diagnostically challenging. This review discusses the clinical, histologic, immunophenotypic, and molecular features of pulmonary neuroendocrine tumors, along with common diagnostic pitfalls and strategies for avoidance.

Uniform and Robust Nuclear Expression of HES1 in Neuroendocrine Neoplasms

Introduction. Neuroendocrine neoplasms (NENs) are neoplasms that most commonly arise from gastrointestinal tract, pancreas, and lung. HES1 is a downstream target of Notch signaling pathway. The current literature about HES1 expression in NENs is sparse and inconsistent. Methods. In this study, we evaluated HES1 expression by immunohistochemistry in a total of 32 cases of NENs, including 13 well-differentiated neuroendocrine tumors from gastrointestinal tract, 10 cases of well-differentiated neuroendocrine tumors of pancreas, 9 cases from lung, including 4 cases of typical carcinoid, 1 case of atypical carcinoid, and 4 cases of neuroendocrine carcinoma. The intensity of the stain was scored from - to +++, and the distribution of the staining of HES1 was evaluated. Results. HES1 demonstrates uniform robust (+++) nuclear staining pattern in the tumor cells of all the NENs (32/32), regardless of the origin of the system and the grade of the tumor. Conclusions. HES1 is uniformly expressed in NENs with robust nuclear expression pattern. Our finding suggests that NOTCH1 or HES1 inhibitor is a potential therapeutic choice for neuroendocrine neoplasms.