A novel splicing site IRP1 somatic mutation in a patient with pheochromocytoma and JAK2V617F positive polycythemia vera: a case report

The Molecular Classification of Pheochromocytomas and Paragangliomas: Discovering the Genomic and Immune Landscape of Metastatic Disease

Pheochromocytomas (PCCs) and paragangliomas (PGLs, together PPGLs) are the most hereditary tumors known. PPGLs were considered benign, but the fourth edition of the World Health Organisation (WHO) classification redefined all PPGLs as malignant neoplasms with variable metastatic potential. The metastatic rate differs based on histopathology, genetic background, size, and location of the tumor. The challenge in predicting metastatic disease lies in the absence of a clear genotype-phenotype correlation among the more than 20 identified genetic driver variants. Recent advances in molecular clustering based on underlying genetic alterations have paved the way for improved cluster-specific personalized treatments. However, despite some clusters demonstrating a higher propensity for metastatic disease, cluster-specific therapies have not yet been widely adopted in clinical practice. Comprehensive genomic profiling and transcriptomic analyses of large PPGL cohorts have identified potential new biomarkers that may influence metastatic potential. It appears that no single biomarker alone can reliably predict metastatic risk; instead, a combination of these biomarkers may be necessary to develop an effective prediction model for metastatic disease. This review evaluates current guidelines and recent genomic and transcriptomic findings, with the aim of accurately identifying novel biomarkers that could contribute to a predictive model for mPPGLs, thereby enhancing patient care and outcomes.

Iron deficiency and supplementation in heart failure

Non-anaemic iron deficiency (NAID) is a strategic target in cardiovascular medicine because of its association with a range of adverse effects in various conditions. Endeavours to tackle NAID in heart failure have yielded mixed results, exposing knowledge gaps in how best to define 'iron deficiency' and the handling of iron therapies by the body. To address these gaps, we harness the latest understanding of the mechanisms of iron homeostasis outside the erythron and integrate clinical and preclinical lines of evidence. The emerging picture is that current definitions of iron deficiency do not assimilate the multiple influences at play in patients with heart failure and, consequently, fail to identify those with a truly unmet need for iron. Additionally, current iron supplementation therapies benefit only certain patients with heart failure, reflecting differences in the nature of the unmet need for iron and the modifying effects of anaemia and inflammation on the handling of iron therapies by the body. Building on these insights, we identify untapped opportunities in the management of NAID, including the refinement of current approaches and the development of novel strategies. Lessons learned from NAID in cardiovascular disease could ultimately translate into benefits for patients with other chronic conditions such as chronic kidney disease, chronic obstructive pulmonary disease and cancer.

Polycythemia Secondary to Renal Hemangioblastoma: A Case Report and Literature Review

Secondary polycythemia is a paraneoplastic syndrome observed in tumors with excessive erythropoietin (EPO) production. Renal cell carcinoma (RCC) and cerebellar hemangioblastoma are the 2 most well-known tumors to induce secondary polycythemia. Hemangioblastomas occurring in the kidney are rare. In this work we present a case of renal hemangioblastoma that caused erythrocytosis in a 19-year-old man. We demonstrated intratumoural EPO production by immunohistochemistry, and conducted whole-exome sequencing to evaluate possible genetic alterations that reported to induce tumor-related polycythemia. In spite of an indolent clinical behavior, renal hemangioblastoma is difficult to differentiate from RCC not only clinically, but also histopathologically. Given that RCC is the most well-known renal tumor to induce erythrocytosis, the uncommon manifestation of polycythemia in renal hemangioblastoma, as shown in our case, can cause further diagnostic challenges. Renal hemangioblastoma should be listed in the differential diagnoses of renal tumors presenting with erythrocytosis, apart from the most common RCC.

Iron Mining for Erythropoiesis

Iron is necessary for essential processes in every cell of the body, but the erythropoietic compartment is a privileged iron consumer. In fact, as a necessary component of hemoglobin and myoglobin, iron assures oxygen distribution; therefore, a considerable amount of iron is required daily for hemoglobin synthesis and erythroid cell proliferation. Therefore, a tight link exists between iron metabolism and erythropoiesis. The liver-derived hormone hepcidin, which controls iron homeostasis via its interaction with the iron exporter ferroportin, coordinates erythropoietic activity and iron homeostasis. When erythropoiesis is enhanced, iron availability to the erythron is mainly ensured by inhibiting hepcidin expression, thereby increasing ferroportin-mediated iron export from both duodenal absorptive cells and reticuloendothelial cells that process old and/or damaged red blood cells. Erythroferrone, a factor produced and secreted by erythroid precursors in response to erythropoietin, has been identified and characterized as a suppressor of hepcidin synthesis to allow iron mobilization and facilitate erythropoiesis.

Personalized Management of Pheochromocytoma and Paraganglioma

Pheochromocytomas/paragangliomas are characterized by a unique molecular landscape that allows their assignment to clusters based on underlying genetic alterations. With around 30% to 35% of Caucasian patients (a lower percentage in the Chinese population) showing germline mutations in susceptibility genes, pheochromocytomas/paragangliomas have the highest rate of heritability among all tumors. A further 35% to 40% of Caucasian patients (a higher percentage in the Chinese population) are affected by somatic driver mutations. Thus, around 70% of all patients with pheochromocytoma/paraganglioma can be assigned to 1 of 3 main molecular clusters with different phenotypes and clinical behavior. Krebs cycle/VHL/EPAS1-related cluster 1 tumors tend to a noradrenergic biochemical phenotype and require very close follow-up due to the risk of metastasis and recurrence. In contrast, kinase signaling-related cluster 2 tumors are characterized by an adrenergic phenotype and episodic symptoms, with generally a less aggressive course. The clinical correlates of patients with Wnt signaling-related cluster 3 tumors are currently poorly described, but aggressive behavior seems likely. In this review, we explore and explain why cluster-specific (personalized) management of pheochromocytoma/paraganglioma is essential to ascertain clinical behavior and prognosis, guide individual diagnostic procedures (biochemical interpretation, choice of the most sensitive imaging modalities), and provide personalized management and follow-up. Although cluster-specific therapy of inoperable/metastatic disease has not yet entered routine clinical practice, we suggest that informed personalized genetic-driven treatment should be implemented as a logical next step. This review amalgamates published guidelines and expert views within each cluster for a coherent individualized patient management plan.

New Insights on the Genetics of Pheochromocytoma and Paraganglioma and Its Clinical Implications

Simple Summary

Pheochromocytoma and paraganglioma (together PPGL) are rare neuroendocrine tumors that arise from chromaffin tissue and produce catecholamines. Approximately 40% of cases of PPGL carry a germline mutation, suggesting that they have a high degree of heritability. The underlying mutation influences the PPGL clinical presentation such as cell differentiation, specific catecholamine production, tumor location, malignant potential and genetic anticipation, which helps to better understand the clinical course and tailor treatment accordingly. Genetic testing for pheochromocytoma and paraganglioma allows an early detection of hereditary syndromes and facilitates a close follow-up of high-risk patients. In this review article, we present the most recent advances in the field of genetics and we discuss the latest guidelines on the surveillance of asymptomatic SDHx mutation carriers.

Abstract

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) are rare neuroendocrine tumors that arise from chromaffin cells. PHEOs arise from the adrenal medulla, whereas PGLs arise from the neural crest localized outside the adrenal gland. Approximately 40% of all cases of PPGLs (pheochromocytomas/paragangliomas) are associated with germline mutations and 30–40% display somatic driver mutations. The mutations associated with PPGLs can be classified into three groups. The pseudohypoxic group or cluster I includes the following genes: SDHA, SDHB, SDHC, SDHD, SDHAF2, FH, VHL, IDH1/2, MHD2, EGLN1/2 and HIF2/EPAS; the kinase group or cluster II includes RET, NF1, TMEM127, MAX and HRAS; and the Wnt signaling group or cluster III includes CSDE1 and MAML3. Underlying mutations can help understand the clinical presentation, overall prognosis and surveillance follow-up. Here we are discussing the new genetic insights of PPGLs.

Usefulness of functional splicing analysis to confirm precise disease pathogenesis in Diamond-Blackfan anemia caused by intronic variants in RPS19

Diamond-Blackfan anemia (DBA) is mainly caused by pathogenic variants in ribosomal proteins and 22 responsible genes have been identified to date. The most common causative gene of DBA is RPS19 [NM_001022.4]. Nearly 180 RPS19 variants have been reported, including three deep intronic variants outside the splicing consensus sequence (c.72-92A > G, c.356 + 18G > C, and c.411 + 6G > C). We also identified one case with a c.412-3C > G intronic variant. Without conducting transcript analysis, the pathogenicity of these variants is unknown. However, it is difficult to assess transcripts because of their fragility. In such cases, in vitro functional splicing assays can be used to assess pathogenicity. Here, we report functional splicing analysis results of four RPS19 deep intronic variants identified in our case and in previously reported cases. One splicing consensus variant (c.411 + 1G > A) was also examined as a positive control. Aberrant splicing with a 2-bp insertion between exons 5 and 6 was identified in the patient samples and minigene assay results also identified exon 6 skipping in our case. The exon 6 skipping transcript was confirmed by further evaluation using quantitative RT-PCR. Additionally, minigene assay analysis of three reported deep intronic variants revealed that none of them showed aberrant splicing and that these variants were not considered to be pathogenic. In conclusion, the minigene assay is a useful method for functional splicing analysis of inherited disease.

Mechanisms of cellular iron sensing, regulation of erythropoiesis and mitochondrial iron utilization

To maintain an adequate iron supply for hemoglobin synthesis and essential metabolic functions while counteracting iron toxicity, humans and other vertebrates have evolved effective mechanisms to conserve and finely regulate iron concentration, storage, and distribution to tissues. At the systemic level, the iron-regulatory hormone hepcidin is secreted by the liver in response to serum iron levels and inflammation. Hepcidin regulates the expression of the sole known mammalian iron exporter, ferroportin, to control dietary absorption, storage and tissue distribution of iron. At the cellular level, iron regulatory proteins 1 and 2 (IRP1 and IRP2) register cytosolic iron concentrations and post-transcriptionally regulate the expression of iron metabolism genes to optimize iron availability for essential cellular processes, including heme biosynthesis and iron-sulfur cluster biogenesis. Genetic malfunctions affecting the iron sensing mechanisms or the main pathways that utilize iron in the cell cause a broad range of human diseases, some of which are characterized by mitochondrial iron accumulation. This review will discuss the mechanisms of systemic and cellular iron sensing with a focus on the main iron utilization pathways in the cell, and on human conditions that arise from compromised function of the regulatory axes that control iron homeostasis.

Multidisciplinary practice guidelines for the diagnosis, genetic counseling and treatment of pheochromocytomas and paragangliomas

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors that arise from chromaffin cells of the adrenal medulla and the sympathetic/parasympathetic neural ganglia, respectively. The heterogeneity in its etiology makes PPGL diagnosis and treatment very complex. The aim of this article was to provide practical clinical guidelines for the diagnosis and treatment of PPGLs from a multidisciplinary perspective, with the involvement of the Spanish Societies of Endocrinology and Nutrition (SEEN), Medical Oncology (SEOM), Medical Radiology (SERAM), Nuclear Medicine and Molecular Imaging (SEMNIM), Otorhinolaryngology (SEORL), Pathology (SEAP), Radiation Oncology (SEOR), Surgery (AEC) and the Spanish National Cancer Research Center (CNIO). We will review the following topics: epidemiology; anatomy, pathology and molecular pathways; clinical presentation; hereditary predisposition syndromes and genetic counseling and testing; diagnostic procedures, including biochemical testing and imaging studies; treatment including catecholamine blockade, surgery, radiotherapy and radiometabolic therapy, systemic therapy, local ablative therapy and supportive care. Finally, we will provide follow-up recommendations.

Pheochromocytoma as a cause of repeated acute myocardial infarctions, heart failure, and transient erythrocytosis: A case report and review of the literature

BACKGROUND

Pheochromocytoma is a rare catecholamines-secreting tumor arising from chromaffin cells in the adrenal medulla. It classically presents with paroxysmal hypertension, headaches, palpitations, sweating, and metabolic disorders. Atypical presentations such as acute myocardial infarction, heart failure, cardiomyopathy, stroke, and transient erythrocytosis have been infrequently documented.

CASE SUMMARY

We describe the case of a 72-year-old man diagnosed with pheochromocytoma presenting with non-ST segment elevation myocardial infarction, heart failure, and transient erythrocytosis with nonobstructed coronary arteries. This was his second heart attack. The patient was previously diagnosed with myocardial infarction, and an immense mass was found on the left adrenal gland 3 years prior. Based on clinical and laboratory findings, a diagnosis of pheochromocytoma was confirmed. His coronary angiogram showed nonobstructed coronary arteries except for a myocardial bridge in the left anterior descending branch. This was a form of type-2 myocardial infarction. The myocardial cell lesions were caused by sudden secretion of catecholamines by the pheochromocytoma. Even more atypically, his hemoglobin level was obviously elevated at admission, but after a few days of treatment with an alpha-adrenergic receptor blocker, it dropped to normal levels without additional treatment.

CONCLUSION

Pheochromocytoma may be a cause of acute myocardial infarction, heart failure, and transient erythrocytosis.

Pheochromocytoma/paraganglioma: recent updates in genetics, biochemistry, immunohistochemistry, metabolomics, imaging and therapeutic options

Pheochromocytomas and paragangliomas (PPGLs), rare chromaffin/neural crest cell tumors, are commonly benign in their clinical presentation. However, there are a number of cases presenting as metastatic and their diagnosis and management becomes a dilemma because of their rarity. PPGLs are constantly evolving entities in the field of endocrinology brought about by endless research and discoveries, especially in genetics. Throughout the years, our knowledge and perception of these tumors and their genetic background has greatly expanded and changed, and each new discovery leads to advancement in the diagnosis, treatment and follow-up of PPGLs. In this review, we discuss the recent updates in the genetics, biochemistry, immunohistochemistry, metabolomics, imaging and treatment options of PPGLs.

Recent Advances in Histopathological and Molecular Diagnosis in Pheochromocytoma and Paraganglioma: Challenges for Predicting Metastasis in Individual Patients

Pheochromocytomas and paragangliomas (PHEO/PGL) are rare but occasionally life-threatening neoplasms, and are potentially malignant according to WHO classification in 2017. However, it is also well known that histopathological risk stratification to predict clinical outcome has not yet been established. The first histopathological diagnostic algorithm for PHEO, "PASS", was proposed in 2002 by Thompson et al. Another algorithm, GAPP, was then proposed by Kimura et al. in 2014. However, neither algorithm has necessarily been regarded a 'gold standard' for predicting post-operative clinical behavior of tumors. This is because the histopathological features of PHEO/PGL are rather diverse and independent of their hormonal activities, as well as the clinical course of patients. On the other hand, recent developments in wide-scale genetic analysis using next-generation sequencing have revealed the molecular characteristics of pheochromocytomas and paragangliomas. More than 30%-40% of PHEO/PGL are reported to be associated with hereditary genetic abnormalities involving > 20 genes, including SDHXs, RET, VHL, NF1, TMEM127, MAX, and others. Such genetic alterations are mainly involved in the pathogenesis of pseudohypoxia, Wnt, and kinase signaling, and other intracellular signaling cascades. In addition, recurrent somatic mutations are frequently detected and overlapped with the presence of genetic alterations associated with hereditary diseases. In addition, therapeutic strategies specifically targeting such genetic abnormalities have been proposed, but they are not clinically applicable at this time. Therefore, we herein review recent advances in relevant studies, including histopathological and molecular analyses, to summarize the current status of potential prognostic factors in patients with PHEO/PGL.

Catecholamine-Secreting Tumors in Pediatric Patients With Cyanotic Congenital Heart Disease

Catecholamine-secreting tumors are rare among the pediatric population but are increasingly being reported in children with sustained hypoxia secondary to cyanotic congenital heart disease (CCHD). With this review, we report the clinical characteristics of these tumors in children with CCHD. The articles included in the present review were identified using PubMed through February 2019. A manual search of the references retrieved from relevant articles was also performed. Pheochromocytomas and paragangliomas (PPGL) in children are commonly associated with high-risk germline or somatic mutations. There is evidently a higher risk of tumorigenesis in children with CCHD as compared with the general pediatric population, even in the absence of susceptible gene mutations. This is due to molecular mechanisms involving the aberrant activation of hypoxia-response elements, likely secondary to sustained hypoxemia, resulting in tumorigenesis. Due to overlapping symptoms with CCHD, the diagnosis of PPGL may be delayed or missed in these patients. We studied all previously reported PPGL cases in children with CCHD and reviewed phenotypic and biochemical features to assess for contributing factors in tumorigenesis. Larger studies are needed to help determine other potential predisposing factors and to establish screening guidelines in this high-risk population. A delay in diagnosis of the PPGL tumors can lead to exacerbation of cardiac failure, and therefore early diagnosis and intervention may provide better outcomes in these patients, necessitating the need for regular surveillance. We recommend routine biochemical screening in patients with sustained hypoxia secondary to CCHD.

Targeting Cyclooxygenase-2 in Pheochromocytoma and Paraganglioma: Focus on Genetic Background

Cyclooxygenase 2 (COX-2) is a key enzyme of the tumorigenesis-inflammation interface and can be induced by hypoxia. A pseudohypoxic transcriptional signature characterizes pheochromocytomas and paragangliomas (PPGLs) of the cluster I, mainly represented by tumors with mutations in von Hippel–Lindau (VHL), endothelial PAS domain-containing protein 1 (EPAS1), or succinate dehydrogenase (SDH) subunit genes. The aim of this study was to investigate a possible association between underlying tumor driver mutations and COX-2 in PPGLs. COX-2 gene expression and immunoreactivity were examined in clinical specimens with documented mutations, as well as in spheroids and allografts derived from mouse pheochromocytoma (MPC) cells. COX-2 in vivo imaging was performed in allograft mice. We observed significantly higher COX-2 expression in cluster I, especially in VHL-mutant PPGLs, however, no specific association between COX-2 mRNA levels and a hypoxia-related transcriptional signature was found. COX-2 immunoreactivity was present in about 60% of clinical specimens as well as in MPC spheroids and allografts. A selective COX-2 tracer specifically accumulated in MPC allografts. This study demonstrates that, although pseudohypoxia is not the major determinant for high COX-2 levels in PPGLs, COX-2 is a relevant molecular target. This potentially allows for employing selective COX-2 inhibitors as targeted chemotherapeutic agents and radiosensitizers. Moreover, available models are suitable for preclinical testing of these treatments.

Update of Pheochromocytoma Syndromes: Genetics, Biochemical Evaluation, and Imaging

Pheochromocytomas and paragangliomas (PCCs/PGLs) are rare commonly benign neuroendocrine tumors that share pathology features and clinical behavior in many cases. While PCCs are chromaffin-derived tumors that arise within the adrenal medulla, PGLs are neural-crest-derived tumors that originate at the extraadrenal paraganglia. Pheochromocytoma-paraganglioma (PPGL) syndromes are rapidly evolving entities in endocrinology and oncology. Discoveries over the last decade have significantly improved our understanding of the disease. These include the finding of new hereditary forms of PPGL and their associated susceptibility genes. Additionally, the availability of new functional imaging tools and advances in targeted radionuclide therapy have improved diagnostic accuracy and provided us with new therapeutic options. In this review article, we present the most recent advances in this field and provide an update of the biochemical classification that further reflects our understanding of the disease.