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.

Morphological clues to the appropriate recognition of hereditary renal neoplasms.

An important emerging role of the surgical pathologist besides the traditional tasks of establishment of the diagnosis and documentation of prognostic and predictive factors, is to recognize the possibility of a hereditary condition in cases where the histology is suggestive for a familial cancer syndrome. In recent years, the knowledge regarding all of the above roles, including the role of recognition of familial cancer, has particularly expanded in renal neoplasms with the close scrutiny to morphology, molecular correlates and clinical features of the different sub-types of renal cell carcinoma. Awareness of these clinically distinctive sub-types and their associated histologic clues will prompt the pathologist for further immunohistochemical or molecular work up, to look for clinical information to support the suspected diagnosis of familial cancer, to alert managing physician/s to look for stigmata of history of familial cancer, which will permit triaging patients and their families for appropriate genetic counseling. This review provides a comprehensive review of the known sub-types of renal cell carcinoma that have a predilection to occur in the setting of hereditary disease; examples include renal cancers occurring in the background of von Hippel Lindau disease, hereditary leiomyomatosis and renal cell carcinoma syndrome, tuberous sclerosis, Birt Hogg Dube syndrome and succinate dehydrogenase deficiency. Herein we focus on diagnostic clues for renal tumors occurring in a non-pediatric setting that should prompt their correct recognition and reiterate the importance of the correct diagnosis.

[Disseminated osteolytic lesions in a 28-year-old refugee]. / Disseminierte osteolytische Läsionen bei einem 28-jährigen Flüchtling.

A 28-year-old Syrian refugee presented with right-sided knee pain and progressive deterioration of the general condition over the past months. Laboratory diagnostics revealed severe hypercalcemia due to primary hyperparathyroidism, and computed tomography (CT) scanning demonstrated disseminated osteolytic lesions throughout the skeleton. Histologically, these lesions were characterized by multinuclear giant cells (defining these lesions as so-called brown tumors). Finally, surgical removal of a jugular mass allowed the histopathologic diagnosis of a sporadic parathyroid carcinoma. In the patient, this condition was associated with a mutation in the HPRT2 gene locus.

[Clinical and morphological characteristics of parathyroid carcinoma]. / Kliniko-morfologicheskaia kharakteristika raka okoloshchitovidnoi zhelezy.

Parathyroid carcinoma (PTC) is a rare malignant tumor with the clinical manifestation of hyperparathyroidism, reliable morphological signs of invasive growth, and poor clinical prognosis. The differential diagnosis of PTC due to the rarity of this pathology, not always explicit morphological criteria, and the lack of a certain immunohistochemical panel is complex and needs further clarification. The paper summarizes an update on the clinical and morphological characteristics of PTC.

Update on parathyroid carcinoma.

INTRODUCTION: Parathyroid carcinoma (PC) is a rare endocrine disorder, commonly causing severe primary hyperparathyroidism (PHPT). PC is mainly a sporadic disease, but it may occur in familial PHPT. Patients with PC usually present markedly elevated serum calcium and PTH. The clinical features are mostly due to the effects of the excessive secretion of PTH rather than to the spread of tumor. At times, the diagnosis can be difficult. PURPOSE: The aim of this work is to review the available data on PC, and focus its molecular pathogenesis and the clinical utility of CDC73 genetic testing and immunostaining of its product, parafibromin. The pathological diagnosis of PC is restricted to lesions showing unequivocal growth into adjacent tissues or metastasis. Inactivating mutations of the cell division cycle 73 (CDC73) gene have been identified in up to 70 % of apparently sporadic PC and in one-third are germline. Loss of parafibromin immunostaining has been shown in most PC. The association of CDC73 mutations and loss of parafibromin predicts a worse clinical outcome and a lower overall 5- and 10-year survival. CONCLUSIONS: The treatment of choice is the en bloc resection of the tumor. The course of PC is variable; most patients have local recurrences or distant metastases and die from unmanageable hypercalcemia.

Transcriptional repression of tumor suppressor CDC73, encoding an RNA polymerase II interactor, by Wilms tumor 1 protein (WT1) promotes cell proliferation: implication for cancer therapeutics.

The Wilms tumor 1 gene (WT1) can either repress or induce the expression of genes. Inconsistent with its tumor suppressor role, elevated WT1 levels have been observed in leukemia and solid tumors. WT1 has also been suggested to act as an oncogene by inducing the expression of MYC and BCL-2. However, these are only the correlational studies, and no functional study has been performed to date. Consistent with its tumor suppressor role, CDC73 binds to RNA polymerase II as part of a PAF1 transcriptional regulatory complex and causes transcriptional repression of oncogenes MYC and CCND1. It also represses ß-catenin-mediated transcription. Based on the reduced level of CDC73 in oral squamous cell carcinoma (OSCC) samples in the absence of loss-of-heterozygosity, promoter methylation, and mutations, we speculated that an inhibitory transcription factor is regulating its expression. The bioinformatics analysis predicted WT1 as an inhibitory transcription factor to regulate the CDC73 level. Our results showed that overexpression of WT1 decreased CDC73 levels and promoted proliferation of OSCC cells. ChIP and EMSA results demonstrated binding of WT1 to the CDC73 promoter. The 5-azacytidine treatment of OSCC cells led to an up-regulation of WT1 with a concomitant down-regulation of CDC73, further suggesting regulation of CDC73 by WT1. Exogenous CDC73 attenuated the protumorigenic activity of WT1 by apoptosis induction. An inverse correlation between expression levels of CDC73 and WT1 was observed in OSCC samples. These observations indicated that WT1 functions as an oncogene by repressing the expression of CDC73 in OSCC. We suggest that targeting WT1 could be a therapeutic strategy for cancer, including OSCC.

A large extended family with hyperparathyroidism-jaw tumor syndrome due to deletion of the third exon of CDC73: clinical and molecular features.

PURPOSE: We described the phenotype of a large 4-generation family with Hyperparathyrodism-Jaw Tumor syndrome (HPT-JT) associated with a rare deletion of exon 3 of the CDC73 gene. METHODS: We collected medical, genetic data on 24 family members descended from a common ancestor carrying a heterozygous deletion of exon 3. RESULTS: Thirteen carried the deletion, the penetrance was estimated at 50% at 40 years. Seven patients (39 ± 14.5 years) presented with HPT which could start at 13. Median plasmatic calcium and PTH levels were 3.13 ± 0.7 mmol/L and 115 ± 406 pg/ml, respectively. Kidney disease related to hypercalcemia were present in 57.1% of patients. All seven patients underwent surgery to remove a single parathyroid adenoma. One recurrence occurred 7 years post-surgery. No parathyroid carcinoma has been found to date. We found two atypical parathyroid adenomas. We described an additional somatic variant in exon 1 of gene CDC73 in two tumors. Jaw tumors were not necessarily associated with hyperparathyroidism, as shown in one case. Two kidney cysts were also reported. Variable phenotype expressivity was emphasized by clinical presentations in 2 monozygotic twins: acute hypercalcemia, kidney failure and ossifying fibroma in one twin, versus normocalcemic parathyroid adenoma in the other one. CONCLUSION: We report a family carrier of a deletion of exon 3 of the CDC73 gene. This is characterized by a high level of hypercalcemia, deleterious kidney effects and atypical parathyroid adenomas without carcinomas. Onset and intensity of HPT remain unpredictable. The additional somatic mutation found in the parathyroid tumor could lead to these phenotypical variations.

Genotype of CDC73 germline mutation determines risk of parathyroid cancer.

Mutation of the CDC73 gene, which encodes parafibromin, has been linked with parathyroid cancer. However, no correlation between genotypes of germline CDC73 mutations and the risk of parathyroid cancer has been known. In this study, subjects with germline CDC73 mutations were identified from the participants of two clinical protocols at National Institutes of Health (Discovery Cohort) and from the literature (Validation Cohort). The relative risk of developing parathyroid cancer was analyzed as a function of CDC73 genotype, and the impact of representative mutations on structure of parafibromin was compared between genotype groups. A total of 419 subjects, 68 in Discovery Cohort and 351 in Validation Cohort, were included. In both cohorts, percentages of CDC73 germline mutations that predicted significant conformational disruption or loss of expression of parafibromin (referred as 'high-impact mutations') were significantly higher among the subjects with parathyroid cancers compared to all other subjects. The Kaplan-Meier analysis showed that high-impact mutations were associated with a 6.6-fold higher risk of parathyroid carcinoma compared to low-impact mutations, despite a similar risk of developing primary hyperparathyroidism between two groups. Disruption of the C-terminal domain (CTD) of parafibromin is directly involved in predisposition to parathyroid carcinoma, since only the mutations impacting this domain were associated with an increased risk of parathyroid carcinoma. Structural analysis revealed that a conserved surface structure in the CTD is universally disrupted by the mutations affecting this domain. In conclusion, high-impact germline CDC73 mutations were found to increase risk of parathyroid carcinoma by disrupting the CTD of parafibromin.

HEREDITARY ENDOCRINE TUMOURS: CURRENT STATE-OF-THE-ART AND RESEARCH OPPORTUNITIES: New and future perspectives for parathyroid carcinoma.

This report summarizes published data on parathyroid cancer, with the inclusion of topics discussed at MEN2019: 16th International Workshop on Multiple Endocrine Neoplasia, 27-29 March 2019, Houston, TX, USA. An expert panel on parathyroid cancer was constituted by the Steering Committee to address key questions in the field. The objectives were to recap open forum discussion of interested parties from multiple disciplines. The expert panel met in a closed session to consult on the data to be highlighted on the evidence-based results and on the future directions. Preceding the Conference, members of the expert panel conducted an extensive literature search. All presentations were based upon the best peer-reviewed information taking into account the historical and current literature. Questions were developed by the expert panel on parathyroid carcinoma. A comprehensive literature search for relevant studies was undertaken. This report represents the expert panel's synthesis of the conference material placed in a context designed to be relevant to clinicians and those engaged in cutting-edge studies of parathyroid carcinoma. This document not only provides a summary of our current knowledge but also places recent advances in its management into a context that should enhance future advances in our understanding of parathyroid carcinoma.

A Young Male with Parafibromin-Deficient Parathyroid Carcinoma Due to a Rare Germline HRPT2/CDC73 Mutation.

Hyperparathyroidism, commonly observed in asymptomatic middle-aged women, with mild hypercalcemia, is usually caused by a benign adenoma. Some cases present with more severe manifestation and greater hypercalcemia. Within this spectrum, several familial/genetic associations have been discovered. While the majority are caused by benign disease, adenomas, or hyperplasia, a small proportion (< 1%) are associated with malignant tumors and present with more severe symptoms. Although usually sporadic, recent reports document various gene mutations that strongly predispose to the development of parathyroid carcinoma. An increasing number of cases of hyperparathyroidism, benign or malignant, require and benefit from genetic analysis. We describe a 25-year-old male with hyperparathyroidism presenting with a pathological fracture, brown tumors, hypercalcemia, and markedly elevated parathyroid hormone levels. There was no family history of hyperparathyroidism or jaw tumors. Surgical removal revealed a single large tumor confirmed to be malignant. Immunohistochemical analysis revealed the absence of parafibromin and decreased APC (adenomatosis polyposis coli) expression. Genetic analysis revealed a rare germline nonsense mutation (R76X) in the parafibromin gene, HRPT2/CDC73. Parathyroid carcinoma should be suspected as a cause of hyperparathyroidism when clinical manifestations are severe, particularly in young individuals, < 59 years. Immunohistochemistry may lead to suspicion for a germline mutation as a significant contributor despite absence of a family history. The discovery of a germline mutation in parathyroid carcinoma alters the clinical management of the index case and that of family members. Long-term follow-up studies of such patients are necessary to develop evidence-based clinical guidelines.

Hyperparathyroidism-jaw Tumor Syndrome Confirmed by Preoperative Genetic Testing.

We herein report the case of a young woman who was diagnosed with primary hyperparathyroidism and in whom genetic testing confirmed a diagnosis of hyperparathyroidism-jaw tumor syndrome. Familial hyperparathyroidism was suspected based on the patient's young age at the onset of the disease. Thus, genetic testing was performed. It showed a germline mutation in the HRPT2/CDC73 gene and confirmed the diagnosis of hyperparathyroidism-jaw tumor syndrome. Total parathyroidectomy was performed to prevent recurrence. In patients with early-onset hyperparathyroidism, genetic testing should be considered to facilitate the selection of a proper surgical procedure based on the consideration of future life expectancy.

Osteoblast-specific deletion of Hrpt2/Cdc73 results in high bone mass and increased bone turnover.

Inactivating mutations that lead to loss of heterozygosity within the HRPT2/Cdc73 gene are directly linked to the development of primary hyperparathyroidism, parathyroid adenomas, and ossifying fibromas of the jaw (HPT-JT). The protein product of the Cdc73 gene, parafibromin, is a core member of the polymerase-associated factors (PAF) complex, which coordinates epigenetic modifiers and transcriptional machinery to control gene expression. We conditionally deleted Cdc73 within mesenchymal progenitors or within mature osteoblasts and osteocytes to determine the consequences of parafibromin loss within the mesenchymal lineage. Homozygous deletion of Cdc73 via the Dermo1-Cre driver resulted in embryos which lacked mesenchymal organ development of internal organs, including the heart and fetal liver. Immunohistochemical detection of cleaved caspase-3 revealed extensive apoptosis within the progenitor pools of developing organs. Unexpectedly, when Cdc73 was homozygously deleted within mature osteoblasts and osteocytes (via the Ocn-Cre driver), the mice had a normal life span but increased cortical and trabecular bone. OCN-Cre;Cdc73flox/flox bones displayed large cortical pores actively undergoing bone remodeling. Additionally the cortical bone of OCN-Cre;Cdc73flox/flox femurs contained osteocytes with marked amounts of cytoplasmic RNA and a high rate of apoptosis. Transcriptional analysis via RNA-seq within OCN-Cre;Cdc73flox/flox osteoblasts showed that loss of Cdc73 led to a derepression of osteoblast-specific genes, specifically those for collagen and other bone matrix proteins. These results aid in our understanding of the role parafibromin plays within transcriptional regulation, terminal differentiation, and bone homeostasis.

A Novel Mutation in a Patient with Hyperparathyroidism-Jaw Tumour Syndrome.

Hyperparathyroidism-jaw tumour syndrome (HPT-JT) is a rare variant of familial hyperparathyroidism, characterized by primary hyperparathyroidism (PHPT) due to one or multiple parathyroid adenomas, and benign tumours of the mandible and maxilla. It has an autosomal dominant pattern of inheritance, and is associated with mutations that deactivate the cell division cycle protein 73 homolog (CDC73) gene, also known as hyperparathyroidism 2 (HRPT2), located on the long arm of chromosome 1, that encodes for the tumour suppressor protein parafibromin. In the majority of cases, PHPT is the presenting symptom, but up to 30 % of HPT-JT cases initially present with an ossifying fibroma of the maxillofacial bones. HPT-JT may result in severe hypercalcemia-related complications and an elevated risk of parathyroid carcinoma. For this reason, early identification of the disease is important. We present the case of a 23-year-old woman who was found to have jaw tumours and was later diagnosed with PHPT. Genetic analysis revealed a novel mutation in exon 1 of CDC73. This report contributes to the understanding of the genetics of this rare syndrome. It also highlights the fact that HPT-JT should be considered and CDC73 mutation analysis should be performed in cases of early-onset PHPT associated with ossifying fibromas of the jaw.

Identification of a germline mutation in the HRPT2 gene in a Chinese family with parathyroid carcinomas.

This study reported a family with primary hyperparathyroidism due to parathyroid carcinoma and investigated the pathological and genetic features of family members. Three members of the family had clinical manifestation of primary hyperparathyroidism and tumors in the neck. All three patients underwent parathyroidectomy, thyroidectomy and level-VI neck dissection and were definitively diagnosed based on pathology. The index case was a patient that was found to have parathyroid carcinoma on the right side and parathyroid adenoma on the left side. The other two patients had local tumor recurrence and metastasis to distant organs. A germline mutation in the HRPT2 gene (Arg91Pro) was identified in all of the patients in this family. Study of the literature indicated that this is the first report of familial parathyroid carcinomas with an HRPT2 gene missense mutation. Results also indicated that HRPT2 may play an important role in the development of parathyroid carcinoma.

Detección inmunohistoquímica de parafibromina en patología de paratiroides / Immunohistochemical detection of parafibromin in parathyroid pathology

Introduction: The definitive diagnosis of parathyroid cancer is extremely difficult, from the clinical approach to the molecular diagnosis. A gene mutation was detected recently in patients with parathyroid cancer. It is a suppressor tumor gene called HRPT2, which codifies for a protein that participates in PAF1 complex, the parafibromin. It has been observed that the expression of this protein it's altered in parathyroid cancer, what would serve like method of diagnosis by immunohystochemistry, with a sensitivity and specificity of 73-96 percent and 99-100 percent respectively. Material and Method: The anti-parafibromin immunohysto-chemistry staining was made in 23 parathyroids tissue samples (5 adenomas, 6 hyperplasia, 7 normal and 5 carcinomas). Results: A positive pattern is observed in almost 100 percent of benign pathology and 100 percent in normal tissue. In the cases of carcinoma only 2 of 5 had a strong positivity. Conclusions: The pathological clinical correlation does not allow the association of the loss of parafibromin immunoreactivity in some unequivocal cases of parathyroid cancer. The parafibromin immunostaining does not allow to discriminate between benign or malign pathologies.

Introducción: El diagnóstico definitivo de cáncer de paratiroides es extremadamente difícil, desde el acercamiento clínico hasta el diagnóstico molecular. Se detectó recientemente en pacientes con cáncer de paratirodes un gen supresor de tumor mutado (HRPT2), que codifica para una proteína que participa en el complejo PAF1, la parafibromina. Se ha observado que la expresión de esta proteína está alterada en los casos de cáncer de paratiroides, lo que serviría como método de diagnóstico por inmunohistoquímica, con una sensibilidad y especificidad de 73-96 por ciento y 99-100 por ciento, respectivamente. Material y Método: Se realizó tinción inmunohistoquímica anti parafibromina en 23 muestras de tejido paratiroideo (5 adenomas, 6 hiper-plasias, 7 normales y 5 carcinomas). Resultados: Se observa un patrón positivo fuerte en casi 100 por ciento de la patología benigna y 100 por ciento en tejido normal. En los casos de carcinoma sólo 2 de 5 tenían positividad fuerte. Conclusiones: La correlación clínico patológica no permite asociar la pérdida de tinción de parafibromina en algunos casos de cáncer inequívocos. La tinción de parafibromina no permite discriminar entre patología benigna y maligna.

HRPT2-related familial isolated hyperparathyroidism: could molecular studies direct the surgical approach? / Formas familiares de hiperparatireoidismo relacionadas a mutações no gene HRPT2: estudos moleculares poderiam direcionar procedimentos cirúrgicos?

It is still debatable which is the best management to familial forms of hyperparathyroidism. Conservative, minimally invasive or aggressive surgical approaches have been proposed from different groups around the world. Our objective was to study the gene mutation, expression of HRPT2 and the clinical outcome after 32 years of follow-up in one Brazilian kindred with familial isolated hyperparathyroidism (FIHP). Clinical and biochemical data, direct sequencing of the HRPT2 gene, analysis of parafibromin expression using RT-PCR, and immunohistochemistry were done. A nonsense mutation was found in exon 1 (c.96G>A)(p.Trp32X) in all affected members studied. Using RT-PCR, mRNA transcription was altered with complete absence of both transcripts in tumor tissue. Immunohistochemical analysis of tumors showed loss of parafibromin immunoreactivity. In this kindred there was a high prevalence of recurrence (75 percent), or persistence after less than subtotal parathyroidectomy that led us to consider a more aggressive surgical approach should be discussed among the affected family members, once surgical criteria was met. We concluded that it is necessary to individualize the surgical approach for HRPT2-related hyperparathyroidism until we can gather a better phenotype-genotype correlation in larger series, to best define their treatment.

A melhor conduta nas formas familiares de hiperparatireoidismo relacionadas a mutações no gene HRPT2 ainda é controvertida. Cirurgias conservadoras, minimamente invasivas ou mais agressivas já foram propostas por diferentes grupos. Objetivamos estudar a seqüência e a expressão do gene HRPT2, além do desfecho clínico, após seguimento de até 32 anos de uma família brasileira com hiperparatireodismo familiar isolado (FIHP). Utilizamos dados clínicos e bioquímicos, seqüenciamento direto do HRPT2 além de análise da expressão da parafibromina através da RT-PCR e imunohistoquímica. Foi identificada mutação nonsense no éxon 1 (c.96G>A)(p.Trp32X) em todos os membros afetados que foram estudados. A análise do mRNA transcrito, através da RT-PCR, demonstrou ausência do transcrito no tecido tumoral. A imunohistoquímica também evidenciou ausência da parafibromina. Nessa família houve alta (75 por cento) prevalência de recorrência ou persistência da doença após paratireoidectomia parcial o que nos levou a considerar fundamental discutir uma abordagem cirúrgica mais agressiva com os outros familiares portadores da mutação caso critérios de indicação cirúrgica sejam atingidos. Dessa maneira, até que estudos mais amplos estabeleçam uma correlação genótipo-fenótipo no hiperparatireoidismo familiar relacionado a mutações no HRPT2, a abordagem cirúrgica deverá ser individualizada.