Pathophysiology and diagnosis of disorders of the adrenal medulla: focus on pheochromocytoma

Update on clinical characteristics in the evaluation of phaeochromocytoma and paraganglioma

Pheochromocytomas and sympathetic paragangliomas (PPGL) are rare neuroendocrine tumors originating from chromaffin tissue of the adrenal medulla and extra-adrenal sympathetic paraganglia. Historically, many of these tumors were diagnosed postmortem, earning pheochromocytomas the moniker "great mimic" due to their diverse clinical manifestations that can resemble various other conditions. Over time, the clinical presentation of PPGL has evolved, with a shift from symptomatic or postmortem diagnoses to more frequent incidental discoveries or diagnoses through screening, with postmortem identification now being rare. The development of a clinical scoring system has improved the identification of patients at increased risk for PPGL. Notably, the proportion of PPGL patients with normal blood pressure ranges from 15 % to 40 %, varying based on the clinical context. Despite the tumor's reputation, PPGL is an exceedingly rare cause of resistant hypertension. Management of a pheochromocytoma crisis has advanced, with several classes of drugs available for treatment. However, PPGL during pregnancy remains a significant concern, associated with substantial maternal and fetal mortality rates. Additionally, PPGL can present as rare disorders, including catecholamine-induced cardiomyopathy, Cushing syndrome, and urinary bladder PGL. Given these varied presentations, heightened awareness and prompt recognition of PPGL are crucial for timely diagnosis and treatment, ultimately improving patient outcomes. In this article, we offer an in-depth analysis of the diverse clinical presentations of PPGL, highlighting their complexity and the associated diagnostic and treatment strategies.

[Headache and hypertension as a form of presentation of pheochromocytoma and simulating a post-COVID-19 syndrome]

Post-COVID-19 syndrome is a set of symptoms and signs that persist for more than 12 weeks after COVID-19 infection and currently lacks a standardised clinical definition. Only one case has been reported in which a pheochromocytoma was mistaken for post-COVID-19 syndrome. The symptomatology of this syndrome is variable and ranges from headache and fatigue to persistent dyspnoea and neurocognitive disturbances. In addition, SARS-CoV-2 can affect the autonomic nervous system, contributing to symptoms resembling those of pheochromocytoma. The importance and need to discern between COVID-19-related symptoms and other conditions is emphasised, as the specificity of the clinical manifestations of post-COVID-19 syndrome is very low and can be confused with other vital pathologies. A case is presented in which a pheochromocytoma was mistaken for post-COVID-19 syndrome in a patient with no medical history.

Long-Term Outcomes after Surgery for Pheochromocytoma and Sympathetic Paraganglioma

BACKGROUND

The prognosis of pheochromocytoma and sympathetic paraganglioma (PHEO/sPGL) is difficult to predict at the time of diagnosis and long-term follow-up data are scarce, especially for apparently benign and sporadic variants. The aim of the study was to analyze the long-term outcomes in PHEO/sPGL patients.

METHODS

A monocentric series of 170 patients who underwent surgery for PHEO/sPGL was analyzed.

RESULTS

The study cohort included 91 female and 79 males with a median age of 48 years (range 6-83). The majority of PHEO/sPGL cases were considered apparently benign at the time of diagnosis; evident malignant behavior was found in 5% of cases. The overall 10-year risk of recurrence was 13%, but it rose up to 33% at 30 years. The risk of new tumor recurrence was higher in patients with hereditary tumors, but the risk was still significant in patients with apparently sporadic variants (20-year risk: 38% vs. 6.5%, respectively; p < 0.0001). The risk of metastatic recurrence was higher in patients with locally aggressive tumors at diagnosis, but the risk was present also in apparently benign variants (5-year risk: 100% vs. 1%, respectively; p < 0.0001).

CONCLUSIONS

Lifelong follow-up is required not only for hereditary PHEO/sPGL but also for apparently benign and sporadic tumors at diagnosis because of the risk of long-term recurrent disease.

Extracellular Vesicles and Hypertension

Hypertension implicates multiple organs and systems, accounting for the majority of cardiovascular diseases and cardiac death worldwide. Extracellular vesicles derived from various types of cells could transfer a variety of substances such as proteins, lipids, and nucleic acids from cells to cells, playing essential roles in both physiological and pathological processes. Extracellular vesicles are demonstrated to be closely associated with the development of essential hypertension by mediating the renin-angiotensin-aldosterone system and crosstalk between multiple vascular cells. Extracellular vesicles also participate in various kinds of pathogenesis of secondary hypertensions including acute kidney injury, renal parenchymal diseases, kidney transplantation, secretory diseases (primary aldosteronism, pheochromocytoma and paraganglioma, Cushing's syndrome), and obstructive sleep apnea. Extracellular vesicles have been proved to have the potential to be served as new biomarkers in the diagnosis, treatment, and prognosis assessment of hypertension. In the future, large multicenter cohorts are highly in demand for further verifying the sensitivity and specificity of extracellular vesicles as biomarkers.

Case report: Incidentally discovered case of pheochromocytoma as a cause of long COVID-19 syndrome

Pheochromocytomas (PCCs) are rare but potentially lethal tumors that arise from the adrenal medulla. The clinical suspicion and diagnosis of PCC can be challenging due to the non-specific nature of signs and symptoms. In many patients, infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could lead to long-term symptoms including fatigue, headaches, and cognitive dysfunction. Here, we present the case of a patient incidentally diagnosed with an adrenal mass that proved to be a PCC after imaging was performed due to persisting complaints after coronavirus disease 2019 (COVID-19) infection. A 37-year-old male patient was referred to our center because of a right-sided inhomogeneous adrenal mass, incidentally found during a computed tomographic scan of the thorax performed due to cough and dyspnea that persisted after COVID-19 infection. Other complaints that were present prior to COVID-19 infection included profuse sweating, dizziness, exhaustion with chronic fatigue, and concentration difficulties. The patient had no history of hypertension, his blood pressure was normal, and the 24-h ambulatory blood pressure monitoring confirmed normotension but with the absence of nocturnal dipping. Plasma normetanephrine was 5.7-fold above the upper limit (UL) of reference intervals (738 pg/ml, UL = 129 pg/ml), whereas plasma metanephrine and methoxytyramine were normal at 30 pg/ml (UL = 84 pg/ml) and <4 pg/ml (UL = 16 pg/ml), respectively. Preoperative preparation with phenoxybenzamine was initiated, and a 4-cm tumor was surgically resected. Profuse sweating as well as dizziness was resolved after adrenalectomy pointing toward PCC and not COVID-19-associated patient concerns. Altogether, this case illustrates the difficulties in recognizing the possibility of PCC due to the non-specific nature of signs and symptoms of the tumor, which in this case did not include hypertension and coincided with some of the symptoms of long COVID-19.

Special situations in pheochromocytomas and paragangliomas: pregnancy, metastatic disease, and cyanotic congenital heart diseases

The aim of our study was to describe the epidemiology, diagnosis, and treatment of the most complex pheochromocytoma and paraganglioma (PGL) cases, including pheochromocytoma/PGL during pregnancy, in cyanotic congenital heart diseases (CCHDs), and metastatic pheochromocytoma. The English and Spanish literature was thoroughly evaluated searching for articles reporting clinical studies, case reports, or reviews of pheochromocytoma/PGL in pregnancy and in CCHD and metastatic pheochromocytoma/PGL. Particular settings in the diagnosis and management of pheochromocytoma and PGLs remain challenging. Those special situations include the diagnosis during pregnancy or in the context of CCHD since the typical clinical features of pheochromocytoma may be confounded with preeclampsia during pregnancy and with the complications commonly observed in CCHD. In addition, although some clinical and genetic features have been associated with higher risk of metastatic pheochromocytoma, the detection and prediction of the development of metastatic disease involve another complex situation that may require special hormonal determinations as plasmatic 3-methoxytyramine and nuclear medicine studies including ¹⁸FDG PET-CT or ¹⁸F-FDOPA PET-CT, among others. Furthermore, the selection of the most appropriate treatment in these situations, as well as the moment to carry it out, requires special care as limited evidence is available. This article reviews the epidemiology, diagnosis, and treatment of the pheochromocytoma/PGL during pregnancy, metastatic pheochromocytoma/PGL, and pheochromocytoma/PGL in CCHD. The diagnosis, and especially the treatment, of metastatic pheochromocytomas and pheochromocytoma/PGL during pregnancy and in CCHD is challenging. Thus, these cases should be management in reference centres by multidisciplinary teams specialized in the pheochromocytoma/PGL treatment.

HIF2α regulates the synthesis and release of epinephrine in the adrenal medulla

The adrenal gland and its hormones regulate numerous fundamental biological processes; however, the impact of hypoxia signaling on adrenal function remains poorly understood. Here, we reveal that deficiency of HIF (hypoxia inducible factors) prolyl hydroxylase domain protein-2 (PHD2) in the adrenal medulla of mice results in HIF2α-mediated reduction in phenylethanolamine N-methyltransferase (PNMT) expression, and consequent reduction in epinephrine synthesis. Simultaneous loss of PHD2 in renal erythropoietin (EPO)-producing cells (REPCs) stimulated HIF2α-driven EPO overproduction, excessive RBC formation (erythrocytosis), and systemic hypoglycemia, which is necessary and sufficient to enhance exocytosis of epinephrine from the adrenal medulla. Based on these results, we propose that the PHD2-HIF2α axis in the adrenal medulla regulates the synthesis of epinephrine, whereas in REPCs, it indirectly induces the release of this hormone. Our findings are also highly relevant to the testing of small molecule PHD inhibitors in phase III clinical trials for patients with renal anemia. KEY MESSAGES: HIF2α and not HIF1α modulates PNMT during epinephrine synthesis in chromaffin cells. The PHD2-HIF2α-EPO axis induces erythrocytosis and hypoglycemia. Reduced systemic glucose facilitates exocytosis of epinephrine from adrenal gland.

Pheochromocytoma and Pregnancy

Pheochromocytoma during pregnancy, although rare, is a perilous condition. The wellbeing of mother and fetus are at stake if not diagnosed and treated antenatally and timely. The diagnosis is frequently overlooked because of the aspecific nature of signs and symptoms and confusion with pregnancy-related hypertension. Measurements of plasma or urinary free metanephrines have the highest diagnostic accuracy. MRI is preferred over ultrasonography. The optimal time for surgical removal is before 24 weeks of gestation or at/after delivery. Laparoscopic adrenalectomy should be preceded by medical pretreatment. Cesarean delivery is preferred in these patients; vaginal delivery might be considered in selected pretreated patients.

Intricacies of the Molecular Machinery of Catecholamine Biosynthesis and Secretion by Chromaffin Cells of the Normal Adrenal Medulla and in Pheochromocytoma and Paraganglioma

The adrenal medulla is composed predominantly of chromaffin cells producing and secreting the catecholamines dopamine, norepinephrine, and epinephrine. Catecholamine biosynthesis and secretion is a complex and tightly controlled physiologic process. The pathways involved have been extensively studied, and various elements of the underlying molecular machinery have been identified. In this review, we provide a detailed description of the route from stimulus to secretion of catecholamines by the normal adrenal chromaffin cell compared to chromaffin tumor cells in pheochromocytomas. Pheochromocytomas are adrenomedullary tumors that are characterized by uncontrolled synthesis and secretion of catecholamines. This uncontrolled secretion can be partly explained by perturbations of the molecular catecholamine secretory machinery in pheochromocytoma cells. Chromaffin cell tumors also include sympathetic paragangliomas originating in sympathetic ganglia. Pheochromocytomas and paragangliomas are usually locally confined tumors, but about 15% do metastasize to distant locations. Histopathological examination currently poorly predicts future biologic behavior, thus long term postoperative follow-up is required. Therefore, there is an unmet need for prognostic biomarkers. Clearer understanding of the cellular mechanisms involved in the secretory characteristics of pheochromocytomas and sympathetic paragangliomas may offer one approach for the discovery of novel prognostic biomarkers for improved therapeutic targeting and monitoring of treatment or disease progression.

Severe hemodynamic instability during elective surgery for a patient with a giant pheochromocytoma: A case report

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A huge pheochromocytoma measuring 16 cm × 15 cm × 10 cm is rare.

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Despite adequate preoperative and intraoperative management, the patient developed severe hypertension followed by a hypotension crisis which were almost lethal.

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Through multidisciplinary management with appropriate resuscitative measures, the huge tumor was resected en bloc with a R0 resection.

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The patient recovered well postoperatively and was free of hypertension.

Introduction

We present a patient with a huge pheochromocytoma who ran a stormy intraoperative course.

Presentation of case

A 57-year-old woman underwent elective open surgery for a giant pheochromocytoma (16 × 15 × 10 cm) after adequate preoperative medical preparation. The patient developed severe hypertension on tumor mobilization followed bylife-threatening hypotensionwhen the tumor was removed. The hemodynamic instability was successfully managed. Histology showed a pheochromocytomawith tumor-free resection margins. The patient fully recoveredandthe hypertension completely resolved after the operation.

Discussion

This is a rare and educational case report on a patient with a huge pheochromocytoma who was successfully managed by a multidisciplinary team of specialists.

Conclusion

Pheochromocytoma should be resected if technically possible. A multidisciplinary team approach is required for proper management.

Tumor characteristics and surgical outcome in incidentally discovered pheochromocytomas and paragangliomas

OBJECTIVE

The proportion of incidentally discovered pheochromocytomas and paragangliomas(PPGL) has increased over time. However, our knowledge of them is quite limited. The purpose of this retrospective study is to generalize the commonalities in incidentally discovered PPGL, offer evidences for clinical diagnosis and management.

METHODS

526 patients were included in our study after filtration from the database of West China Hospital of Sichuan University between May, 2007 and December, 2016.Among the patients, 148 of them were incidental findings and 378 of them were suspected findings. All patients' demography and tumor characteristics were recorded in detail, especially hemodynamic records and hormonal assays. The reasons for taking radiography were also collected. Most patients received preoperative medical preparation . Intraoperative and postoperative courses as well as surgical outcomes were also analyzed to identify differences between incidental findings and suspected findings.

RESULTS

Incidentally discovered PPGL took up 28.1% of the study population. Suspected PPGLs had a higher prevalence of hypertension, lower proportion of non-functioning PPGL, higher prevalence of MEN2 and better post-surgical blood pressure recovery than incidental finding group. However, patients in the incidental finding group showed no significant difference in preoperative blood pressure and hormonal assays with suspected findings in metaphrine and normetaphrine in plasma and urine (P>0.05).

CONCLUSIONS

Due to the development of technology, more PPGLs are discovered incidentally. Considering the tumor characteristics and surgical outcome, surgical decisions should be made more cautiously.

Bortezomib Alone and in Combination With Salinosporamid A Induces Apoptosis and Promotes Pheochromocytoma Cell Death In Vitro and in Female Nude Mice

Proteasome inhibitors have been frequently used in treating hematologic and solid tumors. They are administered individually or in combination with other regimens, to prevent severe side effects and resistance development. Because they have been shown to be efficient and are pharmaceutically available, we tested the first Food and Drug Administration-approved proteasome inhibitor bortezomib alone and in combination with another proteasome inhibitor, salinosporamid A, in pheochromocytoma cells. Pheochromocytomas/Paragangliomas (PHEOs/PGLs) are neuroendocrine tumors for which no definite cure is yet available. Therefore, drugs with a wide spectrum of mechanisms of action are being tested to identify suitable candidates for PHEO/PGL treatment. In the current study, we show that bortezomib induces PHEO cell death via the apoptotic pathway in vitro and in vivo. The combination of bortezomib with salinosporamid A exhibits additive effect on these cells and inhibits proliferation, cell migration and invasion, and angiogenesis more potently than bortezomib alone. Altogether, we suggest these proteasome inhibitors, especially bortezomib, could be potentially tested in PHEO/PGL patients who might benefit from treatment with either the inhibitors alone or in combination with other treatment options.

Update on Modern Management of Pheochromocytoma and Paraganglioma

Despite all technical progress in modern diagnostic methods and treatment modalities of pheochromocytoma/paraganglioma, early consideration of the presence of these tumors remains the pivotal link towards the best possible outcome for patients. A timely diagnosis and proper treatment can prevent the wide variety of potentially catastrophic cardiovascular complications. Modern biochemical testing should include tests that offer the best available diagnostic performance, measurements of metanephrines and 3-methoxytyramine in plasma or urine. To minimize false-positive test results particular attention should be paid to pre-analytical sampling conditions. In addition to anatomical imaging by computed tomography (CT) or magnetic resonance imaging, new promising functional imaging modalities of photon emission tomography/CT using with somatostatin analogues such as ⁶⁸Ga-DOTATATE (⁶⁸Ga-labeled DOTA(0)-Tyr(3)-octreotide) will probably replace ¹²³I-MIBG (iodine-123-metaiodobenzylguanidine) in the near future. As nearly half of all pheochromocytoma patients harbor a mutation in one of the 14 tumor susceptibility genes, genetic testing and counseling should at least be considered in all patients with a proven tumor. Post-surgical annual follow-up of patients by measurements of plasma or urinary metanephrines should last for at least 10 years for timely detection of recurrent or metastatic disease. Patients with a high risk for recurrence or metastatic disease (paraganglioma, young age, multiple or large tumors, genetic background) should be followed up lifelong.

Adrenal Pathology in the Adult: A Urological Pathologist's Perspective

Adrenal gland diagnostics can pose significant challenges. In most academic and community practice settings, adrenal gland resections are encountered less frequently than other endocrine or genitourinary specimens, leading to less familiarity with evolving classifications and criteria. The unique dichotomy between cortical and medullary lesions reflects the developmental evolution of these functionally independent components. Adrenal cortical lesions at resection include hyperplasia, adenoma, and carcinoma, with some cases straddling the boundary between these distinct clinical classifications. The lack of immunohistochemical or molecular markers to definitively categorize these intermediate lesions enhances the diagnostic challenge. In addition, modified terminology for oncocytic and myxoid cortical lesions has been proposed. Medullary lesions are somewhat easier to categorize; however, the prediction of aggressive behavior in pheochromocytomas remains a challenge due to a lack of reliable prognostic biomarkers. Recent work by the Cancer Genome Atlas Project and other research groups has identified a limited subset of molecular and signaling pathway alterations in these 2 major neoplastic categories. Ongoing research to better define prognostic and predictive biomarkers in cortical and medullary lesions has the potential to enhance both pathologic diagnosis and patient therapy.