Biochemical and radiological relationships in patients with pheochromocytoma: lessons from a case control study

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.

A Laboratory Medicine Perspective on the Investigation of Phaeochromocytoma and Paraganglioma

Phaeochromocytomas (PC) and sympathetic paragangliomas (PGL) are potentially malignant tumours arising from the adrenal medulla (PC) or elsewhere in the sympathetic nervous system (PGL). These tumours usually secrete catecholamines and are associated with significant morbidity and mortality, so accurate and timely diagnosis is essential. The initial diagnosis of phaeochromocytoma/paraganglioma (PPGL) is often dependent on biochemical testing. There is a range of pre-analytical, analytical and post-analytical factors influencing the analytical and diagnostic performance of biochemical tests for PPGL. Pre-analytical factors include patient preparation, sample handling and choice of test. Analytical factors include choice of methodology and the potential for analytical interference from medications and other compounds. Important factors in the post-analytical phase include provision of appropriate reference ranges, an understanding of the potential effects of various medications on metanephrine concentrations in urine and plasma and a consideration of PPGL prevalence in the patient population being tested. This article reviews these pre-analytical, analytical and post-analytical factors that must be understood in order to provide effective laboratory services for biochemical testing in the diagnosis of PPGL.

Development of a radiomics model to diagnose pheochromocytoma preoperatively: a multicenter study with prospective validation

Background

Preoperative diagnosis of pheochromocytoma (PHEO) accurately impacts preoperative preparation and surgical outcome in PHEO patients. Highly reliable model to diagnose PHEO is lacking. We aimed to develop a magnetic resonance imaging (MRI)-based radiomic-clinical model to distinguish PHEO from adrenal lesions.

Methods

In total, 305 patients with 309 adrenal lesions were included and divided into different sets. The least absolute shrinkage and selection operator (LASSO) regression model was used for data dimension reduction, feature selection, and radiomics signature building. In addition, a nomogram incorporating the obtained radiomics signature and selected clinical predictors was developed by using multivariable logistic regression analysis. The performance of the radiomic-clinical model was assessed with respect to its discrimination, calibration, and clinical usefulness.

Results

Seven radiomics features were selected among the 1301 features obtained as they could differentiate PHEOs from other adrenal lesions in the training (area under the curve [AUC], 0.887), internal validation (AUC, 0.880), and external validation cohorts (AUC, 0.807). Predictors contained in the individualized prediction nomogram included the radiomics signature and symptom number (symptoms include headache, palpitation, and diaphoresis). The training set yielded an AUC of 0.893 for the nomogram, which was confirmed in the internal and external validation sets with AUCs of 0.906 and 0.844, respectively. Decision curve analyses indicated the nomogram was clinically useful. In addition, 25 patients with 25 lesions were recruited for prospective validation, which yielded an AUC of 0.917 for the nomogram.

Conclusion

We propose a radiomic-based nomogram incorporating clinically useful signatures as an easy-to-use, predictive and individualized tool for PHEO diagnosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03233-w.

Plasma metanephrines and prospective prediction of tumor location, size and mutation type in patients with pheochromocytoma and paraganglioma

Objectives

Plasma free metanephrines are commonly used for diagnosis of pheochromocytoma and paraganglioma (PPGLs), but can also provide other information. This multicenter study prospectively examined whether tumor size, location, and mutations could be predicted by these metabolites.

Methods

Predictions of tumor location, size, and mutation type, based on measurements of plasma normetanephrine, metanephrine, and methoxytyramine were made without knowledge of disease in 267 patients subsequently determined to have PPGLs.

Results

Predictions of adrenal vs. extra-adrenal locations according to increased plasma concentrations of metanephrine and methoxytyramine were correct in 93 and 97% of the respective 136 and 33 patients in who these predictions were possible. Predicted mean tumor diameters correlated positively (p<0.0001) with measured diameters; predictions agreed well for pheochromocytomas but were overestimated for paragangliomas. Considering only patients with mutations, 51 of the 54 (94%) patients with NF1 or RET mutations were correctly predicted with those mutations according to increased plasma metanephrine, whereas no or minimal increase in metanephrine correctly predicted all 71 patients with either VHL or SDHx mutations; furthermore, among the latter group increases in methoxytyramine correctly predicted SDHx mutations in 93% of the 29 cases for this specific prediction.

Conclusions

Extents and patterns of increased plasma O-methylated catecholamine metabolites among patients with PPGLs allow predictions of tumor size, adrenal vs. extra-adrenal locations and general types of mutations. Predictions of tumor location are, however, only possible for patients with clearly increased plasma methoxytyramine or metanephrine. Where possible or clinically relevant the predictions are potentially useful for subsequent clinical decision-making.

Not all adrenal incidentalomas require biochemical testing to exclude pheochromocytoma: Mayo clinic experience and a meta-analysis

Background

Excluding a pheochromocytoma is important when a patient presents with an incidentally discovered adrenal mass. However, biochemical testing for pheochromocytoma can be cumbersome, time consuming, or falsely positive. Our objective was to determine if unenhanced computed tomography (CT) imaging alone can be used to rule out pheochromocytoma.

Methods

We performed a retrospective study of all patients with a pathologically confirmed pheochromocytoma and unenhanced CT imaging who were treated at the Mayo Clinic between 1998 and 2016. Additionally, we performed a systematic review and meta-analysis of original studies published after 2005 with patients who had adrenal masses, more than 10 patients with pheochromocytomas, and reported attenuation on unenhanced CT imaging in Hounsfield units (HU).

Results

In the Mayo cohort, we identified 186 patients and 199 pheochromocytomas with unenhanced CT imaging. The mean unenhanced CT attenuation was 35±9 HU (range, 15-62), and only 15 tumors had attenuation ≤20 HU. The systematic review identified 26 studies (1,217 tumors), and 23 studies provided a mean unenhanced CT attenuation. The overall mean unenhanced CT attenuation across the studies was 35.6 HU (95% CI, 22.0-49.1 HU). A cutoff of >10 HU had a 100% sensitivity (95% CI, 1.00-1.00) for pheochromocytoma with low heterogeneity between the 21 qualified studies (I²=0%). Sensitivity for pheochromocytoma was 100% and 99% for an unenhanced CT attenuation cutoff of >15 and >20 HU.

Conclusions

Biochemical testing may not be required to exclude pheochromocytoma if an incidental adrenal mass has low attenuation (<10 HU) on unenhanced CT images.

The effect of combined Epidural-general Anesthesia on Hemodynamic Instability during Pheochromocytoma and Paraganglioma Surgery: A multicenter retrospective cohort study

Objectives: The purpose of this study was to compare the effects of combined epidural-general anesthesia with those of general anesthesia alone on hemodynamic instability (intraoperative hypotension and hypertensive crisis) during pheochromocytoma and sympathetic paraganglioma surgery. Methods: A total of 119 patients' medical records were reviewed who were diagnosed as having pheochromocytoma and sympathetic paraganglioma on the basis of histological findings. Intraoperative hypotension was defined as a mean blood pressure < 60 mmHg or a decrease > 30% in baseline systolic blood pressure after adrenal vein ligation. Hypertensive crisis was defined as a systolic blood pressure > 200 mmHg or an increase > 30% in baseline systolic blood pressure during the operation. The predictor variables for intraoperative hypotension and hypertensive crisis were analyzed with logistic regression models. Data were presented as adjusted odds ratio with 95% confidence interval. Results: The independent predictors of intraoperative hypotension were an increased attenuation number on unenhanced computed tomography (1.112 [1.009-1.226], p = 0.033), a high baseline mean blood pressure (1.063 [1.012-1.117], p = 0.015), and the combined epidural-general anesthesia (5.439 [1.410-20.977], p = 0.014). In contrast, an increased attenuation number on unenhanced computed tomography was the only independent predictor of hypertensive crisis (1.087 [1.021-1.158], p = 0.009). Conclusions: The combined epidural-general anesthesia was not effective in attenuating hypertensive responses, but could have exacerbated intraoperative hypotension. These findings should be taken into account before selecting the anesthetic technique in pheochromocytoma and sympathetic paraganglioma surgery.

Diagnostic Accuracy of Computed Tomography to Exclude Pheochromocytoma: A Systematic Review, Meta-analysis, and Cost Analysis

OBJECTIVES

To assess the diagnostic accuracy of unenhanced computed tomography (CT) attenuation values to exclude a pheochromocytoma in the diagnostic work-up of patients with an adrenal incidentaloma and to model the associated difference in diagnostic costs.

METHODS

The MEDLINE and Embase databases were searched from indexing to September 27, 2018, and studies reporting the proportion of pheochromocytomas on either side of the 10-Hounsfield unit (HU) threshold on unenhanced CT were included. The pooled proportion of pheochromocytomas with an attenuation value greater than 10 HU was determined, as were the modeled financial costs of the current and alternative diagnostic approaches.

RESULTS

Of 2957 studies identified, 31 were included (N=1167 pheochromocytomas). Overall risk of bias was low. Heterogeneity was not observed between studies (Q=11.5, P=.99, I²=0%). The pooled proportion of patients with attenuation values greater than 10 HU was 0.990 (95% CI, 0.984-0.995). The modeled financial costs using the new diagnostic approach were €55 (∼$63) lower per patient.

CONCLUSION

Pheochromocytomas can be reliably ruled out in the case of an adrenal lesion with an unenhanced CT attenuation value of 10 HU or less. Therefore, determination of metanephrine levels can be restricted to adrenal tumors with an unenhanced CT attenuation value greater than 10 HU. Implementing this novel diagnostic strategy is cost-saving.

A clinical prediction model to estimate the metastatic potential of pheochromocytoma/paraganglioma: ASES score

BACKGROUND

Malignant pheochromocytoma and paraganglioma can be defined only after the development of metastases in nonchromaffin tissues. There is no single clinical parameter that is sufficiently reliable to predict metastatic potential, so our goal was to develop a prediction model based on multiple clinical parameters.

METHODS

The baseline age, size, extra-adrenal location, secretory type score was calculated in a retrospective cohort study comprising 333 patients with pheochromocytoma and paraganglioma. In each patient, each variable for age ≤35 years, tumor size ≥ 6.0 cm, extra-adrenal, and norepinephrine-secretory type was coded as 1 point (otherwise 0 point); these points were summed to yield age, size, extra-adrenal location, secretory type score.

RESULTS

Metastases occurred in 23 of 333 patients (6.9%). Metastatic pheochromocytoma and paraganglioma was associated with age ≤35 years (hazard ratio [HR] 2.74, 95% confidence interval [95% CI] 1.19-6.35), tumor size ≥6.0 cm (HR 2.43, 95% CI 1.06-5.56), extra-adrenal location (HR 2.73, 95% confidence interval 1.10-7.40), and tumor producing only norepinephrine (HR 2.96, 95% CI 1.30-6.76). The area under the curve of the age, size, extra-adrenal location, secretory type score was 0.735. There was a significant difference in metastasis-free survival between participants with age, size, extra-adrenal location, secretory type score ≥2 and score <2 (P < .0001 by the log rank test). The negative predictive value of this system was 96.5% for a cutoff point of 2.

CONCLUSION

We developed a new prediction model, the age, size, extra-adrenal location, secretory type score, based on multiple clinical parameters to assess the metastatic potential of pheochromocytoma and paraganglioma.

Unenhanced CT imaging is highly sensitive to exclude pheochromocytoma: a multicenter study

BACKGROUND

A substantial proportion of all pheochromocytomas is currently detected during the evaluation of an adrenal incidentaloma. Recently, it has been suggested that biochemical testing to rule out pheochromocytoma is unnecessary in case of an adrenal incidentaloma with an unenhanced attenuation value ≤10 Hounsfield Units (HU) at computed tomography (CT).

OBJECTIVES

We aimed to determine the sensitivity of the 10 HU threshold value to exclude a pheochromocytoma.

METHODS

Retrospective multicenter study with systematic reassessment of preoperative unenhanced CT scans performed in patients in whom a histopathologically proven pheochromocytoma had been diagnosed. Unenhanced attenuation values were determined independently by two experienced radiologists. Sensitivity of the 10 HU threshold was calculated, and interobserver consistency was assessed using the intraclass correlation coefficient (ICC).

RESULTS

214 patients were identified harboring a total number of 222 pheochromocytomas. Maximum tumor diameter was 51 (39-74) mm. The mean attenuation value within the region of interest was 36 ± 10 HU. Only one pheochromocytoma demonstrated an attenuation value ≤10 HU, resulting in a sensitivity of 99.6% (95% CI: 97.5-99.9). ICC was 0.81 (95% CI: 0.75-0.86) with a standard error of measurement of 7.3 HU between observers.

CONCLUSION

The likelihood of a pheochromocytoma with an unenhanced attenuation value ≤10 HU on CT is very low. The interobserver consistency in attenuation measurement is excellent. Our study supports the recommendation that in patients with an adrenal incidentaloma biochemical testing for ruling out pheochromocytoma is only indicated in adrenal tumors with an unenhanced attenuation value >10 HU.

The Value of Dual-Phase Enhancement CT as a Predictor of the Preoperative Preparation of Adrenal Pheochromocytoma

The purpose of this study was to evaluate the function of adrenal pheochromocytoma with the value of dual-phase enhancement computed tomography (CT) and to guide the preoperative preparation of adrenal pheochromocytoma. From June 2009 to December 2015, the patients with a diagnosis of pheochromocytoma were divided into 2 groups according to the length of preparation time (group 1, ≤2 weeks; group 2, &gt;2 weeks). Two experienced radiologists measured adrenal lesion attenuation from dual-phase, contrast-enhanced CT examinations. Student t-test analysis was performed to compare arterial and venous phase enhancement levels and the maximum increased enhancement CT value. There were 31 cases of pheochromocytoma that were accepted into the study: 13 cases in group 1 and 18 cases in group 2. At contrast-enhanced CT, the mean arterial enhancement and venous enhancement of pheochromocytoma were 74 ± 20 Hounsfield units (HU; range, 50–107 HU) and 72 ± 18 HU (range, 44–109 HU), respectively, in group 1, which were significantly less than those in group 2, with a mean of 101 ± 26 HU (range, 64–138 HU) and 100 ± 22 HU (range, 61–131 HU; P &lt; 0.05). The average maximum increased attenuation at enhancement CT in group 1 was 41 ± 12 HU (range, 24–62 HU), significantly less than that in group 2, with a mean of 62 ± 22 HU (range, 26-102 HU; P &lt; 0.05). The preparation time was related to the absolute enhancement level, especially with the maximum increased attenuation of pheochromocytoma at enhanced CT. More preparation time before surgery was needed if the maximum enhancement level during arterial phase and venous phase was greater than 109 HU and the maximum increased attenuation was greater than 62 HU.

Symptom-dependent cut-offs of urine metanephrines improve diagnostic accuracy for detecting pheochromocytomas in two separate cohorts, compared to symptom-independent cut-offs

The development of advanced imaging techniques has increased the detection of subclinical pheochromocytomas. Because of the substantial proportions of subclinical pheochromocytomas, measurement of urine metanephrine concentrations is crucial due to detect or exclude pheochromocytoma. Although urine metanephrines are elevated in symptomatic subjects, diagnostic cut-offs according to the presence of adrenergic symptoms have not been studied. Pheochromocytomas patients who underwent adrenalectomy at Samsung Medical Center and a control group were compared to determine cut-off concentrations of urine metanephrines. An independent population was analyzed for urine metanephrines with different kits to validate the improvement in diagnostic accuracy using adjusted cut-offs. Symptom-dependent cut-offs of urine metanephrines were higher for symptomatic patients (307 μg/day in males, 235 μg/day in females for urine metanephrine, and 1,045 μg/day in males and 457 μg/day in females for urine normetanephrine) than for asymptomatic patients (206 μg/day in males, 199 μg/day in females for urine metanephrine, and 489 μg/day in males and 442 μg/day in females for urine normetanephrine). Symptom-dependent cut-offs of urine metanephrines improved a specificity from 92.7 % to 96.3 % and a high sensitivity of 97.8 % was maintained. Using the Symptom-dependent cut-offs raised diagnostic accuracy by 5.5 % (p <0.001). Similar trend was also observed in an independent population using different hormone kits. Using symptom-dependent cut-offs of urine metanephrines in symptomatic patients for pheochromocytomas resulted in a significant improvement in diagnostic accuracy in two separate cohorts.

Urinary clonidine suppression testing for the diagnosis of pheochromocytoma

OBJECTIVE

The diagnosis of pheochromocytoma/paraganglioma (PPGL) involves detection of elevated levels of plasma and/or 24-h urine catecholamines and/or their metabolites, including metanephrines. Although these tests are reasonably sensitive, false-positive results are often encountered. Follow-up tests can provide additional information to correctly diagnose PPGL. In this regard, the utility of the urinary clonidine suppression test (UCST) remains unknown.

METHODS

To assess the diagnostic accuracy of the UCST in confirming or excluding PPGL, we conducted a retrospective analysis of all patients who underwent a UCST between 2000 and 2013 (n = 59; 15 PPGLs) at a single centre. Twelve-hour urine catecholamines and metanephrines were assessed before and after clonidine administration, and examined in relation to final diagnosis, PPGL or non-PPGL. Receiver operating characteristic analyses were used to identify optimal positivity cut-offs. Sensitivity, specificity, positive and negative predictive values were calculated.

RESULTS

Clonidine significantly decreased urine creatinine-corrected norepinephrine and normetanephrine in patients without PPGL (P < 0.001 pairwise) but not in patients with PPGL. Epinephrine and metanephrine levels were not significantly reduced in either group. Receiver operating characteristic (ROC) area under the curve was 0.955 [95% confidence interval (95% CI) 0.906-1.000, P < 0.001] and 0.823 (95% CI 0.706-0.940, P < 0.001) for norepinephrine and normetanephrine, respectively. Optimal cut-offs were established at 50 and 15% reductions in norepinephrine and normetanephrine, respectively, which provided high sensitivities (93.3% for both) and negative predictive values (97.4 and 96.3%). When both were concordant, higher diagnostic accuracy was achieved (100% sensitivity, 92.0% specificity). Results were similar in subgroups of individuals with borderline initial testing (n = 40) or on interfering drugs (n = 25).

CONCLUSION

The UCST appears to be a highly accurate test for PPGL. Further prospective studies are needed to validate these results before routine use is encouraged.

Adrenal incidentalomas: a disease of modern technology offering opportunities for improved patient care

Adrenal incidentalomas (AIs) are found in approximately 4% of patients undergoing abdominal imaging, with peak prevalence in the sixth and seventh decades of life. Detection of AI warrants clinical, biochemical, and radiological evaluation to establish its secretory status and risk of malignancy. Careful review of the lipid content, size, and imaging phenotype of an adrenal mass is needed to evaluate the risk for malignancy. Identification of an AI may be an opportunity to identify an underlying secretory tumor that may have been otherwise unrecognized. A practical approach to investigation and follow-up of AIs is presented in this article.

The evaluation and treatment of endocrine forms of hypertension

Endocrine hypertension is an important secondary form of hypertension, identified in between 5% and 10% of general hypertensive population. Primary aldosteronism is the most common cause of endocrine hypertension, accounting for 1%-10% in uncomplicated hypertension and 7%-20% in resistant hypertension. Other less common causes of endocrine hypertension include Cushing syndrome, pheochromocytoma, thyroid disorders, and hyperparathyroidism. Diagnosis requires a high index of suspicion and the use of appropriate screening tests based on clinical presentation. Failure to make proper diagnosis may lead to catastrophic complications or irreversible hypertensive target organ damage. Accordingly, patients who are suspected to have endocrine hypertension should be referred to endocrinologists or hypertension specialists who are familiar with management of the specific endocrine disorders.