Pheochromocytoma and Paraganglioma

A case of an unexpected posterior mediastinal functional paraganglioma: case report and literature review

Background

Paraganglioma can be found in a wide range of locations. However, paraganglioma in the posterior mediastinum is rare. An unexpected paraganglioma located in the posterior mediastinum was found during surgery. The anesthesia management of this patient was challenging.

Case presentation

A 65-year-old male with a posterior mediastinal tumor was scheduled for thoracoscopic mediastinal tumor resection. Severe hemodynamic changes during the operation and postoperative pathological diagnosis showed that the patient had a rare case of posterior mediastinal functional paraganglioma, which was not found before the operation. Although the patient did not experience side effects after surgery, he did experience a dangerous surgical process.

Conclusions

The correct diagnosis of paraganglioma, intensive preoperative screening, adequate preoperative preparation, and accurate intraoperative anesthesia management could provide better anesthesia for paraganglioma patients.

100-Year evolution of precision medicine and surgery for multiple endocrine neoplasia type 2A

PURPOSE

To determine whether published disease penetrance estimates of 50% for pheochromocytoma and 20-30% for primary hyperparathyroidism in multiple endocrine neoplasia (MEN 2A), conceivably reflecting overrepresentation of index patients with completely developed MEN 2A, may be too high.

METHODS

Cross-sectional study of carriers at high risk of MEN 2A from a tertiary referral center.

RESULTS

There were 213 carriers of RET mutations in codon 634, born between 1922 and 2014. Median age of thyroidectomy was 17 years, with MTC being present in 76.5%; pheochromocytoma in 31.0% at a median of 34 years in the first, and in 18.8% at a median of 35 years in the second adrenal; and primary hyperparathyroidism in 10.8% at a median of 39 years. MTC, pheochromocytoma and primary hyperparathyroidism, stratified by year of birth, were diagnosed earlier over time: for MTC from 51 to 4 years; for pheochromocytoma from 51 to 22.5 years in the first, and from 51 to 29.5 years in the second adrenal, and for primary hyperparathyroidism from 46 to 12 years (P ≤ 0.008). This decline in age was paralleled by diminishing tumor diameters, more strongly in the thyroid (from 20 to 1.8 mm; P < 0.001) than in the adrenals (from 43 to 30 mm in the first, and from 20-57.5 to 30.5 mm in the second adrenal; statistically nonsignificant).

CONCLUSIONS

The lower disease penetrance estimates and sluggish decline of adrenal tumor diameters call for more widespread adoption of adrenal-sparing and parathyroid preservation surgery based on early and regular biochemical screening.

Endocrine surgery during and after the COVID-19 epidemic: Expert guidelines from AFCE

The COVID-19 pandemic commands a major reorganisation of the entire French healthcare system. In France, general rules have been issued nationally and implemented by each healthcare centre, both public and private, throughout France. Guidelines drafted by an expert group led by the French-speaking Association of Endocrine Surgery (AFCE) propose specific surgical management principles for thyroid, parathyroid, endocrine pancreas and adrenal surgery during and after the COVID-19 epidemic.

[Endocrine surgery during and after the COVID-19 epidemic: Guidelines from AFCE]

La pandémie de COVID-19 impose une réorganisation majeure de l’ensemble de notre système de soins. En France, des règles générales ont été diffusées au niveau national et sont déclinées par chaque établissement, public comme privé, sur l’ensemble du territoire. Ces recommandations, rédigées par un groupe d’experts sous l’égide de l’Association francophone de chirurgie endocrinienne (AFCE), ont pour objectif de proposer des principes spécifiques de prise en charge chirurgicale au cours et au décours de l’épidémie de COVID- 19, pour les pathologies chirurgicales de la thyroïde, des parathyroïdes, du pancréas endocrine, et des surrénales.

Laparoscopic Resection of a Non-functional, Extra-adrenal Paraganglioma: A Case Report and Literature Review

Non-functional, extra-adrenal, retroperitoneal paraganglioma is a rare, neuroendocrine, and potentially malignant tumor. Its diagnosis and treatment may be challenging. A 69-year-old female patient was admitted because of a left para-aortic, solid, 4.4-cm mass, incidentally discovered during abdominal ultrasonography for screening purposes. Her clinical examination was unremarkable. Preoperative differential diagnosis based on cross-sectional imaging included tumor of neuroendocrine or mesenchymal origin. Hormonal investigation with 24-hour urinary catecholamines and metanephrines and plasma-fractionated metanephrines was in the normal range. Following consultation with the endocrinologist and anesthesiologist, the tumor was removed by using the three-dimensional (3D) laparoscopic transperitoneal surgical approach. The perioperative course was uneventful and the patient was discharged on the third postoperative day. Histopathologic findings were consistent with the diagnosis of retroperitoneal extra-adrenal paraganglioma of 5 cm in maximum diameter.

Anaesthetic management of a large paraganglioma resection in a woman with isolated L-looped transposition of the great arteries: a case report

BACKGROUND

Reports of anaesthetic management of paraganglioma resection in patients with isolated L-transposition of the great arteries (L-TGA) are rare. We focus on the preoperative evaluation, intraoperative management, and postoperative care of a frail patient with "physiologically corrected" L-TGA for paraganglioma resection.

CASE PRESENTATION

We performed general anaesthesia for a 46-year-old patient with "physiologically corrected" L-TGA undergoing open large retroperitoneal paraganglioma resection. Although the preoperative medical therapy had attained its goals, the patient went through three periods of severe episodic hypertension and tachycardia as tumour manipulation released catecholamines. Goal-directed fluid therapy based on pulse pressure variation (PPV) and point-of-care transesophageal echocardiography (TEE) imaging enabled anaesthesiologists to make rapid judgments and to regulate blood pressure in a timely manner, thereby reducing the risk of heart failure caused by massive rapid fluid bolus therapy. The patient was transferred to the intensive care unit because of intraoperative hemodynamic changes and significant blood loss. Despite transient myocardial injury (elevated troponin I), no lethal arrhythmia or complications occurred perioperatively, and the patient recovered well and was discharged 1 week later.

CONCLUSIONS

Goal-directed fluid therapy combined with the adoption of TEE could effectively guide fluid administration, which is helpful for anaesthesia management during operation. We recommend the routine use of TEE in such cases.

Pheochromocytoma and paraganglioma: An emerging cause of secondary osteoporosis

CONTEXT

Pheochromocytoma (PHEO) and paraganglioma (PGL) (PHEO and PGL: PPGLs) are catecholamine-producing neuroendocrine tumors, which are known to be associated with low bone mineral density (BMD). However, it remains unknown whether PPGLs are associated with high prevalence of osteoporotic fracture and if so, whether their surgical resection improves BMD has been addressed.

OBJECTIVE

To evaluate the risk of vertebral fracture (VF) in PPGLs and the improvement of BMD after surgery.

DESIGN AND SETTINGS

A retrospective cross-sectional study in a single referral center.

PARTICIPANTS

This study included the following patients: 1) 49 patients with PPGLs and 61 patients with non-functional AT who were examined radiograph of the spine, 2) 23 patients with PPGLs who were examined BMD at follow-up.

INTERVENTION

1) The prevalence of VF was evaluated between PPGLs and non-functional AT. 2) In PPGLs, BMD was evaluated at baseline and after surgery.

RESULTS

PPGLs had a higher prevalence of VF (43% [21/49]) than non-functional AT (16% [10/61]; p = 0.002). PPGLs were associated with VF after adjusting for age and sex (odds ratio, 4.47; 95% confidence interval, 1.76-11.3; p = 0.001). In PPGLs, BMD at the lumber spine was improved (before: 0.855 ± 0.198 g/cm², after: 0.888 ± 0.169 g/cm², mean of the difference: 0.032 g/cm², p = 0.026), with 3.8% increase.

CONCLUSION

This study demonstrates that PPGLs was associated with VF and that their surgical resection contributes to the improvement of BMD in the trabecular bone. These observations support the notion that PPGLs are an emerging cause of secondary osteoporosis.

Clinical features, complications, and outcomes of exogenous and endogenous catecholamine-triggered Takotsubo syndrome: A systematic review and meta-analysis of 156 published cases

Innumerable physical stress factors including externally administered catecholamines, and pheochromocytomas and paragangliomas (PPGLs) have been reported to trigger Takotsubo syndrome (TS). A systematic search of PubMed/MEDLINE identified 156 patients with catecholamine‐induced TS up to December 2017. Data were compared within the catecholamine‐induced TS cohort, but some comparisons were also done to a previously published large all‐TS cohort (n = 1750). The mean age was 46.4 ± 16.4 years (72.3% women). The clinical presentation was dramatic with high complication rates in (68.2%, n = 103; multiple complications 34.6%, n = 54). The most common TS ballooning pattern was apical or mid‐apical (45.2%, n = 69), followed by basal pattern (28.8%, n = 45), global pattern (16.0%, n = 25), mid‐ventricular (8.3%, n = 13), focal (0.6%, n = 1), and unidentified pattern (1.9%, n = 3). There was an increase in the prevalence of apical sparing ballooning pattern compared to all‐TS population (37.7% vs 18.3%, P < .00001). Higher complication rates were observed in TS with global ballooning pattern compared to apical ballooning pattern (23/25, 92% vs 38/65, 58.5%; P = .0022). Higher complication rates were observed in patients with age < 50 years than patients >50 years (73/92, 79.3% vs 29/56, 51.8%, P = 0.0009). Recurrence occurred exclusively in patients with PPGL‐induced TS (18/107 patients, 16.8%). PPGL‐induced TS was characterized by more global ballooning's pattern (22/104, 21.2% vs 3/49, 6.1%, P = 0.02), and lower left ventricular ejection fraction (25.54 ± 11.3 vs 31.82 ± 9.93, P = 0.0072) compared to exogenous catecholamine‐induced TS. In conclusion, catecholamine‐induced TS was characterized by a dramatic clinical presentation with extensive left ventricular dysfunction, and high complication rate.

A Comprehensive Analysis Identified the Key Differentially Expressed Circular Ribonucleic Acids and Methylation-Related Function in Pheochromocytomas and Paragangliomas

We investigated differentially expressed circular RNAs (circRNAs) and their potential functions in pheochromocytomas and paragangliomas (PCC/PGLs). Expression levels of circRNAs in tumor and adjacent normal tissues from seven PCC/PGL patients were analyzed through RNA sequencing. Real-time PCR was conducted to verify the key candidates identified in the sequencing data. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to predict the functions of these circRNAs. A total of 367 circRNAs were found differentially expressed between tumor and normal samples. The top three histone methylation-related circRNAs (hsa_circ_0000567, hsa_circ_0002897, and hsa_circ_0004473) and their target microRNAs (miRNAs) were identified and validated. We then mapped the circRNA-miRNA-messenger RNA (mRNA) coding-noncoding gene co-expression (CNC) networks to show the potential binding relationships between circRNAs and their targets in PCC/PGLs. The top five mRNAs, 88 miRNAs, and 132 circRNAs related to pathogenesis were utilized to map the CNC network, and we observed that the interactions of these candidates with their target miRNAs regulated histone methylation and further mediated PCC/PGL pathogenesis. This study is the first to provide the whole profile of differentially expressed circRNAs in PCC/PGLs. Our data indicate that altered circRNAs may control the pathogenesis of PCC/PGLs by regulating histone methylation processes, highlighting their role as potential biomarkers.

Bench-to-Bedside Theranostics in Nuclear Medicine

The optimum selection of the appropriate radiolabelled probe for the right target and the right patient is the foundation of theranostics in personalised medicine. In nuclear medicine, this process is realised through the appropriate choice of radiopharmaceuticals based on molecular biomarkers regarding molecular imaging. Theranostics is developing a strategy that can be used to implement accepted tools for individual molecular targeting, including diagnostics, and advances in genomic molecular knowledge, which has led to identifying theranostics biomaterials that have the potency to diagnose and treat malignancies. Today, numerous studies have reported on the discovery and execution of these radiotracers in personalised medicine. In this review, we presented our point of view of the most important theranostics agents that can be used to treat several types of malignancies. Molecular targeted radionuclide treatment methods based on theranostics are excellent paradigms of the relationship between molecular imaging and therapy that has been used to provide individualised or personalised patient care. Toward that end, a precise planned prospective examination of theranostics must be done to compare this approach to more standard therapies.

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

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

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

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

Histopathology of Parasellar Neoplasms

The anatomical and histological complexity of the parasellar region as well as the presence of embryonic remnants determine the huge diversity of parasellar neoplasms. Some of them are only located in the parasellar region, whereas others can occur elsewhere, within or outside the central nervous system. Their spectrum ranges from histologically benign and low-grade malignant to high-grade malignant tumours. Although rare, metastases can pose differential diagnostic dilemmas. The severity of the clinical picture, the challenges of surgery and the risk of adverse sequelae related to surgery or radiotherapy make parasellar tumours interesting entities for the clinicians irrespective of their histological malignancy grade. Due to the different cell origins of parasellar tumours, the World Health Organization classification system does not categorise them as a distinct group. Detailed criteria for classification and malignancy grading are presented in the classification systems covering central nervous system tumours, haematological malignancies and tumours of the soft tissue and bone. In the last few years, molecular genetic features have been integrated into the diagnosis of several types of the parasellar tumours enhancing diagnostic accuracy and providing information of the value for targeting therapies. In this review, we will present histopathological and molecular genetic features, updated classification criteria and recent advances in the diagnostics and rationale for novel pharmacological therapies of selected types of parasellar neoplasms.

Clinical Presentation and Treatment Outcomes of Children and Adolescents With Pheochromocytoma and Paraganglioma in a Single Center in Korea

PURPOSE

Pheochromocytoma (PCC) and paraganglioma (PGL) (PPGL) are rare neuroendocrine tumors, and data on managing these conditions in children and adolescents are lacking. The objective of this study was to demonstrate the clinical presentation and treatment outcomes in children and adolescents with PPGL in a single tertiary care center in Korea.

METHODS

This retrospective study included 23 patients diagnosed with PCC (n = 14) and PGL (n = 9) before the age of 21 at Samsung Medical Center (from June 1994 to June 2019). We describe age, gender, family history, clinical characteristics, laboratory findings, pathologic findings, therapeutic approaches, and treatment outcomes.

RESULTS

Of the 23 patients, 14 had PCC and nine had PGL. The median age at diagnosis was 16.8 years (range, 6.8-20.8 years). The common presenting symptoms were hypertension (n = 10), headache (n = 9), palpitation (n = 4), and sweating (n = 4). The plasma or 24-hour urine catecholamine and/or metabolite concentrations were markedly elevated in 22 patients with PPGL, but were normal in one patient with carotid body PGL. All tumors were visualized on computed tomography. Genetic tests were performed in 15 patients, and seven patients showed mutations in RET (n = 3), SDHB (n = 3), and VHL (n = 1). All patients underwent surgery, and complete excision was performed successfully. Three patients with metastasis underwent postoperative adjuvant therapy.

CONCLUSION

This study suggests that pediatric PPGL tends to be extra-adrenal and bilateral and shows a higher potential for genetic mutations. Considering the hereditary predisposition of pediatric PPGL, genetic screening tests are strongly recommended, and lifelong follow-up is needed to detect recurrence and metastasis. Further research with a larger sample size and routine genetic screening is needed to better understand the genetic conditions and long-term prognosis of PPGL.

Germline Mutation in KIF1Bβ Gene Associated with Loss of Heterozygosity: Usefulness of Next-Generation Sequencing in the Genetic Screening of Patients with Pheochromocytoma

The genetic approach of pheochromocytomas and paragangliomas has changed in the last two decades. Nowadays, we know that more than 40% of patients have a germline mutation in one of the susceptibility genes identified to date. Our aim is to underline how genetic diagnosis by next-generation sequencing (NGS) can improve the management of patients affected by pheochromocytomas and paragangliomas in our routine diagnostic screening. We reported a case presentation and next-generation sequencing analysis supported by in silico studies and evaluation of mitochondrial status in KIF1Bβ tissue. A 46-year-old male affected by a left secreting pheochromocytoma underwent surgery in 2017. After surgery, the normetanephrine levels decreased very slowly and a suspected abdominal lymph node was detected. We found a novel germline KIF1Bβ gene mutation, c.4052C > T, p. Pro1351Leu associated with tumor loss of heterozygosity, and resulted likely-pathogenetic by in silico studies. This mutation was also associated with an increased number of mitochondria through the electron microscopy compared with wild-type tissues as suggestive for mitochondria neoformation compensatory to the mitochondrial autophagic figures observed. Our results underline the usefulness of next-generation sequencing in the presence of multiple tumor predisposition genes and how, at the same time, its use may result challenging for the clinicians. To date, performing the genetic analysis according to the latest Consensus Statement is mandatory in patients affected by PHEO/PGL.

Preoperative Management of Pheochromocytoma and Paraganglioma

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors, characterized by excessive release of catecholamines (CAs), and manifested as the classic triad of headaches, palpitations, profuse sweating, and a variety of other signs and symptoms. The diagnosis of PPGL requires both evidence of excessive release of CAs and anatomical localization of CA-secreting tumor. Surgery is the mainstay of treatment for all patients with PPGL unless contraindicated. However, without proper preparation, the release of excessive CAs, especially during surgery, can result in lethal cardiovascular complications. Herein, we briefly reviewed the pathogenesis of this disease, discussed the current approaches and evidence available for preoperative management, summarizing the results of the latest studies which compared the efficacies of preoperative management with or without α adrenergic-receptor antagonists, aiming to facilitate better understanding of the preoperative management of PPGL for the physicians.

Temozolomide Is a Potential Therapeutic Tool for Patients With Metastatic Pheochromocytoma/Paraganglioma-Case Report and Review of the Literature

Context: Metastatic pheochromocytoma/paraganglioma (MPP) therapy mainly involves radionuclide therapy, chemotherapy, and targeted therapy. In recent years, temozolomide (TMZ) showed great promise in some MMP patients, especially those with SDHB germline mutation. We reported a patient with MPP who did not have any known germline genetic change and responded remarkably well to TMZ monotherapy. Case presentation: The patient was a 41-year-old woman with local and distant recurrence (soft tissues and bone metastases) of retroperitoneal paraganglioma. She suffered from dizziness, palpitation, sweating, weight loss and constipation, with the blood pressure fluctuating substantially from 130/100 mmHg to 190/120 mmHg, although she was on phenoxybenzamine and metoprolol medication. The patient showed clinical and radiological response after 3-cycle TMZ therapy. Upon 15 cycles of TMZ therapy, her symptoms were dramatically alleviated, urinary norepinephrine excretion decreased from 1,840 μg/24 h to 206 μg/24 h, and CT showed that the lesions further shrank. Molecular profiling of the tumor tissue of the patient revealed hypermethylation of the O6-methylguanine-DNA-methyltransferase (MGMT) promoter and a negative immunostaining for MGMT. Globally, only 26 cases of MPP treated with TMZ have been described so far. TMZ is effective, especially in patients with SDHB mutation, which can be explained by the silencing of MGMT expression as a consequence of MGMT promoter hypermethylation in SDHB-mutated tumors. Although, in general, patients with SDHB mutation or MGMT promoter hypermethylation have better response to TMZ, there are also exceptions. Severe side effects are uncommon, with only 17.4% patients experiencing Grade 3 toxicities, including lymphopenia, and hypertension. Conclusions: TMZ is effective and safe in MPP patients, and, it may work better on patients with SDHB-related MPP. Measurement of MGMT expression might help assess the tumor sensitivity to TMZ but this needs further systematic investigation.

Genetic and Clinical Profiles of Pheochromocytoma and Paraganglioma: A Single Center Study

Pheochromocytoma/paraganglioma (PPGL) has a high genetic heterogeneity with 40% germline variants in known pathogenic genes. Data in Chinese on this aspect are scanty. To detect the genetic and clinical profile of Chinese PPGL patients, we examined the variants of 12 known germline pathogenic genes (SDHA, SDHB, SDHC, SDHD, SDHAF2, FH, VHL, RET, NF1, MAX, TMEM127, and KIF1B) by next-generation sequencing and Sanger sequencing in 314 Chinese PPGL subjects. Twenty nine percent of Chinese PPGL patients had germline variants and SDHB was the most frequently mutated (14.6%). The most frequent SDHB variants were in exon 2, exon 7, and IVS 7. Pathogenic variants were more likely to occur in metastatic PPGL patients, paragangliomas, and patients under 30, with the ratio being 50.7% (35/69), 35.9% (56/156), and 49.5% (52/105), respectively. Our cohort included 314 patients from a single setting. The genetic and clinical features of Chinese PPGL patients were unique in some aspects compared to their non-Chinese counterparts. Identification of genotype-phenotype relation can serve as an effective tool for genetic prioritization and clinical decision-making.

Characteristic CT features of pheochromocytomas - probability model calculation tool based on a multicentric study

OBJECTIVES

The aim of the study was to evaluate the CT features of adrenal tumors in an effort to identify features specific to pheochromocytomas and second, to define a feasible probability calculation model.

METHODS

This multicentric retrospective study included patients from the period 2003 to 2017 with an appropriate CT examination and a histological diagnosis of an adrenal adenoma, pheochromocytoma, adrenocortical carcinoma, or metastasis. In total, 346 patients were suitable for the CT image analysis, which included evaluation of the largest diameter, the shape of the lesion, the presence of central necrosis and its margins, and the presence of an enhancing peripheral rim ("ring sign").

RESULTS

Pheochromocytomas have a significantly more spherical shape (P<0.001), whereas an elliptical shape significantly reduces the probability of a pheochromocytoma (odds ratio = 0.015), as does another shape (odds ratio = 0.006). A "ring sign" is also more frequent in pheochromocytomas compared to other adrenal tumors (P=0.001, odds ratio = 6.49). A sharp necrosis also increases the probability of a pheochromocytoma more than unsharp necrosis (odds ratio 231.6 vs. 20.2). The probability calculation model created on the basis of the results confirms a high sensitivity and specificity (80% and 95%).

CONCLUSION

This study confirms the value of anatomical features in the assessment of adrenal masses with the ability to significantly improve the identification of pheochromocytomas. Advanced assessment of the tumor shape was defined and a original comprehensive calculating tool of the pheochromocytoma probability was created on the basis of the results presented here and could be used in clinical routine.

Adrenocorticotropic Hormone-Producing Paraganglioma With Low Plasma ACTH Level: A Case Report and Review of the Literature

Ectopic adrenocorticotropic hormone (ACTH) syndrome caused by paraganglioma is extremely rare. It usually accompanied by high or normal plasma ACTH level. Here we described a male who presented with ectopic ACTH-producing paraganglioma and a low plasma ACTH level. Immunohistochemistry and immunofluorescence confirmed ACTH production in focal paraganglioma cells. This unusual case expanded the spectrum of ACTH-dependent Cushing's syndrome and revealed a potential mechanism of this unique clinical phenotype. Besides, the literature concerning ACTH-producing paraganglioma is reviewed.