Looking beyond the thyroid: advances in the understanding of pheochromocytoma and hyperparathyroidism phenotypes in MEN2 and of non-MEN2 familial forms

Current prospects of hereditary adrenal tumors: towards better clinical management

Adrenocortical carcinoma (ACC) and pheochromocytoma/paraganglioma (PPGL) are two rare types of adrenal gland malignancies. Regarding hereditary tumors, some patients with ACC are associated with with Li-Fraumeni syndrome (LFS), and those with PPGL with multiple endocrine neoplasia type 2. Recent studies have expanded this spectrum to include other types of hereditary tumors, such as Lynch syndrome or familial adenomatous polyposis. Individuals harboring germline TP53 pathogenic variants that cause LFS have heterogeneous phenotypes depending on the respective variant type. As an example, R337H variant found in Brazilian is known as low penetrant. While 50-80% of pediatric ACC patients harbored a LFS, such a strong causal relationship is not observed in adult patients, which suggests different pathophysiologies between the two populations. As for PPGL, because multiple driver genes, such as succinate dehydrogenase (SDH)-related genes, RET, NF1, and VHL have been identified, universal multi-gene germline panel testing is warranted as a comprehensive and cost-effective approach. PPGL pathogenesis is divided into three molecular pathways (pseudohypoxia, Wnt signaling, and kinase signaling), and this classification is expected to result in personalized medicine based on genomic profiles. It remains unknown whether clinical characteristics differ between cases derived from genetic predisposition syndromes and sporadic cases, or whether the surveillance strategy should be changed depending on the genetic background or whether it should be uniform. Close cooperation among medical genomics experts, endocrinologists, oncologists, and early investigators is indispensable for improving the clinical management for multifaceted ACC and PPGL.

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.

Surgical Aspects of Primary Hyperparathyroidism

Parathyroidectomy (PTX) is the treatment of choice for symptomatic primary hyperparathyroidism (PHPT). It is also the treatment of choice in asymptomatic PHPT with evidence for target organ involvement. This review updates surgical aspects of PHPT and proposes the following definitions based on international expert consensus: selective PTX (and reasons for conversion to an extended procedure), bilateral neck exploration for non-localized or multigland disease, subtotal PTX, total PTX with immediate or delayed autotransplantation, and transcervical thymectomy and extended en bloc PTX for parathyroid carcinoma. The systematic literature reviews discussed covered (i) the use of intraoperative PTH (ioPTH) for localized single-gland disease and (ii) the management of low BMD after PTX. Updates based on prospective observational studies are presented concerning PTX for multigland disease and hereditary PHPT syndromes, histopathology, intraoperative adjuncts, localization techniques, perioperative management, "reoperative" surgery and volume/outcome data. Postoperative complications are few and uncommon (<3%) in centers performing over 40 PTXs per year. This review is the first global consensus about surgery in PHPT and reflects the current practice in leading endocrine surgery units worldwide. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Hereditary Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a commonly encountered clinical problem and occurs as part of an inherited disorder in ∼10% of patients. Several features may alert the clinician to the possibility of a hereditary PHPT disorder (eg, young age of disease onset) whilst establishing any relevant family history is essential to the clinical evaluation and will help inform the diagnosis. Genetic testing should be offered to patients at risk of a hereditary PHPT disorder, as this may improve management and allow the identification and investigation of other family members who may also be at risk of disease.

Multiple endocrine neoplasia type 2: A reveiw

Multiple endocrine neoplasias are rare hereditary syndromes some of them with malignant potential. Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant hereditary cancer syndrome due to germline variants in the REarranged during Transfection (RET) proto-oncogene. There are two distinct clinical entities: MEN 2A and MEN 2B. MEN 2A is associated with medullary thyroid carcinoma (MTC), phaeochromocytoma, primary hyperparathyroidism, cutaneous lichen amyloidosis and Hirschprung's disease and MEN 2B with MTC, phaeochromocytoma, ganglioneuromatosis of the aerodigestive tract, musculoskeletal and ophthalmologic abnormalities. Germline RET variants causing MEN 2 result in gain-of-function; since the discovery of the genetic variants a thorough search for genotype-phenotype associations began in order to understand the high variability both between families and within family members. These studies have successfully led to improved risk classification of prognosis in relation to the genotype, thus improving the management of the patients by thorough genetic counseling. The present review summarizes the recent developments in the knowledge of these hereditary syndromes as well as the impact on clinical management, including genetic counseling, of both individual patients and families. It furthermore points to future directions of research for better clarification of timing of treatments of the various manifestations of the syndromes in order to improve survival and morbidity in these patients.

Hereditary Parathyroid Disease: Sometimes Pathologists Do Not Know What They Are Missing

Parathyroid gland excision specimens are common and sometimes underestimated cases that many surgical pathologists encounter regularly. In the vast majority of cases, these will be spot diagnoses of sporadic primary parathyroid adenomas or, perhaps, hyperplasias commonly in the setting of renal failure. However, a small but significant number of parathyroid gland excisions may be due to heritable disease. In most cases, hereditary disease is suspected by the referring clinicians. Nevertheless, a subset of these are undetected which is significant, particularly in the setting of the multiple endocrine neoplasia (MEN), and the hyperparathyroidism jaw tumour (HPT-JT) syndromes. There have been recent advances in recognition of the morphological and immunohistochemical characteristics of these tumours and hyperplasias. While hereditary kindreds are over-represented at specialist referral centres, with awareness of the characteristic clinical and morphological features, the general surgical pathologist is frequently able to suggest the possibility of hereditary parathyroid disease. We therefore provide a succinct guide for pathologists to increase the recognition of hereditary parathyroid disease.

Diagnostic des phéochromocytomes et paragangliomes

Les phéochromocytomes et les paragangliomes sont des tumeurs rares responsables d’une surmorbidité et d’une surmortalité. Au cours de ces 20 dernières années, de nombreuses avancées ont permis de mieux les caractériser sur le plan phénotypique (via l’imagerie métabolique) et génotypique (avec la mise en évidence de nombreux gènes de prédisposition). La prise en charge d’un phéochromocytome ou d’un paragangliome nécessite désormais le recours à un centre expert dès la phase diagnostique. L’objectif de cette revue est de souligner les principales caractéristiques de ces tumeurs, et ce, afin de sensibiliser le clinicien aux différentes étapes permettant d’aboutir à une prise en charge optimale.

Differential expression of RET isoforms in normal thyroid tissues, papillary and medullary thyroid carcinomas

POURPOSES

We investigated the expression of RET9 and RET51 isoforms in medullary (MTC), papillary (PTC) thyroid carcinoma, normal thyroid tissues, and pheochromocytoma (PHEO) to verify if these isoforms are present also in follicular thyroid cell-derived tissues, and if there is a differential expression of RET9 and RET51 in MTC.

METHODS

Nineteen patients with MTC, 18 patients with PTC, 18 samples of contralateral normal thyroid tissues, and 5 cases of PHEO were included in this study. RET isoform expression was studied by real-time RT-PCR.

RESULTS

All MTCs and PHEOs were positive for RET9 and RET51. Fourteen/eighteen (77.7%) PTC cases were positive for RET9 and/or RET51, and four were positive for only one of the genes. In normal thyroid tissues, 3/18 (16.7%) cases were negative for both isoforms, 4/18 (22.2%) were positive for both, and 11/18 (61.1%) were positive for only one. RET isoforms were expressed at different levels in MTC, PHEO, PTC, and normal thyroid tissues: RET9 expression was higher in PHEO than in MTC, PTC, and normal thyroid tissues. RET9 expression was also higher in MTC than in PTC and normal thyroid tissues. No difference was observed between PTC and normal thyroid tissues. A similar pattern of expression was observed for RET51. In addition, RET51 was significantly more expressed than RET9 in MTC, while RET9 was the predominant isoform in PHEO.

CONCLUSIONS

Our study documented the expression of the RET9 and RET51 isoforms in normal thyroid and PTC tissues. RET9 and RET51 isoforms were also present in MTC and PHEO. RET51 expression was higher than RET9 expression in MTC, while there was no difference in the expression of these two isoforms in PTC and normal thyroid tissues. RET9 was more highly expressed than RET51 in PHEOs.

Management of familial hyperparathyroidism syndromes: MEN1, MEN2, MEN4, HPT-Jaw tumour, Familial isolated hyperparathyroidism, FHH, and neonatal severe hyperparathyroidism

While primary hyperparathyroidism (PHPT) generally represents a common endocrine disorder, being the more frequent cause of hypercalcemia in outpatients, familial forms of PHPT (FPHPT) account for no more than 2-5% of the overall PHPT. In the last decades, many technical progresses in both molecular and biochemical-radiological evaluation have been made, and substantial advancements in understanding these disorders have been reached. Differences both in the pathogenesis and clinical presentation exist among the various hyperparathyroid syndromic forms, and, since FPHPT is frequently associated to other endocrine, proliferative and/or functional disorders, as also non-endocrine tumours, with varying clinical spectrum of occurrence in each syndrome, its early clinically detection for appropriately preventing complications (i.e. kidney and bone disorders) is strictly advised. In this review, the clinical-biochemical features and diagnostic procedures of each FPHPT form will be summarized and a general overview on surgical and pharmacological approaches to FPHPT has been also considered.

Tumor characteristics and surgical outcome in incidentally discovered pheochromocytomas and paragangliomas

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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