Surveillance Improves Outcomes for Carriers of SDHB Pathogenic Variants: A Multicenter Study

CONTEXT

Carriers of succinate dehydrogenase type B (SDHB) pathogenic variants (PVs) are at risk of pheochromocytoma and paraganglioma (PPGL) from a young age. It is widely recommended carriers enter a surveillance program to detect tumors, but there are limited studies addressing outcomes of surveillance protocols for SDHB PV carriers.

OBJECTIVE

The purpose of this study was to describe surveillance-detected (s-d) tumors in SDHB PV carriers enrolled in a surveillance program and to compare their outcomes to probands.

METHODS

This was a multicenter study of SDHB PV carriers with at least 1 surveillance episode (clinical, biochemical, imaging) in Australian genetics clinics. Data were collected by both retrospective and ongoing prospective follow-up. Median duration of follow-up was 6.0 years.

RESULTS

181 SDHB PV carriers (33 probands and 148 nonprobands) were assessed. Tumors were detected in 20% of nonprobands undergoing surveillance (age range 9-76 years). Estimated 10-year metastasis-free survival was 66% for probands and 84% for nonprobands with s-d tumors (P = .027). S-d tumors were smaller than those in probands (median 27 mm vs 45 mm respectively, P = .001). Tumor size ≥40 mm was associated with progression to metastatic disease (OR 16.9, 95% CI 2.3-187.9, P = .001). Patients with s-d tumors had lower mortality compared to probands: 10-year overall survival was 79% for probands and 100% for nonprobands (P = .029).

CONCLUSION

SDHB carriers with s-d tumors had smaller tumors, reduced risk of metastatic disease, and lower mortality than probands. Our results suggest that SDHB PV carriers should undertake surveillance to improve clinical outcomes.

Risk stratification of indeterminate thyroid nodules using ultrasound and machine learning algorithms

BACKGROUND

Indeterminate thyroid nodules (Bethesda III) are challenging to characterize without diagnostic surgery. Auxiliary strategies including molecular analysis, machine learning models, and ultrasound grading with Thyroid Imaging, Reporting and Data System (TI-RADS) can help to triage accordingly, but further refinement is needed to prevent unnecessary surgeries and increase positive predictive values.

DESIGN

Retrospective review of 88 patients with Bethesda III nodules who had diagnostic surgery with final pathological diagnosis.

MEASUREMENTS

Each nodule was retrospectively scored through TI-RADS. Two deep learning models were tested, one previously developed and trained on another data set, mainly containing determinate cases and then validated on our data set while the other one trained and tested on our data set (indeterminate cases).

RESULTS

The mean TI-RADS score was 3 for benign and 4 for malignant nodules (p = .0022). Radiological high risk (TI-RADS 4,5) and low risk (TI-RADS 2,3) categories were established. The PPV for the high radiological risk category in those with >10 mm nodules was 85% (CI: 70%-93%). The NPV for low radiological risk in patients >60 years (mean age was 100% (CI: 83%-100%). The area under the curve (AUC) value of our novel classifier was 0.75 (CI: 0.62-0.84) and differed significantly from the chance-level (p < .00001).

CONCLUSIONS

Novel radiomic and radiologic strategies can be employed to assist with preoperative diagnosis of indeterminate thyroid nodules.

A contemporary clinical approach to genetic testing for heritable hyperparathyroidism syndromes

PURPOSE

The improved access and affordability of next generation sequencing has facilitated the clinical use of gene panel testing to test concurrently patients for multiple heritable hyperparathyroidism syndromes. However, there is little guidance as to which patients should be selected for gene panel testing and which genes should be included in such panels. In this review, we provide a practical approach to considering, interpreting and managing genetic testing for familial primary hyperparathyroidism (PHPT) syndromes and familial hypocalciuric hypercalcaemia (FHH) in patients with PTH-dependent hypercalcaemia. We discuss known genes implicated in PHPT and FHH, testing criteria and yields, pre-test counselling, laboratory considerations, and post-test management.

METHODS

In addition to reviewing the literature, we conducted audits of local genetic testing data to examine the real-world yield of genetic testing in patients with PTH-dependent hypercalcaemia.

RESULTS

Our local audits revealed a positive genetic testing rate of 15-26% in patients with suspected hyperparathyroidism syndromes.

CONCLUSION

Based on the particular testing criteria met, affected patients should be tested for variants in the genes currently implicated in PHPT (MEN1, CDC73, RET, CDKN1B, GCM2, CASR) and/or FHH (CASR, GNA11, AP2S1). Patients should be provided with pre- and post-test counselling, including consideration of potential implications for family members.

Immune Related Adverse Events of the Thyroid - A Narrative Review

Immune checkpoints are small molecules present on the cell surface of T-lymphocytes. They maintain self-tolerance and regulate the amplitude and duration of T-cell responses. Antagonism of immune checkpoints with monoclonal antibodies (immune checkpoint inhibitors) is a rapidly evolving field of anti-cancer immunotherapy and has become standard of care in management of many cancer subtypes. Immune checkpoint inhibition is an effective cancer treatment but can precipitate immune related adverse events (irAEs). Thyroid dysfunction is the most common endocrine irAE and can occur in up to 40% of treated patients. Both thyrotoxicosis and hypothyroidism occur. The clinical presentation and demographic associations of thyrotoxicosis compared to hypothyroidism suggest unique entities with different etiologies. Thyroid irAEs, particularly overt thyrotoxicosis, are associated with increased immune toxicity in other organ systems, but also with longer progression-free and overall survival. Polygenic risk scores using susceptibility loci associated with autoimmune thyroiditis predict development of checkpoint inhibitor associated irAEs, suggesting potentially shared mechanisms underpinning their development. Our review will provide an up-to-date summary of knowledge in the field of thyroid irAEs. Major focus will be directed toward pathogenesis (including genetic factors shared with autoimmune thyroid disease), demographic associations, clinical presentation and course, treatment, and the relationship with cancer outcomes.

Papillary thyroid microcarcinoma: Is active surveillance always enough?

The incidence of papillary thyroid carcinoma (PTC) has increased over recent decades. This apparent epidemic has been attributed to the overdiagnosis of small PTC ≤10 mm in diameter (papillary thyroid microcarcinoma [PTMC]) incidentally detected on imaging for unrelated presentations. Although most PTMCs follow an indolent disease course, there is a small but significant proportion of cases that display more biologically aggressive features such as early metastasis and lymph node involvement. Management of PTMC diagnosed preoperatively should be distinguished from managing those PTMCs incidentally discovered after thyroidectomy. Here, we will focus on the challenge of managing the preoperative patient. Current guidelines recommend against routine biopsy of nodules ≤10 mm, even if they display highly suspicious features on ultrasound; however, it is not known how to identify those PTMCs at higher risk of disease progression. In view of their good prognosis even without surgical resection, active surveillance has emerged as an alternative to operative management for low-risk PTMC without lymph node involvement or distant metastasis. This review aims to summarise active surveillance data for PTMC and identify clinical features that may differentiate the indolent majority from those PTMCs that exhibit early disease progression and metastasis.

Thyroid Immune-related Adverse Events Following Immune Checkpoint Inhibitor Treatment

CONTEXT

Thyroid dysfunction occurs commonly following immune checkpoint inhibition. The etiology of thyroid immune-related adverse events (irAEs) remains unclear and clinical presentation can be variable.

OBJECTIVE

This study sought to define thyroid irAEs following immune checkpoint inhibitor (ICI) treatment and describe their clinical and biochemical associations.

METHODS

We performed a retrospective cohort study of thyroid dysfunction in patients with melanoma undergoing cytotoxic T-lymphocyte antigen-4 (CTLA-4) and/or programmed cell death protein-1 (PD-1) based ICI treatment from November 1, 2009, to December 31, 2019. Thyroid function was measured at baseline and at regular intervals following the start of ICI treatment. Clinical and biochemical features were evaluated for associations with ICI-associated thyroid irAEs. The prevalence of thyroid autoantibodies and the effect of thyroid irAEs on survival were analyzed.

RESULTS

A total of 1246 patients were included with a median follow-up of 11.3 months. Five hundred and eighteen (42%) patients developed an ICI-associated thyroid irAE. Subclinical thyrotoxicosis (n = 234) was the most common thyroid irAE, followed by overt thyrotoxicosis (n = 154), subclinical hypothyroidism (n = 61), and overt hypothyroidism (n = 39). Onset of overt thyrotoxicosis occurred a median of 5 weeks (interquartile range [IQR] 2-8) after receipt of a first dose of ICI. Combination immunotherapy was strongly associated with development of overt thyrotoxicosis (odds ratio [OR] 10.8, 95% CI 4.51-25.6 vs CTLA-4 monotherapy; P < .001), as was female sex (OR 2.02, 95% CI 1.37-2.95; P < .001) and younger age (OR 0.83 per 10 years, 95% CI 0.72-0.95; P = .007). By comparison, median onset of overt hypothyroidism was 14 weeks (IQR 8-25). The frequency of overt hypothyroidism did not differ between different ICI types. The strongest associations for hypothyroidism were higher baseline thyroid-stimulating hormone (OR 2.33 per mIU/L, 95% CI 1.61-3.33; P < .001) and female sex (OR 3.31, 95% CI 1.67-6.56; P = .01). Overt thyrotoxicosis was associated with longer progression free survival (hazard ratio [HR] 0.68, 95% CI 0.49-0.94; P = .02) and overall survival (HR 0.57, 95% CI 0.39-0.84; P = .005). There was no association between hypothyroidism and cancer outcomes.

CONCLUSION

Thyroid irAEs are common and there are multiple distinct phenotypes. Different thyroid irAE subtypes have unique clinical and biochemical associations, suggesting potentially distinct etiologies for thyrotoxicosis and hypothyroidism arising in this context.

International consensus on initial screening and follow-up of asymptomatic SDHx mutation carriers

Approximately 20% of patients diagnosed with a phaeochromocytoma or paraganglioma carry a germline mutation in one of the succinate dehydrogenase (SDHx) genes (SDHA, SDHB, SDHC and SDHD), which encode the four subunits of the SDH enzyme. When a pathogenic SDHx mutation is identified in an affected patient, genetic counselling is proposed for first-degree relatives. Optimal initial evaluation and follow-up of people who are asymptomatic but might carry SDHx mutations have not yet been agreed. Thus, we established an international consensus algorithm of clinical, biochemical and imaging screening at diagnosis and during surveillance for both adults and children. An international panel of 29 experts from 12 countries was assembled, and the Delphi method was used to reach a consensus on 41 statements. This Consensus Statement covers a range of topics, including age of first genetic testing, appropriate biochemical and imaging tests for initial tumour screening and follow-up, screening for rare SDHx-related tumours and management of elderly people who have an SDHx mutation. This Consensus Statement focuses on the management of asymptomatic SDHx mutation carriers and provides clinicians with much-needed guidance. The standardization of practice will enable prospective studies in the near future.

The Sydney AFF Score: A Simple Tool to Distinguish Females Presenting With Atypical Femur Fractures Versus Typical Femur Fractures

Atypical femur fractures (AFF) are a rare but serious complication of long-term bisphosphonate use. Although clearly defined by ASBMR criteria, a proportion of patients with AFFs may go unrecognized and the use of qualitative fracture criteria may lead to uncertainty in AFF diagnosis, with significant therapeutic implications. A score that rapidly and accurately identifies AFFs among subtrochanteric femur fractures using quantitative, measurable parameters is needed. In a retrospective cohort of 110 female patients presenting with AFFs or typical femur fractures (TFFs), multiple logistic regression and decision tree analysis were used to develop the Sydney AFF score. This score, based on demographic and femoral geometry variables, uses three dichotomized independent predictors and adds one point for each: (age ≤80 years) + (femoral neck width <37 mm) + (lateral cortical width at lesser trochanter ≥5 mm), (score, 0 to 3). In an independent validation set of 53 female patients at a different centre in Sydney, a score ≥2 demonstrated 73.3% sensitivity and 69.6% specificity for AFF (area under the receiver-operating characteristic curve [AUC] 0.775, SE 0.063) and remained independently associated with AFF after adjustment for bisphosphonate use. The Sydney AFF score provides a quantitative means of flagging female patients with atraumatic femur fractures who have sustained an AFF as opposed to a TFF. This distinction has clear management implications and may augment current ASBMR diagnostic criteria. © 2021 American Society for Bone and Mineral Research (ASBMR).

Multikinase inhibitors in thyroid cancer: timing of targeted therapy

In the 9 years since the publication of our 2011 review of targeted treatment of thyroid cancer with multikinase inhibitors, much has changed in the landscape of this heterogeneous disease. New multikinase and selective inhibitor treatments for medullary thyroid cancer, radioiodine-refractory thyroid cancer and anaplastic thyroid cancer have completed trials and improved progression-free survival. Many physicians are concerned by dose-limiting adverse effects of these drugs and are wary to begin treatment in patients who are systemically well but have marked disease burden, which makes the timing of treatment initiation challenging. Published mechanistic data on tyrosine kinase inhibitors (TKIs) have helped guide our understanding of how to dose effectively with these drugs. A major goal in TKI therapy is to optimize inhibition of oncogenic kinase drivers while maintaining patient quality of life. Real-world data have now been published on how TKIs have fared outside the clinical trial environment. In this Review, we provide a summary of published data on the efficacy of TKIs in clinical practice, to provide clinicians with a more realistic view of how their patients will manage and respond to TKI therapy. Furthermore, we review the data on mechanisms of inhibition, outcomes and adverse effects of TKIs and provide an update on targeted treatment of thyroid cancer, focusing on optimizing the timing of treatment initiation.

Multiple Endocrine Tumors Associated with Germline MAX Mutations: Multiple Endocrine Neoplasia Type 5?

CONTEXT

Pathogenic germline MAX variants are associated with pheochromocytoma and paraganglioma (PPGL), pituitary neuroendocrine tumors and, possibly, other endocrine and nonendocrine tumors.

OBJECTIVE

To report 2 families with germline MAX variants, pheochromocytomas (PCs) and multiple other tumors.

METHODS

Clinical, genetic, immunohistochemical, and functional studies at University hospitals in Australia on 2 families with germline MAX variants undergoing usual clinical care. The main outcome measures were phenotyping; germline and tumor sequencing; immunohistochemistry of PC and other tumors; functional studies of MAX variants.

RESULTS

Family A has multiple individuals with PC (including bilateral and metastatic disease) and 2 children (to date, without PC) with neuroendocrine tumors (paravertebral ganglioneuroma and abdominal neuroblastoma, respectively). One individual has acromegaly; immunohistochemistry of PC tissue showed positive growth hormone-releasing hormone staining. Another individual with previously resected PCs has pituitary enlargement and elevated insulin-like growth factor (IGF-1). A germline MAX variant (c.200C>A, p.Ala67Asp) was identified in all individuals with PC and both children, with loss of heterozygosity in PC tissue. Immunohistochemistry showed loss of MAX staining in PCs and other neural crest tumors. In vitro studies confirmed the variant as loss of function. In Family B, the proband has bilateral and metastatic PC, prolactin-producing pituitary tumor, multigland parathyroid adenomas, chondrosarcoma, and multifocal pulmonary adenocarcinomas. A truncating germline MAX variant (c.22G>T, p.Glu8*) was identified.

CONCLUSION

Germline MAX mutations are associated with PCs, ganglioneuromas, neuroblastomas, pituitary neuroendocrine tumors, and, possibly, parathyroid adenomas, as well as nonendocrine tumors of chondrosarcoma and lung adenocarcinoma, suggesting MAX is a novel multiple endocrine neoplasia gene.

Prophylactic central lymph node dissection informs the decision of radioactive iodine ablation in papillary thyroid cancer

BACKGROUND

Prophylactic central lymph node dissection (CLND) in papillary thyroid cancer (PTC) is controversial. We aimed to investigate if prophylactic CLND aids risk stratification and contributes to the decision for postoperative RAI ablation.

METHODS

Patients undergoing thyroidectomy for PTC and prophylactic CLND were identified from an endocrine surgical unit database. Pathology reports where reviewed for number and size of lymph nodes and patients stratified by risk according to the ATA guidelines.

RESULTS

426 patients were identified with PTC ≤4 cm and prophylactic CLND. 96 patients (23%) had central lymph node metastasis (CLNM) that qualified them for the intermediate risk group. In 17 patients (4%), the CLNM data led to upgrading independently of other histopathological characteristics. Correcting for multiple variables, CLNM was an independent factor contributing to RAI treatment.

CONCLUSION

Prophylactic CLND provides information to aid the selection of RAI ablation independent of primary cancer histology for risk stratification in 4% of patients. This benefit should be carefully balanced with the risk of CLND and patient treatment choice when deciding on management of PTC ≤4 cm.

Molecular Markers Guiding Thyroid Cancer Management

The incidence of thyroid cancer is rapidly increasing, mostly due to the overdiagnosis and overtreatment of differentiated thyroid cancer (TC). The increasing use of potent preclinical models, high throughput molecular technologies, and gene expression microarrays have provided a deeper understanding of molecular characteristics in cancer. Hence, molecular markers have become a potent tool also in TC management to distinguish benign from malignant lesions, predict aggressive biology, prognosis, recurrence, as well as for identification of novel therapeutic targets. In differentiated TC, molecular markers are mainly used as an adjunct to guide management of indeterminate nodules on fine needle aspiration biopsies. In contrast, in advanced thyroid cancer, molecular markers enable targeted treatments of affected signalling pathways. Identification of the driver mutation of targetable kinases in advanced TC can select treatment with mutation targeted tyrosine kinase inhibitors (TKI) to slow growth and reverse adverse effects of the mutations, when traditional treatments fail. This review will outline the molecular landscape and discuss the impact of molecular markers on diagnosis, surveillance and treatment of differentiated, poorly differentiated and anaplastic follicular TC.

Osteoporosis in the age of COVID-19

As the world grapples with the crisis of COVID-19, established economies and healthcare systems have been brought to their knees. Tough decisions regarding redirection of resources away from the management of conditions deemed "nonessential" are being made. How can we balance urgent resourcing of our acute crisis while not abandoning the real need of patients with osteoporosis? This article offers a few practical solutions.

Congenital Hypoparathyroidism Associated With Elevated Circulating Nonfunctional Parathyroid Hormone Due to Novel PTH Mutation

CONTEXT

Familial hypoparathyroidism has a heterogeneous presentation where patients usually have low parathyroid hormone (PTH) levels due to impaired production or secretion. This contrasts with pseudohypoparathyroidism, in which PTH resistance is usually associated with an elevated serum PTH. High levels of circulating PTH can also be due to bioinactive PTH, which is difficult to distinguish from pseudohypoparathyroidism on biochemical grounds.

CASE DESCRIPTION

We report on 2 sisters from consanguineous parents who presented with tetany at birth and were diagnosed with congenital hypocalcemia. Serum PTH levels were normal for many years, but progressively increased in midadulthood to greater than 100x the upper limit of normal on multiple assays. Homozygosity mapping was performed on 1 sister that demonstrated loss of heterozygosity (LOH) around PTH. Sequencing revealed a previously unreported variant, c.94T>C, predicting a codon change of p.Ser32Pro that is biologically inactive.

CONCLUSIONS

This case report shows a previously unreported unusual biochemical phenotype of a rising PTH in the context of a novel PTH mutation. This expands the evolving genotypes associated with hypoparathyroidism without established gene mutations.

Aberrant Splicing of SDHC in Families With Unexplained Succinate Dehydrogenase-Deficient Paragangliomas

Context

Germline mutations in the succinate dehydrogenase genes (SDHA/B/C/D, SDHAF2-collectively, "SDHx") have been implicated in paraganglioma (PGL), renal cell carcinoma (RCC), gastrointestinal stromal tumor (GIST), and pituitary adenoma (PA). Negative SDHB tumor staining is indicative of SDH-deficient tumors, usually reflecting an underlying germline SDHx mutation. However, approximately 20% of individuals with SDH-deficient tumors lack an identifiable germline SDHx mutation.

Methods

We performed whole-exome sequencing (WES) of germline and tumor DNA followed by Sanger sequencing validation, transcriptome analysis, metabolomic studies, and haplotype analysis in 2 Italian-Australian families with SDH-deficient PGLs and various neoplasms, including RCC, GIST, and PA.

Results

Germline WES revealed a novel SDHC intronic variant, which had been missed during previous routine testing, in 4 affected siblings of the index family. Transcriptome analysis demonstrated aberrant SDHC splicing, with the retained intronic segment introducing a premature stop codon. WES of available tumors in this family showed chromosome 1 deletion with loss of wild-type SDHC in a PGL and a somatic gain-of-function KIT mutation in a GIST. The SDHC intronic variant identified was subsequently detected in the second family, with haplotype analysis indicating a founder effect.

Conclusions

This is the deepest intronic variant to be reported among the SDHx genes. Intronic variants beyond the limits of standard gene sequencing analysis should be considered in patients with SDH-deficient tumors but negative genetic test results.

Data set for the reporting of pheochromocytoma and paraganglioma: explanations and recommendations of the guidelines from the International Collaboration on Cancer Reporting

BACKGROUND AND OBJECTIVES

The International Collaboration on Cancer Reporting (ICCR) is a not-for-profit to develop evidence-based, internationally agreed-upon standardized data sets for each anatomic site, to be used throughout the world. Providing global standardization of pathology tumor classification, staging, and other reporting elements will lead to improved patient management and enhanced epidemiological research.

METHODS

Pheochromocytoma and paraganglioma are uncommon and are frequently overlooked in registry data sets. Malignant criteria have previously been defined only when there was metastatic disease.

RESULTS

With recent recognition of a significant inheritance association and the development of risk stratification tools, this data set was created in order to obtain more meaningful outcomes and management data, using similar criteria across the global pathology community. Issues related to key core and non-core elements, especially clinical hormonal status, familial history, tumor focality, proliferative fraction, adverse or risk stratification features, and ancillary techniques, are discussed in the context of daily application to these types of specimens.

CONCLUSIONS

The ICCR data set, developed by an international panel of endocrine organ specialists, establishes a pathology-standardized reporting guide for pheochromocytoma and paraganglioma.

Multiple endocrine neoplasia: an update

The multiple endocrine neoplasia (MEN) syndromes include MEN1, MEN2 (formerly MEN2A), MEN3 (formerly MEN2B) and the recently identified MEN4. Clinical presentations are varied and often relate to the overproduction of specific hormones. Understanding the genetics of each syndrome assists in determining screening timelines. Treatments for each manifestation are dependent on location, risk of recurrence or malignancy, hormone excess and surgical morbidity. Multidisciplinary management should include geneticists, genetic counsellors, endocrinologists and endocrine surgeons.

Malignant struma ovarii with a robust response to radioactive iodine

SUMMARY

Struma ovarii is a rare, usually benign ovarian tumour with malignancy occurring in <5% of cases. Metastases, particularly seeding to bone, are extremely rare. Presentation is variable but often features local pain and/or ascites and hyperthyroidism may occur. It is not established how to best treat and follow patients with extensive disease. Case reports of radioiodine (I131) ablative therapy following thyroidectomy have shown reduced recurrence. We describe the case of a 33-year-old woman who presented with bone pain and was diagnosed with skeletal metastases with features of follicular thyroid carcinoma. However, thyroid pathology was benign. She recalled that 5 years prior, an ovarian teratoma was excised, classified at that time as a dermoid cyst. Retrospective review of this pathology confirmed struma ovarii without obvious malignant features. The patient was found to have widespread metastases to bone and viscera and her thyroglobulin was >3000 µg/L following recombinant TSH administration prior to her first dose of I131. At 25 months following radioiodine treatment, she is in remission with an undetectable thyroglobulin and clear I131 surveillance scans. This case demonstrates an unusual presentation of malignant struma ovarii together with challenges of predicting metastatic disease, and demonstrates a successful radioiodine regimen inducing remission.

LEARNING POINTS

Malignant transformation of struma ovarii (MSO) is extremely rare and even rarer are metastatic deposits in bone and viscera. MSO can be difficult to predict by initial ovarian pathology, analogous to the difficulty in some cases of differentiating between follicular thyroid adenoma and carcinoma. No consensus exists on the management for post operative treatment of MSO; however, in this case, three doses of 6Gbq radioiodine therapy over a short time period eliminated metastases to viscera and bone. Patients should continue to have TSH suppression for ~5 years. Monitoring thyroglobulin levels can predict recurrence.

Checkpoint Inhibitor-Associated Autoimmune Diabetes Is Distinct From Type 1 Diabetes

CONTEXT

Checkpoint inhibitor-associated autoimmune diabetes mellitus (CIADM) is a rare illness, and little is known about its incidence, clinical features, or pathogenesis.

CASE SERIES DESCRIPTION

Consecutive patients from a single quaternary melanoma center who developed new-onset insulin-requiring diabetes after commencing anti-programmed cell death-1 (PD-1) immunotherapy were studied to describe CIADM characteristics. Ten (1.9%) of 538 patients with metastatic melanoma treated with anti-PD-1-based immunotherapy from March 2015 to March 2018 developed CIADM. Nine patients had no history of diabetes, and one had pre-existing type 2 diabetes mellitus. Median time from immunotherapy start to CIADM diagnosis was 25 weeks [interquartile range (IQR), 17.5 to 34.5 weeks]. All patients had normal serum C-peptide shortly before CIADM onset and an inappropriately low level when measured soon after. At CIADM diagnosis, median hemoglobin A1c was 7.6% (IQR, 7.15% to 9.75%), median glucose level was 32.5 mmol/L (IQR, 21.6 to 36.7 mmol/L), and median C-peptide concentration was 0.35 nmol/L (IQR, 0.10 to 0.49 mmol/L). Type 1 diabetes (T1D)-associated autoantibodies (DAAs) were present in two patients (both of whom had anti-glutamic acid decarboxylase antibody); all were negative for insulin-associated protein 2, insulin, and ZnT8. Three patients were heterozygous for an HLA class II T1D-risk haplotype; two additional patients also carried protective haplotypes for T1D. All patients continued immunotherapy; eight (80%) had complete or partial oncological response, and all patients required ongoing insulin therapy.

CONCLUSION

CIADM is characterized by sudden permanent β-cell failure occurring after immunotherapy. It is distinct from T1D, usually lacks DAA or T1D-associated HLA-risk haplotypes, and is associated with difficult glycemic control from the onset. As such, CIADM represents a new model of auto-inflammatory β-cell failure.

Metabolomics in the Diagnosis of Pheochromocytoma and Paraganglioma

Metabolomics refers to the detection and measurement of small molecules (metabolites) within biological systems, and is therefore a powerful tool for identifying dysfunctional cellular physiologies. For pheochromocytomas and paragangliomas (PPGLs), metabolomics has the potential to become a routine addition to histology and genomics for precise diagnostic evaluation. Initial metabolomic studies of ex vivo tumors confirmed, as expected, succinate accumulation in PPGLs associated with pathogenic variants in genes encoding succinate dehydrogenase subunits or their assembly factors (SDHx). Metabolomics has now shown utility in clarifying SDHx variants of uncertain significance, as well as the accurate diagnosis of PPGLs associated with fumarate hydratase (FH), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH2) and aspartate transaminase (GOT2). The emergence of metabolomics resembles the advent of genetic testing in this field, which began with single-gene discoveries in research laboratories but is now done by standardized massively parallel sequencing (targeted panel/exome/genome testing) in pathology laboratories governed by strict credentialing and governance requirements. In this setting, metabolomics is poised for rapid translation as it can utilize existing infrastructure, namely liquid chromatography-tandem mass spectrometry (LC-MS/MS), for the measurement of catecholamine metabolites. Metabolomics has also proven tractable to in vivo diagnosis of SDH-deficient PPGLs using magnetic resonance spectroscopy (MRS). The future of metabolomics - embedded as a diagnostic tool - will require adoption by pathologists to shepherd development of standardized assays and sample preparation, reference ranges, gold standards, and credentialing.

MiRNA-3653 Is a Potential Tissue Biomarker for Increased Metastatic Risk in Pancreatic Neuroendocrine Tumours

Pancreatic neuroendocrine tumours (PNETs) are relatively uncommon, accounting for 1-2% of all pancreatic neoplasms. Tumour grade (based on the Ki67 proliferative index and mitotic rate) is associated with metastatic risk across large cohorts; however, predicting the behaviour of individual tumours can be difficult. Therefore, any tool which could further stratify metastatic risk may be clinically beneficial. We sought to investigate microRNA (miRNA) expression as a marker of metastatic disease in PNETs. Tumours from 37 patients, comprising 23 with locoregional disease (L) and 14 with distant metastases (DM), underwent miRNA profiling. In total 506 miRNAs were differentially expressed between the L and DM groups, with four miRNAs (miR-3653 upregulated, and miR-4417, miR-574-3p and miR-664b-3p downregulated) showing statistical significance. A database search demonstrated that miRNA-3653 was associated with ATRX abnormalities. Mean survival between the two groups was correlated with mean expression of miRNA-3653; however, this did not reach statistical significance (p = 0.204). Although this is a small study, we conclude that miRNA-3653 upregulation may be associated with an increased risk of metastatic disease in PNETS, perhaps through interaction with ATRX and the alternate lengthening of telomeres pathway.