Parafibromin as a diagnostic instrument for parathyroid carcinoma-lone ranger or part of the posse?

Are Non-Coding RNAs Useful Biomarkers in Parathyroid Tumorigenesis?

Tumors of the parathyroid glands are common endocrine diseases almost always characterized by parathyroid hormone hypersecretion that determines the clinical manifestations of primary hyperparathyroidism, such as fatigue, kidney problems, weakness, brittle bones, and other symptoms. Most parathyroid neoplasia are benign adenomas, although rare malignant forms have been described. They are heterogeneous in terms of clinical presentation and the associated signs and symptoms overlap with those of disease and aging. Furthermore, most patients with hypercalcemia are discovered during routine blood tests for other reasons. Surgical removal is considered the main therapeutic option to cure these endocrine tumors and, therefore, innovative therapeutic approaches are actively required. Recently, a growing number of studies have suggested that alterations to the epigenetic mechanisms could play a pivotal role in parathyroid tumorigenesis. Most of the attention has been focused on non-coding RNAs (ncRNAs) (i.e., miRNAs, lncRNAs, and circRNAs) whose expression profile has been found to be deregulated in parathyroid tumors. The aim of the present paper is to give an insight into the ncRNAs involved in parathyroid tumorigenesis, which could be used in the future either as innovative diagnostic biomarkers or as therapeutic targets for the treatment of this endocrine neoplasia.

Prognostic role of parafibromin staining and CDC73 mutation in patients with parathyroid carcinoma: A systematic review and meta-analysis based on individual patient data

BACKGROUND AND OBJECTIVE

Parathyroid carcinoma (PC) is a rare malignant neoplasm with a relatively poor prognosis. The loss of parafibromin expression or the presence of CDC73 mutation has been found to be remarkably associated with malignancy in parathyroid tumours. However, the prognostic role of them in PC has not yet been shown due to sampling limitations. We conducted a systematic review and meta-analysis based on individual patient data to clarify the performance of parafibromin immunohistochemical staining and CDC73 gene sequencing in predicting outcomes for patients PC.

METHODS

Published studies from PubMed/MEDLINE, EMBASE, Cochrane and Scopus Databases were searched using the terms 'parafibromin', 'CDC73', 'HRPT2' and 'parathyroid' to identify eligible studies. From the included studies, the survival data of patients with PC were extracted, and a Cox proportional hazards model was used to assess hazard ratio (HR) for disease-free survival (DFS) and overall survival (OS).

RESULTS

A total of 193 patients from 9 studies were included in this survival analysis. Negative immunohistochemical staining of parafibromin was shown to be a risk factor for recurrence/metastasis (HR 2.73, P = .002) and death (HR 2.54, P = .004). Patient age ≥ 50 years was significantly related to lower OS (HR 2.37, P = .004) but not to DFS. CDC73 mutation was not statistically related to DFS or OS.

CONCLUSIONS

Negative parafibromin staining indicated a higher risk of recurrence/metastasis and mortality. The immunohistochemical staining of parafibromin seems to be more promising in predicting outcomes for patients with PC than the sequencing of CDC73.

Severe Primary Hyperparathyroidism Caused by Parathyroid Carcinoma in a 13-Year-Old Child; Novel Findings From HRpQCT

Primary hyperparathyroidism is a condition that occurs infrequently in children. Parathyroid carcinoma, as the underlying cause of hyperparathyroidism in this age group, is extraordinarily rare, with only a few cases reported in the literature. We present a 13-year-old boy with musculoskeletal pain who was found to have brown tumors from primary hyperparathyroidism caused by parafibromin-immunodeficient parathyroid carcinoma. Our patient had no clinical, biochemical, or radiographic evidence of pituitary adenomas, pancreatic tumors, thyroid tumors, pheochromocytoma, jaw tumors, renal abnormalities, or testicular lesions. Germline testing for AP2S1, CASR, CDC73/HRPT2, CDKN1B, GNA11, MEN1, PTH1R, RET, and the GCM2 gene showed no pathological variants, and a microarray of CDC73/HRPT2 did not reveal deletion or duplication. He was managed with i.v. fluids, calcitonin, pamidronate, and denosumab prior to surgery to stabilize hypercalcemia. After removal of a single parathyroid tumor, he developed severe hungry bone syndrome and required 3 weeks of continuous i.v. calcium infusion, in addition to oral calcium and activated vitamin D. Histopathological examination identified an angioinvasive parathyroid carcinoma with global loss of parafibromin (protein encoded by CDC73/HRPT2).HRpQCT and DXA studies were obtained prior to surgery and 18-months postsurgery. HRpQCT showed a resolution of osteolytic lesions combined with structural improvement of cortical porosity and an increase in both cortical thickness and density compared with levels prior to treatment. These findings highlight the added value of HRpQCT in primary hyperparathyroidism. In addition to our case, we have provided a review of the published cases of parathyroid cancer in children. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Parafibromin immunostainings of parathyroid tumors in clinical routine: a near-decade experience from a tertiary center

The cell division cycle 73 gene is mutated in familial and sporadic forms of primary hyperparathyroidism, and the corresponding protein product parafibromin has been proposed as an adjunct immunohistochemical marker for the identification of cell division cycle 73 mutations and parathyroid carcinoma. Here, we present data from our experiences using parafibromin immunohistochemistry in parathyroid tumors since the marker was implemented in clinical routine in 2010. A total of 2019 parathyroid adenomas, atypical adenomas, and carcinomas were diagnosed in our department, and parafibromin staining was ordered for 297 cases with an initial suspicion of malignant potential to avoid excessive numbers of false positives. The most common inclusion criteria for immunohistochemistry were marked tumor weight (146 cases) and/or fibrosis (77 cases) and/or marked pleomorphism (58 cases). In total, 238 cases were informatively stained, and partial or complete loss of nuclear parafibromin immunoreactivity was noted in 40 cases; 10 out of 182 adenomas (5%), 27 out of 46 atypical adenomas (59%), and 7 out of 10 carcinomas (70%), with positive and negative predictive values of 85 and 90%, respectively for the detection of atypical adenomas/carcinomas versus adenomas, and 18 and 98%, respectively for carcinomas versus atypical adenomas/adenomas. Male patients with high-proliferative tumors were overrepresented among cases with aberrant parafibromin immunohistochemistry, and carcinomas more frequently harbored parafibromin aberrancies than atypical adenomas and adenomas (p < 0.001). We conclude that parafibromin immunohistochemistry is a useful marker in the clinical routine when applied on a pre-selected material of cases, with positive immunoreactivity as a confident rule out marker of malignancy.

Updates on Immunohistochemical and Molecular Markers in Selected Head and Neck Diagnostic Problems

CONTEXT

- The head and neck regions have complex anatomic structures. They are not exempted from the rare occurrences of highly unusual, diagnostically challenging malignant neoplasms and mimickers.

OBJECTIVE

- To review and update the utility of immunohistochemistry and molecular biomarkers and to pursue diagnostic accuracy on selected rare neoplasms, especially some poorly differentiated malignancies.

DATA SOURCES

- Personal experience and information from the literature.

CONCLUSIONS

- Head and neck tumors include neoplasms originating from heterogeneous tissue. Using the selected clinical cases, this review illustrates a continuous development of emerging molecular-genetic techniques to assist in the interpretation of uncommon, often poorly differentiated, highly malignant neoplasms. The diagnostic results are appropriately transmitted to the oncologists, radiation oncologists, and surgeons to create a coordinated plan of care for patients with these unusual disorders affecting the head and neck.

Primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a common disorder in which parathyroid hormone (PTH) is excessively secreted from one or more of the four parathyroid glands. A single benign parathyroid adenoma is the cause in most people. However, multiglandular disease is not rare and is typically seen in familial PHPT syndromes. The genetics of PHPT is usually monoclonal when a single gland is involved and polyclonal when multiglandular disease is present. The genes that have been implicated in PHPT include proto-oncogenes and tumour-suppressor genes. Hypercalcaemia is the biochemical hallmark of PHPT. Usually, the concentration of PTH is frankly increased but can remain within the normal range, which is abnormal in the setting of hypercalcaemia. Normocalcaemic PHPT, a variant in which the serum calcium level is persistently normal but PTH levels are increased in the absence of an obvious inciting stimulus, is now recognized. The clinical presentation of PHPT varies from asymptomatic disease (seen in countries where biochemical screening is routine) to classic symptomatic disease in which renal and/or skeletal complications are observed. Management guidelines have recently been revised to help the clinician to decide on the merits of a parathyroidectomy or a non-surgical course. This Primer covers these areas with particular attention to the epidemiology, clinical presentations, genetics, evaluation and guidelines for the management of PHPT.

Evaluation of malignant parathyroid tumours in two European cohorts of patients with sporadic primary hyperparathyroidism

Purpose

Parathyroid carcinoma (PC) is remarkable for its rare occurrence and challenging diagnostics. PC accounts for 0.1–5 % cases of primary hyperparathyroidism (PHPT). The differentiation from benign tumours is difficult even by morphological criteria. To address these issues, we assessed the PC frequency in two separate European PHPT cohorts and evaluated the demographic, clinical, morphological and molecular background.

Methods

A retrospective study was carried out, using continuously maintained database (2005–2014) of PHPT patients from two tertiary referral university hospitals in Europe. The demographic, clinical data and frequency of PC among surgically treated PHPT was detected. Immunohistochemistry (IHC) was performed to detect parafibromin, representing protein product of HRPT2 gene and proliferation marker Ki-67.

Results

Both PHPT cohorts were characterised by close mean age values (58.6 and 58.0 years) and female predominance. The frequency of PC differed significantly between the cohorts: 2.1 vs. 0.3 %; p = 0.004. PC was characterised by invariable complete loss of parafibromin contrasting with parathyroid adenomas. The proliferation fraction was similar in both PC cohorts (10.6 and 11.0 %). PC showed significantly higher proliferation fraction than typical parathyroid adenomas (1.6 %), atypical adenomas (1.6 %) or adenomas featuring focal loss of parafibromin (2.2 %).

Conclusions

PC frequency can range significantly between the two European cohorts. The differences can be attributable to selection bias of patients referred for surgery and are not caused by discordant definition of malignant parathyroid histology. Diffuse loss of parafibromin and increased proliferation fraction by Ki-67 are valuable adjuncts in PC diagnostics due to significant differences with various clinical and morphological subtypes of adenoma.

Clinicopathological correlates of hyperparathyroidism

Hyperparathyroidism is a common endocrine disorder with potential complications on the skeletal, renal, neurocognitive and cardiovascular systems. While most cases (95%) occur sporadically, about 5% are associated with a hereditary syndrome: multiple endocrine neoplasia syndromes (MEN-1, MEN-2A, MEN-4), hyperparathyroidism-jaw tumour syndrome (HPT-JT), familial hypocalciuric hypercalcaemia (FHH-1, FHH-2, FHH-3), familial hypercalciuric hypercalcaemia, neonatal severe hyperparathyroidism and isolated familial hyperparathyroidism. Recently, molecular mechanisms underlying possible tumour suppressor genes (MEN1, CDC73/HRPT2, CDKIs, APC, SFRPs, GSK3β, RASSF1A, HIC1, RIZ1, WT1, CaSR, GNA11, AP2S1) and proto-oncogenes (CCND1/PRAD1, RET, ZFX, CTNNB1, EZH2) have been uncovered in the pathogenesis of hyperparathyroidism. While bi-allelic inactivation of CDC73/HRPT2 seems unique to parathyroid malignancy, aberrant activation of cyclin D1 and Wnt/β-catenin signalling has been reported in benign and malignant parathyroid tumours. Clinicopathological correlates of primary hyperparathyroidism include parathyroid adenoma (80-85%), hyperplasia (10-15%) and carcinoma (<1-5%). Secondary hyperparathyroidism generally presents with diffuse parathyroid hyperplasia, whereas tertiary hyperparathyroidism reflects the emergence of autonomous parathyroid hormone (PTH)-producing neoplasm(s) from secondary parathyroid hyperplasia. Surgical resection of abnormal parathyroid tissue remains the only curative treatment in primary hyperparathyroidism, and parathyroidectomy specimens are frequently encountered in this setting. Clinical and biochemical features, including intraoperative PTH levels, number, weight and size of the affected parathyroid gland(s), are crucial parameters to consider when rendering an accurate diagnosis of parathyroid proliferations. This review provides an update on the expanding knowledge of hyperparathyroidism and highlights the clinicopathological correlations of this prevalent disease.

Tumour nuclear oestrogen receptor beta 1 correlates inversely with parathyroid tumour weight

Primary hyperparathyroidism (PHPT) is a common endocrinopathy, frequently caused by a parathyroid adenoma, rarely by a parathyroid carcinoma that lacks effective oncological treatment. As the majority of cases are present in postmenopausal women, oestrogen signalling has been implicated in the tumourigenesis. Oestrogen receptor beta 1 (ERB1) and ERB2 have been recently identified in parathyroid adenomas, the former inducing genes coupled to tumour apoptosis. We applied immunohistochemistry and slide digitalisation to quantify nuclear ERB1 and ERB2 in 172 parathyroid adenomas, atypical adenomas and carcinomas, and ten normal parathyroid glands. All the normal parathyroid glands expressed ERB1 and ERB2. The majority of tumours expressed ERB1 (70.6%) at varying intensities, and ERB2 (96.5%) at strong intensities. Parathyroid carcinomas expressed ERB1 in three out of six cases and ERB2 in five out of six cases. The intensity of tumour nuclear ERB1 staining significantly correlated inversely with tumour weight (P=0.011), and patients whose tumours were classified as ERB1-negative had significantly greater tumour weight as well as higher serum calcium (P=0.002) and parathyroid hormone levels (P=0.003). Additionally, tumour nuclear ERB1 was not expressed differentially with respect to sex or age of the patient. Levels of tumour nuclear ERB2 did not correlate with clinical characteristics. In conclusion, decreased ERB1 immunoreactivity is associated with increased tumour weight in parathyroid adenomas. Given the previously reported correlation with tumour-suppressive signalling, selective oestrogen receptor modulation (SERMs) may play a role in the treatment of parathyroid carcinomas. Future studies of SERMs and oestrogen treatment in PHPT should consider tumour weight as a potential factor in pharmacological responsiveness.

CDC73 intragenic deletion in familial primary hyperparathyroidism associated with parathyroid carcinoma

CONTEXT

CDC73 mutations frequently underlie the hyperparathyroidism-jaw tumor syndrome, familial isolated hyperparathyroidism (FIHP), and parathyroid carcinoma. It has also been suggested that CDC73 deletion analysis should be performed in those patients without CDC73 mutations.

OBJECTIVE

To investigate for CDC73 deletion in a family with FIHP previously reported not to have CDC73 mutations.

PATIENTS AND METHODS

Eleven members (six affected with primary hyperparathyroidism and five unaffected) were ascertained from the family, and multiplex ligation-dependent probe amplification was performed to detect CDC73 deletion using leukocyte DNA.

RESULTS

A previously unreported deletion of CDC73 involving exons 1-10 was detected in five affected members and two unaffected members who were 26 and 39 years of age. Two affected members had parathyroid carcinomas at the ages of 18 and 32 years, and they had Ki-67 proliferation indices of 5 and 14.5% and did not express parafibromin, encoded by CDC73. Primary hyperparathyroidism in the other affected members was due to adenomas and atypical adenomas, and none had jaw tumors. Two affected members had thoracic aortic aneurysms, which in one member occurred with parathyroid carcinoma and renal cysts.

CONCLUSION

A previously unreported intragenic deletion of exons 1 to 10 of CDC73 was detected in a three-generation family with FIHP, due to adenomas, atypical adenomas, and parathyroid carcinomas. In addition, two affected males had thoracic aortic aneurysms, which may represent another associated clinical feature of this disorder.

Translational research in endocrine surgery

This article reviews translational research in endocrine surgery, with a focus on disorders of the thyroid, parathyroids, adrenals, and endocrine pancreas. Discovery of genes responsible for heritable endocrine cancer syndromes has increased knowledge of the causes and mechanisms of endocrine cancer and has refined surgical treatment options. Knowledge of mutations in sporadic cancer has led to rapid progress in small-molecule kinase inhibitor strategies. These breakthroughs and their influence on current therapy are discussed to provide surgeons with an overview of the basic science research currently creating new clinical treatments and improving patient care.

Diagnosis and management of parathyroid cancer

Parathyroid cancer is rare, but often fatal, as preoperative identification of malignancy against the backdrop of benign parathyroid disease is challenging. Advanced genetic, laboratory and imaging techniques can help to identify parathyroid cancer. In patients with clinically suspected parathyroid cancer, malignancy of any individual lesion is established by three criteria: demonstration of metastasis, specific ultrasonographic features, and a ratio >1 for the results of third-generation:second-generation parathyroid hormone assays. Positive findings for all three criteria dictate an oncological surgical approach, as appropriate radical surgery can achieve a cure. Mutation screening pinpoints associated conditions and asymptomatic carriers. Molecular profiling of tumour cells can identify high-risk features, such as differential expression of specific micro-RNAs and proteins, and germ line mutations in CDC73, but is unsuitable for preoperative assessment owing to the potential risks associated with biopsy. A validated, histopathology-based prognostic classification can identify patients in need of close follow-up and adjuvant therapy, and should prove valuable to stratify clinical trial cohorts: low-risk patients rarely die from parathyroid cancer, even on long-term follow-up, whereas 5-year mortality in high-risk patients is around 50%. This insight has improved the approach to parathyroid cancer by enabling risk-adapted surgery and follow-up.

Novel HRPT2/CDC73 gene mutations and loss of expression of parafibromin in Chinese patients with clinically sporadic parathyroid carcinomas

OBJECTIVE

It is widely recognized that the diagnosis of parathyroid carcinoma (PC) is often difficult because of the overlap of characteristics between malignant and benign parathyroid tumors, especially at an early stage. Based on the identification of tumor suppressor gene HRPT2/CDC73 and its association with hereditary and sporadic PC, screening of gene mutations and detection of parafibromin immunoreactivity have been suggested as diagnostic instruments of PC in Whites. There is little information about HRPT2/CDC73 mutations and its corresponding protein expression in patients with sporadic PC in Chinese population, and the long-term follow-up data is scarce.

METHODS

Paraffin-embedded tissues were obtained from 13 patients with PC, 13 patients with parathyroid adenoma (PA) and 7 patients with parathyroid hyperplasia(PH), and 6 normal parathyroid (NP) tissues as controls. Peripheral blood from 11 patients with PC was collected. PCR products using Genomic DNA extracted from tumor tissues or blood as template was sequenced for HRPT2/CDC73 gene. Expression of parafibromin in tumor tissues was evaluated by immunohistochemical analysis.

RESULTS

Six mutations in 6 of 13 patients with PC were identified, with three being novel. Four of them were germ-line mutations. Patients with mutations were susceptible to recurrence of the PC. Complete (8/13, 61.5%) or partial (5/13, 38.5%) loss of parafibromin expression was observed in PC tissues. All of tissue samples from normal parathyroid or benign parathyroid tumors displayed positive immunostaining of parafibromin except one adenoma.

CONCLUSIONS

The present study supplies information on the mutations and protein expression of HRPT2/CDC73 gene and phenotypes of parathyroid carcinoma in Chinese population. And the expanded mutation database of this gene may benefit patients in the diagnosis and treatment of this disease.

Molecular diagnosis of parathyroid carcinoma: a reality in the near future

INTRODUCTION

Parathyroid carcinoma (PC) is a rare endocrine malignancy that still suffers from a problem of delayed clinical diagnosis. Consequently, it usually is not recognized preoperatively and often is not conclusively identified during the operation either.

AREAS COVERED

The role played by parafibromin in the development of PC, representing an important advance in understanding the pathogenesis of this malignancy, is discussed. Through a careful search of the international literature, using "parathyroid carcinoma", "molecular genetics of parathyroid carcinoma" and "parathyroid tumorigenesis" as key words, other less mentioned molecular mechanisms are reappraised as potential molecular markers of PC; we also discuss their potential role in 20 parathyroid outgrowths. Finally, both the major efforts and the limitations of reported molecular diagnostic techniques and diagnostic markers are considered.

EXPERT OPINION

Currently, several critical issues still need to be addressed, such as the lack of: i) common criteria for the histopathological diagnosis of parathyroid malignancy and ii) timely appropriated preoperative diagnosis of PC. The latter issue would be of fundamental importance to assist the surgeon in performing a complete resection of all carcinomatous tissue at the time of the initial surgery, allowing for the greatest likelihood of a cure.

Molecular alterations in sporadic primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a frequent endocrine disorder characterized by an excessive autonomous production and release of parathyroid hormone (PTH) by the parathyroid glands. This endocrinopathy may result from the development of a benign lesion (adenoma or hyperplasia) or from a carcinoma. Most of the PHPT cases occur sporadically; however, approximately 10% of the patients present a familial form of the disease. The molecular mechanisms underlying the pathogenesis of sporadic PHPT are incompletely understood, even though somatic alterations in MEN1 gene and CCND1 protein overexpression are frequently observed. The MEN1 gene is mutated in about 30% of the parathyroid tumours and the protooncogene CCND1 is implicated in parathyroid neoplasia by rearrangements, leading to an overexpression of CCND1 protein in parathyroid cells. The aim of this work is to briefly update the molecular alterations underlying sporadic primary hyperparathyroidism.