Biochemical Assessment of Pheochromocytoma and Paraganglioma.

Pheochromocytoma and paraganglioma (PPGL) require prompt consideration and efficient diagnosis and treatment to minimize associated morbidity and mortality. Once considered, appropriate biochemical testing is key to diagnosis. Advances in understanding catecholamine metabolism have clarified why measurements of the O-methylated catecholamine metabolites rather than the catecholamines themselves are important for effective diagnosis. These metabolites, normetanephrine and metanephrine, produced respectively from norepinephrine and epinephrine, can be measured in plasma or urine, with choice according to available methods or presentation of patients. For patients with signs and symptoms of catecholamine excess, either test will invariably establish the diagnosis, whereas the plasma test provides higher sensitivity than urinary metanephrines for patients screened due to an incidentaloma or genetic predisposition, particularly for small tumors or in patients with an asymptomatic presentation. Additional measurements of plasma methoxytyramine can be important for some tumors, such as paragangliomas, and for surveillance of patients at risk of metastatic disease. Avoidance of false-positive test results is best achieved by plasma measurements with appropriate reference intervals and preanalytical precautions, including sampling blood in the fully supine position. Follow-up of positive results, including optimization of preanalytics for repeat tests or whether to proceed directly to anatomic imaging or confirmatory clonidine tests, depends on the test results, which can also suggest likely size, adrenal vs extra-adrenal location, underlying biology, or even metastatic involvement of a suspected tumor. Modern biochemical testing now makes diagnosis of PPGL relatively simple. Integration of artificial intelligence into the process should make it possible to fine-tune these advances.

Algorithmic assessment of missense mutation severity in the Von-Hippel Lindau protein.

Von Hippel-Lindau disease (VHL) is an autosomal dominant rare disease that causes the formation of angiogenic tumors. When functional, pVHL acts as an E3 ubiquitin ligase that negatively regulates hypoxia inducible factor (HIF). Genetic mutations that perturb the structure of pVHL result in dysregulation of HIF, causing a wide array of tumor pathologies including retinal angioma, pheochromocytoma, central nervous system hemangioblastoma, and clear cell renal carcinoma. These VHL-related cancers occur throughout the lifetime of the patient, requiring frequent intervention procedures, such as surgery, to remove the tumors. Although VHL is classified as a rare disease (1 in 39,000 to 1 in 91,000 affected) there is a large heterogeneity in genetic mutations listed for observed pathologies. Understanding how these specific mutations correlate with the myriad of observed pathologies for VHL could provide clinicians insight into the potential severity and onset of disease. Using a select set of 285 ClinVar mutations in VHL, we developed a multiparametric scoring algorithm to evaluate the overall clinical severity of missense mutations in pVHL. The mutations were assessed according to eight weighted parameters as a comprehensive evaluation of protein misfolding and malfunction. Higher mutation scores were strongly associated with pathogenicity. Our approach establishes a novel in silico method by which VHL-specific mutations can be assessed for their severity and effect on the biophysical functions of the VHL protein.

Minimally invasive adrenalectomy results in equivalent perioperative outcomes versus open adrenalectomy for adrenal mass larger than 6 cm: A retrospective propensity score-matched study.

INTRODUCTION: The indication for choosing the minimally invasive approach for large adrenal mass remains controversial. This study is to assess perioperative outcomes after minimally invasive adrenalectomy (MIA) versus open adrenalectomy (OA) for adrenal mass ≥ 6 cm. MATERIALS AND METHODS: A cohort of 173 patients underwent adrenalectomy for adrenal mass ≥ 6 cm in our urology center between May 2005 and April 2018 was included. MIA was performed in 96 patients, whereas 77 patients underwent OA. We performed a retrospective propensity score-matched study to compare MIA versus OA. RESULTS: After propensity score-matched, 58 matched pairs of patients identified from each group. There were no significant differences between the groups in postoperative morbidity (p = 0.146), operative time (p = 0.163), intraoperative hypertension (p = 0.248) and drainage time (p = 0.188). Estimated blood loss, the rate of blood transfusions postoperative hospital stay was less in MIA group (p < 0.0001; p = 0.007; p < 0.0001). Total expense was significantly more in the MIA group [49379.28 (38496.69, 68008.69) CNY vs 39951.48 (30666.33, 50292.03) CNY, p = 0.001]. CONCLUSIONS: MIA results in equivalent perioperative outcomes compared with OA and is an effective and safe surgical method for patients with an adrenal mass more than 6 cm in diameter.

From clinic to mechanism: Proteomics-based assessment of angiogenesis in adrenal pheochromocytoma.

Adrenal pheochromocytoma (PCC) is a very rare tumor that stems from chromaffin cells, which can develop into malignant tumor. During the operation, abundant blood vessels were often observed in PCC than other adrenal tumors, which increases the difficulty and risk of the surgery. Therefore, it is important to investigate the mechanism of PCC angiogenesis. Twelve surgical specimens of PCC from Ruijin Hospital, Shanghai Jiaotong University were grouped into high and low microvessel density (MVD) group. They were also divided into rich blood supply and nonenriched blood supply group, according to computed tomography (CT) manifestation. Comparative proteomic analysis based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) and bioinformatics analysis revealed that 206 proteins differentially regulated in the high MVD group compared with low MVD group (p < 0.05). Besides, 61 proteins were discovered to be significantly changed when the 12 samples were grouped according to CT manifestation. By intersecting the differentially changed protein from MVD and CT grouping, 25 proteins were filtered out, with pathological function. COX4I2 was verified to be increased gradually with angiogenesis with increasing severity, and PLAT was shown to be decreased with angiogenesis in PCC, by quantitative reverse-transcription polymerase chain reaction and immunohistochemistry. The quantitative proteomics result indicated that the tumor angiogenesis in PCC is associated with hypoxia. COX4I2 and PLAT were highly correlated with blood supply in PCC which contribute to angiogenesis in PCC, which could be used as biomarkers to better indicate tumor angiogenesis, or targets to regress tumor angiogenesis as treatment.

Assessment of the potential activity of major dietary compounds as selective estrogen receptor modulators in two distinct cell models for proliferation and differentiation.

Estrogen receptors (ERs) α and ß are distributed in most tissues of women and men. ERs are bound by estradiol (E2), a natural hormone, and mediate the pleiotropic and tissue-specific effects of E2, such as proliferation of breast epithelial cells or protection and differentiation of neuronal cells. Numerous environmental molecules, called endocrine disrupting compounds, also interact with ERs. Phytoestrogens belong to this large family and are considered potent therapeutic molecules that act through their selective estrogen receptor modulator (SERM) activity. Using breast cancer cell lines as a model of estrogen-dependent proliferation and a stably ER-expressing PC12 cell line as a model of neuronal differentiating cells, we studied the SERM activity of major dietary compounds, such as apigenin, liquiritigenin, daidzein, genistein, coumestrol, resveratrol and zearalenone. The ability of these compounds to induce ER-transactivation and breast cancer cell proliferation and enhance Nerve Growth Factor (NGF) -induced neuritogenesis was assessed. Surprisingly, although all compounds were able to activate the ER through an estrogen responsive element reporter gene, they showed differential activity toward proliferation or differentiation. Apigenin and resveratrol showed a partial or no proliferative effect on breast cancer cells but fully contributed to the neuritogenesis effect of NGF. However, daidzein and zearalenone showed full effects on cellular proliferation but did not induce cellular differentiation. In summary, our results suggest that the therapeutic potential of phytoestrogens can diverge depending on the molecule and the phenotype considered. Hence, apigenin and resveratrol might be used in the development of therapeutics for breast cancer and brain diseases.

Assessment of clinical and radiologic differences between small and large adrenal pheochromocytomas.

OBJECTIVE: To evaluate differences in clinical and radiologic features of small and large pheochromocytomas. MATERIALS AND METHODS: This study included 39 patients with adrenal pheochromocytomas. Several clinical and radiologic features were statistically analyzed and compared between small and large pheochromocytomas. RESULTS: No significant differences were found in clinical features between them. Small pheochromocytomas had more relatively homogeneous attenuation although large pheochromocytomas had more cystic or necrotic changes. CONCLUSIONS: Pheochromocytomas tend to have different CT imaging features mimicking other tumors according to the size of the tumors. However, clinical features, CT imaging characteristics, and radioisotope activity are not different between small and large pheochromocytomas.

Risk assessment of maternally inherited SDHD paraganglioma and phaeochromocytoma.

BACKGROUND: Germline mutations in the SDHD tumour suppressor gene (11q23.1) predispose to phaeochromocytomas and paragangliomas (PPGL) mainly on a paternal transmission. However, PPGL have been recently reported in three carriers of a maternally inherited SDHD mutation. OBJECTIVE: To assess the risk of PPGL occurrence on maternal transmission of SDHD mutation. METHODS: Pedigrees of 80 SDHD-related families have been reviewed. 35 asymptomatic subjects carrying a maternally transmitted SDHD mutation were identified. 20 of them accepted to benefit from a PPGL imaging screening. RESULTS: A unique histologically proven biochemically negative phaeochromocytoma has been diagnosed in a 35-year-old woman. Molecular investigations carried out on tumour tissue revealed that the loss of heterozygosity encompassed the paternally derived q arm and the maternally derived p arm of chromosome 11. CONCLUSIONS: This study demonstrates that the risk of developing PPGL for a subject carrying a germline SDHD mutation on the maternal allele remains a rare scenario but does exist. Our data suggest an adjustment of current genetic counselling and clinical care recommendations for at-risk subjects. A targeted familial genetic test should be proposed from the age of 18 years to every subject having a mother carrying a germline SDHD mutation and a first medical workup, including imaging, should be recommended to SDHD-positive mutation carriers.

Screening for phaeochromocytoma and paraganglioma: impact of using supine reference intervals for plasma metanephrines with samples collected from fasted/seated patients.

Background The Endocrine Society Clinical Practice Guideline on Phaeochomocytoma and Paraganglioma recommends phlebotomy for plasma-free metanephrines with patients fasted and supine using appropriately defined reference intervals. Studies have shown higher diagnostic sensitivities using these criteria. Further, with seated-sampling protocols, for result interpretation, reference intervals that do not compromise diagnostic sensitivity should be employed. Objective To determine the impact on diagnostic performance and financial cost of using supine reference intervals for result interpretation with our current plasma-free metanephrines fasted/seated-sampling protocol. Methods We conducted a retrospective cohort study of patients who underwent screening for PPGL using plasma-free metanephrines from 2009 to 2014 at Galway University Hospitals. Plasma-free metanephrines were measured using liquid chromatography-tandem mass spectrometry. Supine thresholds for plasma normetanephrine and metanephrine set at 610 pmol/L and 310 pmol/L, respectively, were used. Results A total of 183 patients were evaluated. Mean age of participants was 53.4 (±16.3) years. Five of 183 (2.7%) patients had histologically confirmed PPGL (males, n=4). Using seated reference intervals for plasma-free metanephrines, diagnostic sensitivity and specificity were 100% and 98.9%, respectively, with two false-positive cases. Application of reference intervals established in subjects supine and fasted to this cohort gave diagnostic sensitivity of 100% with specificity of 74.7%. Financial analysis of each pretesting strategy demonstrated cost-equivalence (€147.27/patient). Conclusion Our cost analysis, together with the evidence that fasted/supine-sampling for plasma-free metanephrines, offers more reliable exclusion of PPGL mandates changing our current practice. This study highlights the important advantages of standardized diagnostic protocols for plasma-free metanephrines to ensure the highest diagnostic accuracy for investigation of PPGL.

Familial pheochromocytomas and paragangliomas.

Pheochromocytomas and paragangliomas are neural crest cell tumors of the adrenal medulla and parasympathetic/sympathetic ganglia, respectively, that are often associated with catecholamine production. Genetic research over the years has led to our current understanding of the association 13 susceptibility genes with the development of these tumors. Most of the susceptibility genes are now associated with specific clinical presentations, biochemical makeup, tumor location, and associated neoplasms. Recent scientific advances have highlighted the role of somatic mutations in the development of pheochromocytoma/paraganglioma as well as the usefulness of immunohistochemistry in triaging genetic testing. We can now approach genetic testing in pheochromocytoma/paraganglioma patients in a very organized scientific way allowing for the reduction of both the financial and emotional burden on the patient. The discovery of genetic predispositions to the development of pheochromocytoma/paraganglioma not only facilitates better understanding of these tumors but will also lead to improved diagnosis and treatment of this disease.

Pheochromocytomas and paragangliomas: assessment of malignant potential.

Pheochromocytomas and paragangliomas (PPGLs) are rare catecholamine-secreting tumors which arise from the adrenal glands or sympathetic neuronal tissue. Malignant transformation of these tumors occurs in a significant proportion and may therefore lower overall survival rates. In patients with PPGLs it is impossible to identify malignant disease without the presence of metastatic disease, something which can occur as long as 20 years after initial surgery. Early identification of malignant disease would necessitate a more aggressive treatment approach, something which may result in better disease outcome. We have therefore reviewed possible predictors of malignancy and current developments in order to help clinicians to swiftly assess malignant potential in patients with PPGLs. Currently, there is no absolute marker which can objectively reflect malignant potential. Tumor size is the most reliable predictor and should therefore be used as the baseline characteristic. The combination of various clinical markers (extra-adrenal disease and post-operative hypertension), biochemical markers (high dopamine, high norepinephrine and epinephrine to total catecholamine ratio) and/or histological markers (SNAIL, microRNAs and/or microarray results) can raise or lower the suspicion of malignancy. Furthermore, we discuss how clinical markers may affect biochemical results linked to malignancy, how biochemical results may distinguish hereditary syndromes, the role of imaging in determining malignant potential and tumor detection, and recent results of proposed histological markers.

Laparoscopic simultaneous bilateral adrenalectomy: assessment of feasibility and potential indications.

OBJECTIVE: To report a single-center experience with laparoscopic simultaneous bilateral adrenalectomy (LSBA) and to evaluate its safety, surgical outcomes, and potential indications of the procedure. METHODS: A total of 21 patients underwent LSBA between 2000 and 2010 at our institution. Four patients had bilateral Cushing's syndrome (CS), two had bilateral pheochromocytoma, and one had a bilateral metastatic tumor. Eleven patients had unilateral or bilateral aldosterone-producing adenoma (APA), associated with CS or subclinical CS. Three patients had unilateral APA with contralateral non-functioning adenoma. Partial adrenalectomy was performed first by using with four ports. After the excision of one gland, the contralateral gland was removed after repositioning of the patient. RESULTS: LSBA was completed in all 21 patients without major complications. Mean operative time was 329.7 min and the estimated blood loss was 94.1 mL. Mean tumor size was 21.8 mm. Of the 16 patients receiving an adrenal-sparing procedure, nine of 11 discontinued glucocorticoid replacement after 2 years. The remaining five patients receiving bilateral total adrenalectomy required 0.5-0.75 mg of dexamethasone permanently. No open conversions, no deaths or no adrenal insufficiencies were encountered. CONCLUSIONS: LSBA represents a safe and viable treatment option for selected patients with bilateral adrenal disease.

Clinical significance of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography for the assessment of 131I-metaiodobenzylguanidine therapy in malignant phaeochromocytoma.

PURPOSE: The aim of this study was to evaluate the significance of 2-[18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) in the assessment of the therapeutic response to 131I-metaiodobenzylguanidine (MIBG) in malignant phaeochromocytoma. METHODS: We reviewed the records of 11 patients (7 men and 4 women) with malignant phaeochromocytoma who underwent 131I-MIBG therapy (100-200 mCi). 18F-FDG PET and serum catecholamine assays were performed 3 months before and after the first dose of 131I-MIBG. FDG uptake was evaluated in the observed lesions using the maximum standardised uptake value (SUVmax). The average SUVmax of all lesions (ASUV) was calculated. If more than five lesions were identified, the average SUVmax of the five highest SUVmax (ASUV5) was calculated. The ratio of pre- and post-therapy values was calculated for the highest SUVmax (rMSUV), ASUV (rASUV), ASUV5 (rASUV5), CT diameter (rCT) and serum catecholamine (rCA). Responder (R) and non-responder (NR) groups were defined after a clinical follow-up of at least 6 months according to changes in symptoms, CT, magnetic resonance imaging (MRI) and 123I-MIBG scan. RESULTS: Post-therapy evaluation revealed five R and six NR patients. The size of the target lesions was not significantly different before and after therapy (p>0.05). However, ASUV and ASUV5 were significantly lower in the R group (rASUV 0.64±0.18, rASUV5 0.68±0.17) compared to the NR group (rASUV 1.40±0.54, rASUV5 1.37±0.61) (p<0.05). CONCLUSION: 18F-FDG PET can be potentially used to evaluate the response of malignant phaeochromocytoma to 131I-MIBG therapy.

Evaluation of response in malignant tumors treated with the multitargeted tyrosine kinase inhibitor sorafenib: a multitechnique imaging assessment.

OBJECTIVE: The purpose of this article is to illustrate the characteristic changes induced in different tumor types by the multitargeted tyrosine kinase inhibitor sorafenib. CONCLUSION: Sorafenib reduces tumor perfusion and thereby induces necrosis and often hemorrhage. Malignant tumors treated with sorafenib undergo both morphologic and functional changes; however, the morphologic changes are less frequent and inadequate for early evaluation of response. Therefore, imaging tools accurately assessing hemorrhage and decrease in tumor perfusion with subsequent necrosis should be the mainstay in monitoring targeted therapy agents.

[Diagnostic guidelines for adrenal gland nodules: typing, assessment of biological potential and prognosis, molecular pathogenesis]. / Diagnostische Leitlinien bei Knoten in der Nebenniere: Typisierung, Dignitäts- und Prognoseerfassung, molekulare Pathogenese.

The aim of morphological tumour diagnosis is to answer clinical questions on type, biological potential, prognosis and aetiology of individual neoplasms. The limitations and perspectives of different methods used in the diagnosis of adrenal tumours, ranging from histology to molecular genetic DNA analyses, are described. When surgical specimens from adrenal neoplasms cannot be typed on the basis of histology and/or with clinica data (e.g. endocrine symptoms and history) as adrenocortical tumours, phaeochromocytomas or metastases to the adrenal, immunohistological investigations with a panel of different antibodies are necessary. After identification of the tissue derivation of an individual adrenal tumour, its biological potential must be assessed. Among adrenocortical neoplasms, adenomas and carcinomas can be distinguished by evaluation of various histological parameters (including structural features and signs of invasion) according to defined algorithms. In addition, conventional histology (by estimation of mitotic activity) allows the discrimination of tumours with especially high malignant potential from other adrenocortical carcinomas. In contrast, among adrenomedullary tumours even the combined use of histological, immunohistological and DNA cytophotometric techniques only allows the definition of risk groups (benign versus suggestive of malignancy), while reliable recognition of an individual malignant phaeochromocytoma is so far impossible. The question as to whether a particular phaeochromocytoma represents a sporadic tumour or a neoplasm inherited as one feature of a defined syndrome cannot be answered with the above methods, but only by the application of molecular genetic techniques.

Two-state stochastic models for memory in ion channels.

AIM: To study quantitatively the memory existing in ion channels. METHODS: Stochastic processes were used to model 2 categories of memory (short-term and long-term) by persisting in the standpoint of two-state, instead of multiple states, but with different transition mechanism. RESULTS: A two-state Markov process with constant transition intensities well fitted the short-term memory and a two-state Markov process within a kind of random environment well fitted the long-term memory. Statistical procedures for parameter estimation were proposed and demonstrated with 2 real examples on the channels of PC12 cells. CONCLUSION: The memory in ion channels can be quantitatively modelled as stochastic process with 2 states.

Magnetic resonance imaging for assessment of vena caval tumor thrombi: a comparative study with venacavography and computerized tomography scanning.

We assessed the accuracy of magnetic resonance imaging in demonstrating the presence and extent of vena caval tumor thrombi. The study group included 20 patients with vena caval thrombi from renal cell carcinoma (18), renal pelvic transitional cell carcinoma (1) and adrenal pheochromocytoma (1). Preoperative diagnostic studies included magnetic resonance imaging in all patients, inferior venacavography in 16 and computerized tomography scanning in 15. All patients underwent an operation in which the presence and extent of the vena caval thrombus were confirmed. Magnetic resonance imaging accurately delineated the presence and extent of the thrombus in all 20 patients (100%). Venacavography was accurate in 15 patients (94%) but 8 (50%) required a retrograde and antegrade study. Computerized tomography scanning demonstrated the presence of a tumor thrombus in all 15 patients but accurately delineated the cephalad extent of the thrombus in only 5 (33%). In patients with vena caval tumor thrombi magnetic resonance imaging can provide accurate information regarding the extent of vena caval involvement while avoiding the need for an invasive contrast imaging study.

The role of fine needle aspiration in the assessment of renal masses.

An investigation of the role of fine needle aspiration in the assessment of renal masses was carried out on 132 consecutive patients, 11 of whom were children. Selection was based on the presence of a solid or mixed solid and cystic renal mass that could not be defined by radiology, either in symptomatic patients or in patients to be submitted to embolization of the renal artery and at high surgical risk. Histologic and clinical data showed 49% of the cases to have a malignant, predominantly (45%) primary disease of the kidney and the remainder to have a nonneoplastic lesion. In five cases, the primary lesion was in the adrenal gland (three neuroblastomas and two pheochromocytomas). Sensitivity, specificity and predictive values for positive results were, respectively, 0.93, 0.96 and 0.935 because of a false-positive diagnosis in a case of multilocular cystic nephroma. Furthermore, in 43 of 65 cases (66%), consisting of 33 renal cell carcinomas, 1 transitional cell carcinoma, 3 Wilm's tumors, 1 neuroblastoma, 2 pheochromocytomas and 3 metastatic lesions, the histologic type could be ascertained on the tissue yielded by the fine needle aspiration. The findings stress the usefulness of this method for the clarification of radiologically not unequivocal space-occupying lesions of the renal area, especially when, in addition to the smears, histologic sections of paraffin-embedded tissues are available. Ultrastructural and immunohistochemical studies are cost-effective mainly in pediatric patients.