Hypoglycemia induced by excessive rebound secretion of insulin after removal of pheochromocytoma

Laparoscopic adrenalectomy for adrenal tumors with endocrine activity: Perioperative management pathways for reduced complications and improved outcomes

The major adrenal tumors with endocrine activity are primary aldosteronism, Cushing's syndrome/mild autonomous cortisol secretion, and pheochromocytoma/paraganglioma. Excessive aldosterone secretion in primary aldosteronism causes cardiovascular, renal, and other organ damage in addition to hypertension and hypokalemia. Cortisol hypersecretion in Cushing's syndrome/mild autonomous cortisol secretion causes obesity, hypertension, impaired glucose tolerance, and cardiometabolic syndrome. Massive secretion of catecholamines in pheochromocytoma/paraganglioma causes hypertension and cerebrocardiovascular disease due to rapid blood pressure fluctuation. Moreover, pheochromocytoma multi-system crisis is a feared and possibly fatal presentation of pheochromocytoma/paraganglioma. Thus, adrenal tumors with endocrine activity are considered an indication for adrenalectomy, and perioperative management is very important. They have a risk of perioperative complications, either due to direct hemodynamic effects of the hormone hypersecretion or due to hormone-related comorbidities. In the last decades, deliberate preoperative evaluation and advanced perioperative management have significantly reduced complications and improved outcomes. Furthermore, improvements in anesthesia and surgical techniques with the feasibility of laparoscopic adrenalectomy have contributed to reduced morbidity and mortality. However, there are still several challenges to be considered in the perioperative care of these patients. There are very few data available prospectively to guide clinical management, due to the rarity of adrenal tumors with endocrine activity. Therefore, most guidelines are based on retrospective data analyses or small case series. In this review, the latest knowledge is summarized, and practical pathways to reduce perioperative complications and improve outcomes in adrenal tumors with endocrine activity are presented.

Pathophysiology and Management of Glycemic Alterations before and after Surgery for Pheochromocytoma and Paraganglioma

Glycemic alterations are frequent in patients with pheochromocytoma and paraganglioma (PPGL), but the real incidence of secondary diabetes mellitus (DM) is uncertain, because prospective multicenter studies on this topic are lacking in the literature. The main pathophysiological mechanisms of glucose homeostasis alterations in PPGL, related to catecholamine hypersecretion, are impaired insulin and glucagon-like peptide type 1 (GLP-1) secretion and increased insulin resistance. Moreover, it has been reported that different pathways leading to glucose intolerance may be related to the secretory phenotype of the chromaffin tumor. Predictive factors for the development of glucose intolerance in PPGL patients are a higher age at diagnosis, the need for a higher number of anti-hypertensive drugs, and the presence of secreting neoplasms. Tumor resection is strongly related to the resolution of DM in PPGL patients, with a significant improvement of glycemic control in most cases. We can hypothesize a different personalized therapeutic approach based on the secretory phenotype. The adrenergic phenotype is more closely related to reduced insulin secretion, so insulin therapy may be required. On the other hand, the noradrenergic phenotype mainly acts by increasing insulin resistance and, therefore, insulin-sensitizing antidiabetic agents can find a greater application. Regarding GLP-1 receptor agonists, the data suggest a possible promising therapeutic effect, based on the assumption that GLP-1 secretion is impaired in patients with PPGL. The principal predictors of remission of glycemic alterations after surgery for PPGL are a lower preoperative body mass index (BMI), a larger tumor, higher preoperative catecholamine levels, and a shorter duration of the disease (under three years). Otherwise, after resection of PPGL, hypoglycemia can occur as the result of an excessive rebound of preoperative hyperinsulinemia. It is a rare, but potentially severe complication reported in a lot of case reports and a few small retrospective studies. Higher 24-h urinary metanephrine levels, longer operative times and larger tumors are predictive factors for hypoglycemia in this setting. In conclusion, alterations of carbohydrate metabolism are clinically relevant manifestations of PPGL before and after surgery, but there is the need to conduct multicenter prospective studies to obtain an adequate sample size, and to allow the creation of shared strategies for the clinical management of these potentially severe manifestations of PPGL.

Type 1 and other types of diabetes mellitus in the perioperative period. What the anaesthetist should know

Diabetes mellitus is often treated as a uniform disease in the perioperative period. Type 2 diabetes is most commonly encountered, and only a minority of surgical patients have been diagnosed with another type of diabetes. Patients with a specific type of diabetes can be particularly prone to perioperative glycaemic dysregulation. In addition, certain type-related features and pitfalls should be taken into account in the operating theatre. In this narrative review, we discuss characteristics of types of diabetes other than type 2 diabetes relevant to the anaesthetist, based on available literature and data from our clinic.

Glycemic disorders in patients with pheochromocytomas and sympathetic paragangliomas

The objective of our study was to determine the prevalence of glycemic disorders (diabetes mellitus and prediabetes) in patients with pheochromocytomas and sympathetic paragangliomas (PPGLs) and identify risk factors for their development and the likelihood of their resolution after surgery. A multicentric retrospective study of patients with PPGLs submitted to surgery between 2000 and 2021 in 17 Spanish hospitals was performed. Diabetes-specific data were collected at diagnosis, in the immediate- and long-term postsurgical follow-up. A total of 229 patients with PPGLs were included (218 with pheochromocytomas and 11 with sympathetic paragangliomas). Before surgery, glycemic disorders were diagnosed in 35.4% of the patients (n = 81): 54 with diabetes and 27 with prediabetes. The variables independently associated with a higher risk of glycemic disorders were sporadic PPGL (odds ratio (OR) = 3.26 (1.14-9.36)) and hypertension (OR = 3.14 (1.09-9.01)). A significant decrease in fasting plasma glucose and HbA1c levels was observed after surgery, in the short-term and long-term follow-up (P < 0.001). After a median follow-up of 48.5 months (range 3.3-168.9), after surgery, 52% of diabetic and 68% of prediabetic patients experienced a complete resolution. Lower body mass index (BMI) (P = 0.001), lower glucose levels (P = 0.047) and shorter duration of diabetes prior to surgery (P = 0.021) were associated with a higher probability of diabetes resolution. In conclusion, glycemic disorders in patients with PPGLs are present in more than a third of them at diagnosis. Sporadic PPGLs and hypertension are risk factors for their development. More than 50% of cases experience a complete resolution of the glycemic disorder after resection of the PPGLs.

Perioperative Management of Pheochromocytomas and Sympathetic Paragangliomas

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors arising from chromaffin cells of the adrenal medulla or extra-adrenal paraganglia, respectively. PPGLs have the highest degree of heritability among endocrine tumors. Currently, ~40% of individuals with PPGLs have a genetic germline and there are at least 12 different genetic syndromes related to these tumors. Metastatic PPGLs are defined by the presence of distant metastases at sites where chromaffin cells are physiologically absent. Approximately 10% of pheochromocytomas and ~40% of sympathetic paragangliomas are linked to metastases, explaining why complete surgical resection is the first-choice treatment for all PPGL patients. The surgical approach is a high-risk procedure requiring perioperative management by a specialized multidisciplinary team in centers with broad expertise. In this review, we summarize and discuss the most relevant aspects of perioperative management in patients with pheochromocytomas and sympathetic paragangliomas.

Update on Pheochromocytoma and Paraganglioma from the SSO Endocrine and Head and Neck Disease Site Working Group, Part 2 of 2: Perioperative Management and Outcomes of Pheochromocytoma and Paraganglioma

This is the second part of a two-part review on pheochromocytoma and paragangliomas (PPGLs). In this part, perioperative management, including preoperative preparation, intraoperative, and postoperative interventions are reviewed. Current data on outcomes following resection are presented, including outcomes after cortical-sparing adrenalectomy for bilateral adrenal disease. In addition, pathological features of malignancy, surveillance considerations, and the management of advanced disease are also discussed.

Surgical approach to patients with pheochromocytoma

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors that secrete excess catecholamines leading to secondary hypertension and cardiovascular morbidity. Once biochemical testing with either 24-hour urinary fractioned metanephrines or plasma free metanephrines confirms the diagnosis, patients are optimized with adequate hydration to maintain their intravascular volume and the appropriate antihypertensive medications are initiated for optimal blood pressure control. Genetic testing and imaging is performed to determine the extent of adrenalectomy and the optimal surgical approach. Surgical approaches include transabdominal or retroperitoneal minimally invasive approaches, and transabdominal open approaches. Factors that influence the surgical approach include germline genetic test results, the size of the tumor, body mass index, surgeon experience, and the likelihood of malignancy. The extent of adrenalectomy is based on germline genetic findings. Patients with syndromes such as von Hippel Lindau (VHL) or multiple endocrine neoplasia 2 (MEN 2) benefit from cortical-sparing adrenalectomy to avoid chronic steroid replacement and the risk of Addisonian crisis. Postoperative management includes hemodynamic monitoring and assessment for signs of hypoglycemia. Outcomes after surgery show improved blood pressure control in most patients and normalization of blood pressure in about a third of patients. Long-term follow-up is required for all patients to assess for recurrence.

Glucose Intolerance on Phaeochromocytoma and Paraganglioma-The Current Understanding and Clinical Perspectives

Half of the patients with phaeochromocytoma have glucose intolerance which could be life-threatening as well as causing postoperative hypoglycemia. Glucose intolerance is due to impaired insulin secretion and/or increased insulin resistance. Impaired insulin secretion is caused by stimulating adrenergic α2 receptors of pancreatic β-cells and increased insulin resistance is caused by stimulating adrenergic α1 and β3 receptors in adipocytes, α1 and β2 receptors of pancreatic α-cells and skeletal muscle. Furthermore, different affinities to respective adrenergic receptors exist between epinephrine and norepinephrine. Clinical studies revealed patients with phaeochromocytoma had impaired insulin secretion as well as increased insulin resistance. Furthermore, excess of epinephrine could affect glucose intolerance mainly by impaired insulin secretion and excess of norepinephrine could affect glucose intolerance mainly by increased insulin resistance. Glucose intolerance on paraganglioma could be caused by increased insulin resistance mainly considering paraganglioma produces more norepinephrine than epinephrine. To conclude, the difference of actions between excess of epinephrine and norepinephrine could lead to improve understanding and management of glucose intolerance on phaeochromocytoma.

Glycemic Disturbances in Pheochromocytoma and Paraganglioma

In this review article, we aimed to analyze the available data on pheochromocytomas and paragangliomas as it pertains to their not as well-recognized association with significant glycemic abnormalities in the preoperative, perioperative, and postoperative settings as well as how they should be managed clinically. Pheochromocytomas are rare adrenal tumors that account for about 0.1% of hypertension. Paragangliomas, on the other hand, are even less common and have fewer clinical manifestations. Both types of tumors may have unusual modes of presentation which can challenge even the most experienced clinicians and are easy to overlook, resulting in post-mortem diagnosis. We wish to draw further attention to the life-threatening effects on glucose and insulin homeostasis that can occur in the form of hyperglycemic and hypoglycemic states. Hyperglycemia is a result of a glucose intolerant state created in the setting of catecholamine excess, which can present in the form of resistant diabetes, diabetic ketoacidosis (DKA), or even hyperglycemic hyperosmolar states (HHS). In many reported cases, these abnormalities resolve with resection of the tumor. However, past clinicians have also described a state of "reactive hypoglycemia" that can occur following tumor resection, further emphasizing the need for very close perioperative and postoperative monitoring. Severe hypoglycemia may also occur with inherited diseases linked to pheochromocytoma such as von Hippel-Lindau (VHL) disease as well as predominantly epinephrine-producing tumors, given some of the dramatic downstream effects of alpha and beta adrenoceptor agonization. While much of the data remains anecdotal, clinicians will benefit from the awareness of the protean manifestations of these tumors and the varied and lesser-known effects on glucose and insulin homeostasis.

Somatostatin-secreting Pheochromocytoma Mimicking Insulin-dependent Diabetes Mellitus

We herein present the findings of a 42-year-old woman with either adrenal pheochromocytoma or intraadrenal paraganglioma that simultaneously secreted somatostatin, thus mimicking insulin-dependent diabetes mellitus. Pheochromocytoma was clinically diagnosed based on scintigraphy, elevated catecholamine levels, and finally a histopathological analysis of resected specimens. The patient had diabetic ketosis, requiring 40 U insulin for treatment. Following laparoscopic adrenalectomy, insulin therapy was discontinued and the urinary c-peptide levels changed from 5.5-9.0 to 81.3-87.0 μg/day. Histologically, somatostatin immunoreactivity was detected and the somatostatin levels were elevated in the serum-like fluid obtained from the tumor. Clinicians should be aware of the possible occurrence of simultaneous ectopic hormone secretion in patients with pheochromocytoma.

Incidental Phaeochromocytoma on Staging PET-CT in a Patient with a Sigmoid Tumour and Situs Inversalis Totalis

An adrenal “incidentaloma” is defined as an unexpected finding on radiological imaging performed for unrelated indications. Improvements in radiological technology have seen a dramatic increase in this phenomenon. We report the unique case of a 60-year-old female presenting with a 6-month history of abdominal pain, altered bowel habit, and rectal bleeding. Her past medical history included situs inversus totalis and a patent ductus arteriosus. Colonoscopy revealed an ulcerated tumour in her sigmoid colon. Staging PET-CT confirmed a sigmoid tumour and also identified a large heterogenous enhancing FDG-avid right adrenal mass. Biochemical testing/MIBG imaging confirmed a right adrenal phaeochromocytoma. Hypertension was controlled and excision was performed via a transperitoneal laparoscopic adrenalectomy, in the left lateral decubitus position. Uniquely, liver retraction was not required due to its position in the left hypochondrium. Histology confirmed a benign 46 mm phaeochromocytoma. Subsequent uncomplicated sigmoid colectomy/right salpingo-oophorectomy for a locally advanced colonic tumour was performed with adjuvant chemotherapy. This case highlights the importance of accurately identifying functioning adrenal tumours before elective surgery as undiagnosed phaeochromocytomas carry significant intraoperative morbidity/mortality. Right adrenalectomy was made easier in this patient by the liver's unique position. Uncomplicated colorectal resection was made possible by combined preoperative functional/anatomical imaging.

Diagnosis and management of pheochromocytoma: a practical guide to clinicians

Pheochromocytomas (PCCs) are rare catecholamine producing neuroendocrine tumors. The majority of these tumors (85 %) arise from the adrenal medulla. Those arising from the extra-adrenal neural ganglia are called paragangliomas (PGLs). Paroxysmal hypertension with sweating, headaches and palpitation are the usual presenting features of PCCs/ PGLs. Gene mutations are reported in 32-79 % of cases, making genetic screening mandatory in all the cases. The malignancy rates are 10-15 % for PCCs and 20-50 % for PGLs. Measurement of plasma or 24-hour urinary fractionated metanephrines is the best biochemical diagnostic test. Computed tomography or magnetic resonance imaging has high sensitivity (90-100 %) and reasonable specificity (70-90 %) for the anatomical localization. The functionality is assessed by different radionuclide imaging modalities such as metaiodobenzylguanidine (MIBG) scintigraphy, positron emission tomography or single photon emission computed tomography. The only modality of curative treatment is tumor excision. Proper peri-operative management improves the surgical outcomes. Annual follow up with clinical and biochemical assessment is recommended in all the cases after treatment. Children, pregnant women and older people have higher morbidity and mortality risk. De-bulking surgery, chemotherapy, radiotherapy, molecular agents like sunitinib and everolimus, radionuclide agents and different ablation procedures may be useful in the palliation of inoperable/metastatic disease. An update on the diagnostic evaluation and management of PCCs and PGLs is presented here.

Adrenergic crisis due to pheochromocytoma - practical aspects. A short review

Introduction

The definitive therapy in case of pheochromocytoma is complete surgical resection. Improper preoperative assessment and medical management generally places the patient at risk for complications, resulting from an adrenergic crisis. Therefore, it is crucial to adequately optimize these patients before surgery. Optimal preoperative medical management significantly decreases morbidity and mortality during the tumor resection.

Material and methods

This review addresses current knowledge in pre– and intraoperative assessment of a patient with pheochromocytoma.

Results

Before surgery the patient is conventionally prepared with α–adrenergic blockade (over 10–14 days) and subsequently, additional β–adrenergic blockade is required to treat any associated tachyarrhythmias. In preoperative assessment, it is obligatory to monitor arterial blood pressure, heart rate, and arrhythmias and to restore the blood volume to normal.

Conclusions

In conclusion, due to the pathophysiological complexity of a pheochromocytoma, the strict cooperation between the cardiologist, endocrinologist, surgeon and the anaesthesiologist for an uneventful outcome should be achieved in patients qualified for the surgical removal of such a tumor.

A case report of reactive hypoglycemia in a patient with pheochromocytoma and it's review of literature

Pheochromocytoma, a tumor characterized by catecholamine excess, is usually associated with impaired glucose tolerance. Hypoglycemia may occur after the abrupt withdrawal of catecholamines in the postoperative period. Rarely, insulin secretion by stimulation of β-2 adrenoreceptors may overwhelm the glucagon production, thereby causing hypoglycemia. Here, we describe a female with pheochromocytoma, who presented with postprandial hypoglycemia.

Pheochromocytoma: a review

Pheochromocytomas are catecholamine producing neuroendocrine tumors that can be adrenal or extra-adrenal in origin. The classic symptoms of pheochromocytoma are headache, palpitation, anxiety and diaphoresis and the tumor can occur at any age with equal gender distribution. In patients with an established mutation or hereditary syndrome the condition may manifest at a younger age than in those with sporadic disease. Pheochromocytoma can be associated with certain genetic syndromes such as multiple endocrine neoplasia type 2 (MEN 2), neurofibromatosis (NF) and von Hippel-Lindau (VHL) syndrome. Pheochromocytoma is diagnosed with biochemical confirmation of hormonal excess followed by anatomical localization (CT or MRI). The mainstay of definitive therapy is surgical resection. In this review, we discuss in detail about the symptomatology, diagnosis, genetic aspects and management of pheochromocytoma.

Fatal hypoglycemia in malignant pheochromocytoma: direct glucose consumption as suggested by (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography imaging

We present a patient with metastatic pheochromocytoma, who developed progressive and fatal hypoglycemia most likely secondary to direct tumor glucose consumption that did not respond to high-dose glucose infusion, corticosteroids, or glucagon therapy. The pattern of glucose uptake on (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography, with preferential tumor glucose uptake in association with a marked reduction in normal uptake in the heart, muscles, and brain, is highly suggestive of direct consumption of glucose by the tumor rather than insulin-like growth factor-2 mediated hypoglycemia. In patients with large-volume metastatic malignancies, direct tumor glucose consumption should be considered in the differential diagnosis of hypoglycemia. Nuclear medicine imaging techniques can illustrate the pathophysiology of hypoglycemia in such cases.

Pheochromocytoma: diagnostic and therapeutic update

Pheochromocytomas are catecholamine-secreting tumors that arise from chromaffin cells of the sympathetic nervous system. In 80-85% of cases, these tumors are located in the adrenal medulla while the remainder is located in extra-adrenal chromaffin tissues (paragangliomas). Pheochromocytomas account for 6.5% of incidentally discovered adrenal tumors. These tumors may be sporadic or the result of several genetic diseases: multiple endocrine neoplasia type 2, von Hippel-Lindau syndrome, neurofibromatosis type 1, and familial paraganglioma associated with mutations in succinate dehydrogenase subunits. Diagnosis of pheochromocytoma should first be established biochemically by measuring plasma free metanephrines and urinary fractionated metanephrines. The radiological imaging tests of choice are computed tomography (CT) or magnetic resonance imaging (MRI). The first-line specific functional imaging test is scintigraphy with (123)I-metaiodobenzylguanidine (MIBG); if this test is unavailable, scintigraphy with (131)I-MIBG is the second choice. Positron emission tomography (PET) with (18)F-F-fluorodopamine (F-DA) is useful in metastatic disease. The treatment of choice is laparoscopic surgery after adequate alpha adrenergic blockade. Approximately 10% of tumors are malignant. Chemotherapy is used for inoperable disease. Prognosis is good except in malignant disease, in which 5-year survival is less than 50%. The identification of the genes causing hereditary pheochromocytoma has led to changes in the recommendation for genetic testing.

Adverse drug reactions in patients with phaeochromocytoma: incidence, prevention and management

The dangers of phaeochromocytomas are mainly due to the capability of these neuroendocrine tumours to secrete large quantities of vasoactive catecholamines, thereby increasing blood pressure and causing other related adverse events or complications. Phaeochromocytomas are often missed, sometimes only becoming apparent during therapeutic interventions that provoke release or interfere with the disposition of catecholamines produced by the tumours. Because phaeochromocytomas are rare, evidence contraindicating use of specific drugs is largely anecdotal or based on case reports. The heterogeneous nature of the tumours also makes adverse reactions highly variable among patients. Some drugs, such as dopamine D(2) receptor antagonists (e.g. metoclopramide, veralipride) and beta-adrenergic receptor antagonists (beta-blockers) clearly carry high potential for adverse reactions, while others such as tricyclic antidepressants seem more inconsistent in producing complications. Other drugs capable of causing adverse reactions include monoamine oxidase inhibitors, sympathomimetics (e.g. ephedrine) and certain peptide and corticosteroid hormones (e.g. corticotropin, glucagon and glucocorticoids). Risks associated with contraindicated medications are easily minimised by adoption of appropriate safeguards (e.g. adrenoceptor blockade). Without such precautions, the state of cardiovascular vulnerability makes some drugs and manipulations employed during surgical anaesthesia particularly dangerous. Problems arise most often when drugs or therapeutic procedures are employed in patients in whom the tumour is not suspected. In such cases, it is extremely important for the clinician to recognise the possibility of an underlying catecholamine-producing tumour and to take the most appropriate steps to manage and treat adverse events and clinical complications.

[Hypoglycaemia after surgery on phaeochromocytoma]

Few cases of postoperative hypoglycaemia complicating the removal of a phaeochromocytoma have been reported in the literature. We reported one case of hypoglycaemia secondary to the removal of right phaeochromocytoma in a 30-year-old patient. Seven hours after the excision of the tumour, the patient developed a severe hypoglycaemia at 1.67 mmol x l(-1) revealed by seizures completely resolving in 24 h. The hypoglycaemia in this context resulted probably from the massive secretion of insulin by the beta cells of Langerhans islands due to the suppression of alpha-adrenergic inhibition. The prevention of this complication requires the repeated measurement of the capillary glycaemia in the postoperative period. An important supply of carbohydrate may be necessary to maintain a normoglycaemia.

Perioperative evaluation and management of the patient with endocrine dysfunction

Whenever possible, endocrine disorders should be identified and evaluated prior to surgery. A plan for perioperative management of diabetes should be based on the type of diabetes, what diabetes medications are taken, the status of diabetes control, and what type of surgery is planned. Perioperative management of diabetes must include bedside glucose monitoring. Patients with mild hypothyroidism can safely proceed with elective surgery. Elective surgery should be postponed for patients with moderate or severe hypothyroidism. Patients who have mild hyperthyroidism can undergo elective surgery with preoperative beta blockade. Elective surgery should not be done on patients with moderate or severe hyperthyroidism until they are euthyroid. Patients with pheochromocytoma need to be identified and properly treated before surgery to prevent perioperative cardiovascular complications. Patients who take endogenous steroids should have the status of their HPA axis determined prior to surgery. If the patient is undergoing moderate or major surgical stress and has documented or presumed HPA suppression, then stress doses of steroids should be give perioperatively.

Pheochromocytoma. Update on diagnosis, localization, and management

Pheochromocytoma, although rare, is associated with a high degree of morbidity and mortality if not recognized. A high degree of suspicion in patients with new-onset hypertension; hypertension with sudden worsening or development of diabetes mellitus; or a family history of MEN, neuroectodermal tumors, or simple pheochromocytoma should prompt biochemical confirmation with either 24-hour urine catecholamines (norepinephrine and epinephrine) or total MET (NMET plus MET). Following confirmation of the diagnosis, radiologic studies with CT and (if needed) MIBG are employed to localize the tumor. Surgical removal is the only definitive therapy. Medical management with alpha-blocking agents, to control symptoms and prevent a hypertensive crisis, is generally advocated for 2 weeks preoperatively and intraoperatively. Occasionally, beta-blockers, employed only after adequate alpha-blockade, are necessary to control tachycardia and tachyarrhythmias. High-dose MIBG and combination chemotherapy have been used adjunctively to treat malignant pheochromocytoma, although neither modality provides lasting satisfactory results. Normal urine assays performed 2 weeks postoperatively ensure the complete removal of all tumor. Additionally, lifelong follow-up (yearly initially) is necessary to detect any signs of benign recurrence or malignancy because these have been reported to occur as long as 41 years after the initial surgical resection. Biochemical evidence of excess catecholamine production usually precedes the clinical manifestations of catecholamine excess when these tumors recur.