Focus on parathyroid carcinoma

Imaging Recommendations for Diagnosis and Management of Primary Parathyroid Pathologies: A Comprehensive Review

Parathyroid pathologies are suspected based on the biochemical alterations and clinical manifestations, and the predominant roles of imaging in primary hyperparathyroidism are localisation of tumour within parathyroid glands, surgical planning, and to look for any ectopic parathyroid tissue in the setting of recurrent disease. This article provides a comprehensive review of embryology and anatomical variations of parathyroid glands and their clinical relevance, surgical anatomy of parathyroid glands, differentiation between multiglandular parathyroid disease, solitary adenoma, atypical parathyroid tumour, and parathyroid carcinoma. The roles, advantages and limitations of ultrasound, four-dimensional computed tomography (4DCT), radiolabelled technetium-99 (99mTc) sestamibi or dual tracer 99mTc pertechnetate and 99mTc-sestamibi with or without single photon emission computed tomography (SPECT) or SPECT/CT, dynamic enhanced magnetic resonance imaging (4DMRI), and fluoro-choline positron emission tomography (18F-FCH PET) or [11C] Methionine (11C -MET) PET in the management of parathyroid lesions have been extensively discussed in this article. The role of fluorodeoxyglucose PET (FDG-PET) has also been elucidated in this article. Management guidelines for parathyroid carcinoma proposed by the American Society of Clinical Oncology (ASCO) have also been described. An algorithm for management of parathyroid lesions has been provided at the end to serve as a quick reference guide for radiologists, clinicians and surgeons.

The clinicopathological features of lung metastases of parathyroid cancinoma

Parathyroid carcinoma(PC) is an extremely rare malignant tumor of the parathyroid glands. The lung is the most common target organ for PC distant metastases. In this study, twelve patients diagnosed with PC with lung metastases were enrolled in the study. Hematoxylin and Eosin(H&E) stained, immunohistochemical stained and next-generation sequencing (NGS) of a 425-gene panel were performed on tumor tissue samples. At the same time, we also evaluated its histopathologic characteristics. The results indicate that the microscopic examination of metastatic lesions reveals the same structure and characteristics as PC; the tumor was composed of relatively uniform cells organized in nests and separated by thin fibrous bands and abundant blood vessels. Immunohistochemical evaluation of Ki67, CyclinD1, PTH, SYN, CgA, and CD56 was useful in diagnosing PC with lung metastases. The most frequently genetic alterations were mutations of CDC73 and copy number variation (CNV) of MCL1, with a mutation rate of 25 %. In addition, the mutations of CDC73, ATM, TP53, ALK, ERBB2, MAP3K4, TSC1, CCND1 and CNV of CDK4, MCL1, SMARCB1 overlap between metastatic lesions and primary lesions. In conclusions, PC is a rare endocrine malignant tumor that is very difficult to diagnose preoperatively and prone to clinical recurrence or distant metastasis. Genetic mutations, presentation and histological characteristic were the basis for diagnosing PC with lung metastases.

Parathyroid carcinoma: Three case reports

BACKGROUND

Parathyroid carcinoma (PC) is a rare, slow-growing malignant tumor and a rare cause of primary hyperfunctioning of the parathyroid, with a highly variable clinical course, depending on the aggressiveness of the individual tumor and the degree of hypercalcemia.

CASE SUMMARY

The aim of this report is to summarize the diagnosis and treatment of three cases of PC and to review and conclude aspects regarding the three collected cases with reference to other relevant cases to explore the value of ultrasound in the diagnosis of PC. All three patients had hypercalcemia, consisting of a high serum calcium level and a high level of parathyroid hormone that was > 2-fold (even > 30-fold) of the normal upper limit. The ultrasonographic findings of the parathyroid gland showed that the glands were all > 30 mm, and the internal echo was uneven. All patients underwent surgery. PC in three cases was confirmed by routine histopathology and immunohistochemistry.

CONCLUSION

As clinical signs and laboratory results are nonspecific, it is difficult to diagnose PC preoperatively, so imaging examinations are often needed.

Parathyroid carcinoma: lessons from a rare malignancy of head and neck-a case series

Parathyroid carcinoma (PC) is a very rare head-neck malignancy. Because the symptoms of parathyroid carcinoma are similar to those of benign causes of hyperparathyroidism, it may be not easy to detect it before surgery. The management of PC after initial surgery will be perplexing because of the adequacy of surgery. We wish to describe the difficulties encountered throughout treatment using a literature review. We conducted a retrospective analysis of individuals with parathyroid carcinoma who had treatment at our department between 2017 and 2022. We gathered data on the clinical profile, investigations, management of hypercalcemia, surgical techniques, histopathological features, adjuvant therapy, and outcomes. We treated three patients with parathyroid carcinoma: Two patients with inferior parathyroid carcinoma and one with superior parathyroid carcinoma. Generalized weakness and bony pain are the predominant symptoms. In all cases, the tumor was located using 99Tc MIBI / SPECT scintigraphy and Ultrasonography. Hemithyroidectomy and tumor excision were done as the surgery of choice. All are disease-free at the 12th-month follow-up. We suggested that parathyroid hormone testing be performed in all bony fibrous lesions to rule out hyperparathyroidism. PC is a likely diagnosis when there is noticeable throat swelling, elevated PTH levels greater than 400 IU/L, and serum calcium levels greater than 15 mg/dL.

Parathyroid carcinoma: Single centre experience

OBJECTIVE

Parathyroid Carcinoma is a rare malignant neoplasm, accounting for less than 1% of primary hyperparathyroidism cases. Parathyroid carcinomas are characterized by markedly elevated levels of PTH, severe hypercalcemia and established target organ damage. The authors report the experience of a single centre regarding the management and outcome of patients with parathyroid carcinomas and revise relevant literature.

DESIGN

Retrospective review of all patients with parathyroid carcinoma evaluated at a tertiary oncologic centre from 1991 until 2021.

RESULTS

Seventeen patients were identified (10 males), with a mean age at diagnosis of 53 ± 16 years and a median follow-up of 16.5 years. Most patients presented with hypercalcemia (n = 15), with a mean serum calcium concentration of 13.5 mg/dl (9.6-16.5) and mean PTH of 1173 pg/ml (276-2500). Hyperparathyroidism-mediated organ damage was observed in most patients (n = 16), with predominant renal (n = 12) and skeletal (n = 9) complications. En bloc surgical resection was performed in nine patients. Three patients underwent adjuvant radiotherapy. Recurrence was observed in 8 cases (47.1%) after a median of 24 months following surgery and no independent predictors of recurrence were identified. The overall survival and disease specific survival at 5-year was 88% and 94%, respectively. CDC73 mutations were present in 38.5% of analysed patients and one patient was diagnosed with MEN1.

CONCLUSION

Parathyroid carcinoma is associated with a significant rate of recurrence and limited effective treatment beyond initial complete surgical resection. Therefore, preoperatively high index of suspicion is paramount to optimize patient care. This is, to our knowledge, the largest Portuguese cohort published so far.

Hyperparathyroidism Caused by Coexisting Parathyroid Hyperplasia and Unilateral Bifocal Parathyroid Carcinoma

ABSTRACT

The coexistence of parathyroid hyperplasia and carcinoma is uncommon. Here we report findings of 99mTc-sestamibi SPECT/CT study in a case of unilateral bifocal parathyroid carcinoma coexisting with parathyroid hyperplasia in a 49-year-old man. The images showed 4 foci of elevated activity around the thyroid. Histopathology confirmed the 2 lesions of the left side as parathyroid hyperplasia and the other 2 lesions of the right side as parathyroid carcinoma.

Near-Infrared Autofluorescence Features of Parathyroid Carcinoma

Introduction

Parathyroid carcinoma is very rare, and intraoperative definitive diagnosis can be elusive with currently available diagnostics. Near-infrared (NIR) autofluorescence is an emerging tool that identifies parathyroid glands in real time. It is not known whether NIR autofluorescence can detect parathyroid carcinoma intraoperatively.

Methods

Patients with preoperative suspicion for parathyroid carcinoma were identified from ongoing studies examining parathyroid autofluorescence with a NIR camera and probe. Specimens from these patients were examined intraoperatively to determine their autofluorescence patterns.

Results

Three patients with suspected parathyroid carcinoma were identified preoperatively. Intraoperative NIR autofluorescence imaging showed a relative lack of autofluorescence for all cases, in contrast to parathyroid adenomas and normal parathyroid glands, which typically exhibit significant autofluorescence. Final pathology confirmed parathyroid carcinoma in all cases.

Conclusion

Parathyroid carcinoma can be difficult to confirm prior to final pathology review. Our 3 cases suggest that absence of NIR autofluorescence may suggest the likelihood of parathyroid carcinoma, but more studies are needed to investigate this experience.

Tumor size rather than the thyroid invasion affects the prognosis of parathyroid carcinoma without lymph node or distant metastasis

PURPOSE

This study aimed to explore the prognostic value of thyroid invasion of parathyroid carcinoma without lymph node or distant metastasis.

METHODS

Two hundred and nine cases of parathyroid carcinoma from the SEER (1989-2014) were eligible for this study. A Chi-squared test, t test, X-tile, Kaplan-Meier curves, and multivariate Cox proportional hazard regression were used for analysis.

RESULTS

Thyroid invasion, sex, race, age, radiation, and surgery were not significantly associated with cancer-specific survival by multivariate analysis. However, tumor size ≥ 4 cm was significantly associated with worse cancer-specific survival (P < 0.001).

CONCLUSION

Thyroid invasion, which was the criterion for T₁ and T₂ staging criteria of parathyroid carcinoma according to the AJCC, did not affect the prognosis of patients with parathyroid carcinoma without local lymph node or distant metastasis. Our study indicates that a tumor size ≥ 4 cm may be an appropriate indicator of T₁ and T₂ cancer staging.

Management and Outcome of Parathyroid Carcinoma-Induced Primary Hyperparathyroidism: A Single-Centre Experience

BACKGROUND

Parathyroid carcinoma (PC) is the rarest endocrine cancer and an infrequent cause of primary hyperparathyroidism (PHPT), responsible for less than 1% of cases. Due to its rarity, treatment is challenging.

METHODS

A retrospective cohort study on 462 patients referred for parathyroidectomy to Thyroid and Parathyroid Unit at Santi Paolo e Carlo Hospital, Milan, Italy, from 2011 to 2021. We identified and individually described the patients affected with PC. Then, we split all patients treated for PHPT into four groups based on the cause: PC, adenoma, atypical adenoma, and hyperplasia. Patients' demographics, preoperative evaluation results, intraoperative findings, and outcomes for the PC group were compared with groups of PHPT due to benign causes.

RESULTS

Eight cases of PC were identified, five males and three females. Seven cases presented with symptoms of hypercalcemia and one with a neck mass. Five underwent en bloc resections and three local excisions. Histopathological features showed capsular invasion in four patients, capsular and soft tissue invasion in three patients, and vascular invasion in one case. No patients had distant metastasis. One patient was classed as high risk based on the Schulte classification system. All patients treated for PC were alive and disease-free at a mean follow-up of 38.4 months. When compared with other PHPT patients, PC patients were more frequently male and had higher preoperative blood calcium and PTH and lower phosphate levels, larger and heavier parathyroids excised, lower postoperative calcium, and a higher rate of postoperative hypoparathyroidism.

CONCLUSION

Our study highlights some aspects valuable to suspect PC and differentiate PHPT-PC from benign causes of PHPT preoperatively. Preoperative suspicion of malignancy is essential to guarantee the best course of treatment for patients. Although limited for size and follow-up, the excellent outcome of our series seems to support the value of both surgery extension and risk class according to the Schulte classification as possible prognostic factors for recurrence.

Giant Parathyroid Adenoma versus Parathyroid Carcinoma: Differentiating Two Entities

Giant parathyroid adenoma (GPA) is defined as adenoma larger than 3.5 g. Twenty-one cases of parathyroid mass >3.5 g in patients with primary hyperparathyroidism who underwent parathyroidectomy in Hospital Putrajaya, Malaysia were identified. Most cases presented with nephrolithiasis. Two cases are reported as parathyroid cancer. GPA has significantly higher serum calcium and iPTH levels and can be asymptomatic. Parathyroid carcinoma patients are frequently symptomatic, with large tumors. Differentiating GPA from parathyroid cancer is important as it determines the subsequent surgical intervention.

Expression profile of serum-related exosomal miRNAs from parathyroid tumor

OBJECTIVE

The expression pattern of exosomal miRNAs derived from parathyroid tumor is still unknown. In the present work, we aimed to examine the differences on microRNA (miRNA) expression, present in serum exosomes, by comparing parathyroid carcinoma (PC) and parathyroid adenoma (PA).

METHODS

MiRNA expression profile of serum exosomes, derived from 4 PC patients and 4 PA patients, were analyzed by next-generation sequencing technology. The differential expressions of target miRNAs were further verified in both serum exosomes and tissues of PC/PA patients by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Lastly, receiver operating characteristic (ROC) curves were plotted to investigate the efficiency of target exosomal miRNAs in distinguishing PC patients from PA controls.

RESULTS

Multiple differentially expressed miRNAs of serum exosomes were screened out by sequencing. Based on this screening, hsa-miR-146b-5p (p = 0.0846), hsa-miR-27a-5p (p = 0.0412), hsa-miR-93-5p (p = 0.73), hsa-miR-381-3p (p = 0.1239) and hsa-miR-134-5p (p = 0.0694) were upregulated in the serum exosomes of PC patients. These results were validated by qPCR, where the trend on differential miRNA expression was consistent with the sequencing results. Specifically, the expression of exosomal hsa-miR-27a-5p was able to clearly distinguish PC patients from PA controls, and related analysis indicated that the area under the ROC curve was 0.8594 (p = 0.0157).

CONCLUSIONS

Here we present, for the first time, the miRNA expression profile of serum exosomes derived from PC patients. Based on this result, we presently suggest that the exosomal hsa-miR-27a-5p may serve as a putative tumor marker for preoperative identification of PC and PA subjects.

A Case of Parathyroid Adenocarcinoma and Hyperparathyroidism, When "CRAB" Symptoms Are Not due to a Plasma Cell Myeloma

A previously well 49-year-old patient presented to our hospital with symptomatic hypercalcaemia complaining of polyuria and polydipsia, as well as abdominal and lower back pain (serum/ionized calcium at 3.66 milli mole/l and 1.90 milli moles/l). At admission, he had a normocytic anemia (Hb, 99 g/L) and acute kidney injury (creatinine at 161 μM). His parathyroid hormone (PTH) levels were at 67.6 pico moles/l. A plain X-ray of the lumbar spine showed the presence of a lytic lesion in the L4 vertebrae. CT and MRI confirmed this to be a destructive lesion. A subsequent pan CT scan showed a 2.8 cm complex nodule in the left lobe of the thyroid posteriorly. Excisional biopsy of the resected mass was associated with an infiltrative cellular parathyroid neoplasm with solid and nested architectural growth pattern admixed with hemorrhage and focal calcifications. The tumor showed lymphovascular and perineural invasion. At the time of workup and despite the absence of a positive SPEP/UPEP, a bone marrow biopsy was requested to rule out multiple myeloma. His normocellular bone marrow biopsy showed marked paratrabecular fibrosis and extensive bony remodelling but no metastatic invasion. The diagnosis of a metastatic parathyroid carcinoma was made. He is subsequently considered for palliative radiotherapy to the primary tumor bed and the lumbar spine. In addition, a role for immunotherapy with ipilimumab and nivolumab in context of clinical trials is envisioned and he is being considered for enrollment.

Clinical Presentation, Treatment, and Outcome of Parathyroid Carcinoma: Results of the NEKAR Retrospective International Multicenter Study

OBJECTIVE

In this retrospective cohort study, we describe the clinical presentation and workup of parathyroid carcinoma (PC) and determine its clinical prognostic parameters. Primary outcome was recurrence free survival.

SUMMARY BACKGROUND DATA

PC is an orphan malignancy for which diagnostic workup and treatment is not established.

METHODS

Eighty-three patients were diagnosed with PC between 1986 and 2018. Disease-specific and recurrence-free survivals were estimated with the Kaplan-Meier method. Risk factors for recurrence were identified by binary logistic regression with adjustment for age and sex. Thirty-nine tumors underwent central histopathological review.

RESULTS

Renal (39.8%), gastrointestinal (24.1%), bone (22.9%), and psychiatric (19.3%) symptoms were the most common symptoms. Surgical treatment was heterogeneous [parathyroidectomy [PTx)] alone: 22.9%; PTx and hemithyroidectomy: 24.1%; en bloc resection 15.7%; others 37.3%] and complications of surgery were frequent (recurrent laryngeal nerve palsy 25.3%; hypoparathyroidism 6%). Recurrence of PC was observed in 32 of 83 cases. In univariate analysis, rate of recurrence was reduced when extended initial surgery had been performed (P = 0.04). In multivariate analysis low T status [odds ratio (OR) = 2.65, 95% confidence interval (CI) 1.02-6.88, P = 0.045], N0 stage at initial diagnosis (OR = 6.32, 95% CI 1.33-30.01, P = 0.02), Ki-67 <10% (OR = 14.07, 95% CI 2.09-94.9, P = 0.007), and postoperative biochemical remission (OR = 0.023, 95% CI 0.001-0.52, P = 0.018) were beneficial prognostic parameters for recurrence-free survival.

CONCLUSION

Despite a favorable overall prognosis, PC shows high rates of recurrence leading to repeated surgery and postoperative recurrent laryngeal nerve palsy and hypoparathyroidism. In view of the reduced recurrence rate in cases of extended surgery, ipsilateral completion surgery may be considered when PC is confirmed.

Contemporary Evaluation and Management of Parathyroid Carcinoma

Parathyroid carcinoma is a rare malignancy, representing 0.005% of all cancers and 0.5%-1% of all parathyroid disorders. Parathyroid carcinoma occurs equally in males and females, as opposed to primary hyperparathyroidism, which has a female predominance. Patients with parathyroid carcinoma present with symptoms of hypercalcemia, similar to those with benign primary hyperparathyroidism. Parathyroid carcinoma should be suspected when calcium or parathyroid hormone levels are high. Because of the difficulty of discerning parathyroid carcinoma from adenoma preoperatively, the diagnosis of carcinoma is often made only after parathyroidectomy. The goals of surgery are resection with negative margins because surgery represents the only opportunity for cure. Adjuvant therapy with chemotherapy or external beam radiation has not been proven to affect disease-free or overall survival for these patients. Recurrence is common, with reoperation recommended for resectable recurrent disease. Palliation with calcimimetic pharmacotherapy can aid with management of symptomatic hypercalcemia in recurrent or persistent disease after parathyroidectomy. Ultimately, patients succumb to sequelae of hypercalcemia rather than tumor burden.

Parathyroid Pathology

Proliferative pathologic lesions of parathyroid glands encompass a spectrum of entities ranging from benign hyperplastic processes to malignant neoplasia. This review article outlines the pathophysiologic classification of parathyroid disorders and describes histologic, immunohistochemical, and molecular features that can be assessed to render accurate diagnoses.

Parathyroid carcinoma presenting with chronic renal failure and single pulmonary metastasis: A case report

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In patients with CRF it’s difficult to diagnose parathyroid carcinoma.

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The concomitant presence of metastases should lead us to suspect malignant parathyroid lesions.

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In literature there are no cases of parathyroid carcinoma in patients with CRF (chronic renal failure) diagnosed by means of pulmonary metastasis.

Introduction

Parathyroid carcinoma is a rare malignancy. Our case report is unusual for its presentation. The patient referred symptoms compatible with CRF; nodular lesions to parathyroid glands and an elevated PTH induced physician to hypothesize secondary hyperparathyroidism. The presence of haemoptysis gave us suspicion for malignant neoplasm but only histological examination allowed us to recognize the nature of the lesion, because even PET-CT didn’t detect, an hypercaptation in the parathyroids.

Presentation of the case

The case concerns a 59 years old female with the following symptoms: asthenia, oliguresis, nausea, haemoptysis and very high levels of calcium and PTH. Laboratory findings (PTH 570 pg/ml; Ca 12.20 mg/dl; P 1.8 mg/dl), ultrasound, CT scan and parathyroid scintigraphy, associated with clinical data, indicated a parathyroid carcinoma with single pulmonary metastasis of the upper lobe of the left lung, confirmed by histological examination and immunochemistry. Cytology performed with bronchoscopy was negative. Surgery (“en bloc” parathyroidectomy on adjacent structures, lymph node dissection near recurrent nerve and atypical lung resection) was effective, with normalization of calcium and PTH levels and disappearance of symptoms after 48 h. After six months, no signs of local recurrence or metastases were observed.

Discussion

No clinical or bio-humoral data allows a preoperative diagnosis of parathyroid carcinoma. Only with definitive pathology and immunochemistry it is possible to differentiate an adenoma from a carcinoma.

Conclusion

In patients with CRF it’s difficult to diagnose parathyroid carcinoma, because its presentation mimics the most common secondary hyperparathyroidism; the concomitant presence of metastases should lead us to suspect malignant parathyroid lesions.

Surgery is the only effective therapy and therefore should be always performed.

Atypical presentation of oncocytic parathyroid adenoma masquerading as metastatic carcinoma

Parathyroid carcinoma is the rarest endocrine malignancy. Definitive diagnosis is challenging as it is difficult to distinguish malignant from benign disease. A 71-year-old man presented with weight loss and hypercalcaemia. CT scans revealed multiple lung nodules and lytic bone lesions that were consistent with metastatic dissemination. Technetium-99m-sestamibi-single-photon emission computed tomography scan showed an abnormal uptake in the right thyroid lobe. Fine-needle aspiration (FNA) was performed on three occasions. The patient underwent parathyroidectomy with ipsilateral hemithyroidectomy without postoperative complications. Microscopic examination showed a parathyroid neoplasm with fibrosis and intravascular tumour on a background of unremarkable thyroid parenchyma. This resulted in an initial impression of parathyroid carcinoma. Further review by two independent pathologists provided a final diagnosis of oncocytic parathyroid adenoma. This case highlights the subjectivity and interobserver variation with endocrine histological examination. FNA can induce changes that mimic parathyroid carcinoma on histology. An index of suspicion for benign parathyroid adenomas should be maintained.

Challenges in the treatment of parathyroid carcinoma: a case report

INTRODUCTION

Parathyroid carcinoma (PC) is a rare neoplasm with a high rate of recurrence and an indolent course. It is frequently functional, causing nearly 1% of the cases of primary hyperparathyroidism (HPT), and in some cases, it may be complicated by brown tumors, mimicking bone metastases. Synchronous parathyroid and papillary thyroid carcinomas are rare.

CASE REPORT

We present a patient with HPT due to PC, misdiagnosed at first evaluation, which exhibited multiple hypermetabolic lytic lesions in the skeleton, suggesting bone metastases. Their regression after PTH reduction suggested the diagnosis of brown tumors due to severe HPT. Given the persistence of HPT, the patient underwent a number of neck surgeries, and a papillary thyroid microcarcinoma with a nodal metastasis was diagnosed. A genetic test discovered a previously unreported mutation of the CDC73 (HRPT2) gene, codifying for parafibromin and resulting in a premature stop codon (c.580A>Tp.Arg194). Because of the persistence of HPT, cinacalcet therapy was started in order to control hypercalcemia.

CONCLUSION

This is a very unusual patient with a newly discovered variant of the CDC73 gene and a phenotype characterized by recurrent PC, brown tumors, and N1a metastasized thyroid carcinoma. The present case confirms that PC may not exhibit clear malignant properties at first assessment, contributing to inadequate initial surgical treatment. Although infrequently, PC can be associated with papillary thyroid cancer. The diagnosis of brown tumor should be considered in patients with severe HPT and multiple destructive bone lesions mimicking metastases on PET/CT imaging.

Coronary Heart Disease and an Incidental Parathyroid Carcinoma

A 71-year-old woman was admitted with angina pectoris. During hospitalization she developed a myocardial infarction (NSTEMI). Laboratory results revealed a mild elevated troponin and an elevated calcium level (3.35 mmol/l). Subsequently, there was a decreased phosphate (0.36 mmol/l [normal 0.81-1.62 mmol/l]) as well as 16-fold elevated serum level of parathyroid hormone (PTH, 1156 ng/l [normal 10-73 ng/l]), indicating a primary hyperparathyroidism. Sonographically a thyroidal node was detected, not clearly demarcated (TIRADS 5). FNA showed a monomorphic, partial follicular cell population with an immunohistochemical positivity for PTH. Magnetic resonance imaging (MRI) showed a 5 cm large tumor at the right caudal pole of the thyroid with compression of the dorsolateral trachea without infiltration. Surgical removal with en bloc resection of the right hemithyroid with parathyroidectomy was performed. Postoperatively the PTH level dropped to 12.1 ng/l. Pathological examination revealed a 5 cm tumor with infiltration of the thyroid and a perineural invasion. The diagnosis of a presymptomatic parathyroid carcinoma could be established. The affirmative histopathological diagnosis of a parathyroid carcinoma can be challenging and is limited to tumors with evidence of invasive growth in adjacent structures such as the thyroid and/or soft tissue, perineural spaces, angioinvasion of capsular and/or extracapsular vessels, and/or documented metastases.

Current concepts in parathyroid carcinoma: a single Centre experience

BACKGROUND

Parathyroid carcinoma is a rare neoplasm that may present sporadically or in the context of a genetic syndrome. Diagnosis and management are challenging due to the lack of clinical and pathological features that may reliably distinguish malignant from benign disease.

METHODS

From January 2013 to December 2017, from 358 consecutive patients affected by parathyroid diseases, 3 patients with parathyroid carcinoma were treated at our academic Department of General Surgery. We present our experience as illustrative of the different features of clinical presentation of parathyroid carcinoma and review its management considering the recent relevant literature.

RESULTS

Case 1: A 62-year-old man was hospitalized for left-sided palpable neck mass, hypercalcemia and elevated PTH. US-guided FNA was suspect for parathyroid carcinoma. A large cystic mass was excised in bloc with total thyroidectomy and central neck dissection. Genetic studies framed a pathologically confirmed parathyroid carcinoma within MEN1 syndrome. Case 2: A 48-year-old woman with hypothyroidism had total thyroidectomy performed for a suspect for right follicular thyroid lesion. Pathology revealed parathyroid carcinoma. Case 3: A 47 year-old man was admitted for hypercalcaemic crisis and renal failure in the context of PHPT. A lesion suggestive on US and MIBI scan for parathyroid adenoma in the right lower position was removed by mini-invasive approach. Pathology revealed parathyroid cancer and patient had completion hemythyroidectomy and central neck dissection.

CONCLUSION

Parathyroid cancer is a particularly rare endocrine malignancy, however it should be suspected in patients with primary hyperparathyroidism when severe hypercalcemia is associated to cervical mass, renal and skeletal disease. Parathyroid surgery remains the mainstay of treatment. Radical tumour resection and expedited treatment in a dedicated endocrine Center represent crucial prognostic factors.

Previously unreported deletion of CDC73 involving exons 1-13 was detected in a patient with recurrent parathyroid carcinoma

Parathyroid carcinoma (PC) is a rare malignancy, presenting sporadically or as part of a genetic syndrome. Diagnosis of PC includes the histopathological diagnosis based on capsular, perineural, or vascular invasion or metastasis. High suspicion for malignancy includes hypercalcaemia greater than 14 mg/dL, extremely high serum parathyroid hormone (PTH) levels, as well as large masses. Given the rarity of PC, it is challenging to design clinical trials for newer therapy. Currently, complete initial surgical excision of the tumour in high-risk patients offers the best chance of cure and prolonged disease-free survival in PC. In the absence of definite data, non-surgical therapies such as radiation and chemotherapy are not routinely recommended. For early detection of recurrence; long-term clinical follow-up with interval measurements of serum calcium and PTH is recommended. Localising studies of PC are helpful. Early screening for CDC73 mutation and multidisciplinary treatment by an endocrine/ENT/surgical oncology team is recommended.

99mTc-MIBI single photon emission computed tomography/computed tomography for the incidental detection of rare parathyroid carcinoma

This study aimed to evaluate the characteristics of parathyroid carcinoma and to validate the diagnostic value of Tc-methoxyisobutylisonitrile (MIBI) single photon emission computed tomography/x-ray computed tomography (SPECT/CT) for differentiating between parathyroid carcinoma and hyperparathyroidism. Four consecutive patients with suspected primary hyperparathyroidism were enrolled in this study and underwent Tc-MIBI SPECT/CT, ultrasonography, enhanced CT, and MRI. Serum parathyroid hormone (PTH) and calcium were measured. All primary and recurrent lesions showed high focal uptake on Tc-MIBI image, whereas metastatic lymph nodes gave false negative results. The serum PTH was 165.14 ± 90.26 pmol/L, which declined rapidly after surgery. One patient with a persistently high PTH (147.5 pmol/L) after surgery presented with multiple lymphadenopathy in the neck. Higher expression of chromogranin A (CgA) further confirmed parathyroid carcinoma as a rare endocrine tumor. Parathyroid carcinoma is thus usually diagnosed incidentally based on nonspecific multiorgan symptoms of hypercalcemia and hyperparathyroidism. Tc-MIBI SPECT/CT may help to localize the parathyroid carcinoma, while MRI is valuable for detecting metastasis. Serum PTH and CgA serve as circulating biomarkers in parathyroid carcinoma, and raised levels of PTH and CgA together with locoregional lymphadenopathy may indicate parathyroid carcinoma. Further studies are needed.

Parathyroid carcinoma: an unusual presentation of a rare neoplasm

Parathyroid carcinoma is an extremely rare malignant endocrine neoplasm that is very challenging in its diagnosis as well as its treatment. Clinically the disease is detected earlier in patients who present with hyperparathyroidism with signs of profound hypercalcemia. Differentiation between benign and malignant disease of the parathyroid is challenging both for the clinician and for the pathologist. Complete surgical resection at the time of first operation offers the best chance of cure. Even after radical excision which is the standard management, local recurrence and metastases are frequent. The disease usually has a slow indolent course and most patients suffer from complications of hypercalcemia rather than tumor invasion or metastasis. We report a case of a 31-year-old woman who presented with renal colic. Various hematological, biochemical and radiological investigations were performed and a slightly enlarged right parathyroid was found. A clinical diagnosis of parathyroid adenoma was made and a right parathyroidectomy was done. Intraoperatively the surgeon had no suspicion of malignancy but microscopically the lesion was malignant and a final diagnosis of parathyroid carcinoma was rendered based on the criteria of invasion. Since there is no gold standard, a multidisciplinary approach, including the entire clinical, biochemical, radiological and pathological profile of the disease aids in an accurate diagnosis. Here we are reporting a case of a functional parathyroid carcinoma presenting in a relatively young patient with all the biochemical and radiological investigations and intraoperative findings pointing towards a benign parathyroid disease.

Intrathyroidal Parathyroid Carcinoma: An Atypical Thyroid Lesion

Parathyroid carcinoma is a rare endocrine malignancy that is typically difficult to diagnose at presentation. Here, we report a 63 year-old man who had symptomatic hypercalcemia. Investigations revealed a thyroid nodule and a lateral neck mass that was biopsied and diagnosed as "suspicious for a neuroendocrine neoplasm." He underwent total thyroidectomy with central and left neck node dissection. Histology and immunohistochemistry revealed an intrathyroidal angioinvasive parathyroid carcinoma with lymph node metastases. The tumor showed loss of parafibromin expression; germline testing revealed no pathogenic germline variants of CDC73, suggesting either a cryptic germline variant or a sporadic malignancy. Multiple pulmonary nodules consistent with metastatic disease explained persistent hypercalcemia and the patient was treated with denosumab as well as Sorafenib resulting in early regression of the lung nodules. This case illustrates an unusual parathyroid carcinoma with respect to anatomic presentation and the importance of complete pathological workup in securing the diagnosis. The management of these rare malignancies is discussed.

Clinical characteristics and treatment outcomes of parathyroid carcinoma: A retrospective review of 234 cases

Parathyroid carcinoma (PC) is one of the rarest known types of cancer and has a moderate prognosis, with estimated 5- and 10-year overall survival rates between 78–85% and between 49–70%, respectively. To raise awareness of this disease, and to optimize its diagnosis, clinical management and prognosis, the present study retrospectively reviewed 234 cases of PC. A total of 226 cases of PC, which were archived between 1984 and 2015 in the three major databases of the Chinese population, were retrieved and pooled with the 8 cases diagnosed and treated at the Department of Thyroid Surgery of The First Hospital of Jilin University (Changchun, China) between June 2008 and December 2015. The clinicopathological features, diagnosis, surgical procedures and outcomes of these cases of PC were investigated. The review revealed that misdiagnosis has been a considerable issue, with >80% of the patients misdiagnosed prior to surgery, and the accuracy of intraoperative diagnosis based on frozen sections was only 15.04%. The use of radical resection as first-line therapy significantly improved the disease-free survival by ~8 years (log-rank, 20.956; P<0.001); and, at relapse, reoperation prolonged patient survival by ~7 years (log-rank, 35.322; P<0.001). Consistently, a Cox proportional hazards analysis indicated that radical resection as a first-line therapy reduced the risk of postoperative recurrence (P=0.030), and that reoperation following recurrence significantly improved patient survival (P=0.030). The 5- and 10-year cumulative disease-specific survival rates of the cases of PC were 83 and 67%, respectively. Notably, an increased mortality rate was observed among males with PC compared with female patients with PC. In summary, in the past 32 years (1984–2015), the majority of patients with PC have been misdiagnosed. Performing radical resection as the first-line therapy significantly reduces recurrence and improves patient survival time; and, following relapse, subsequent surgery has also been demonstrated to be an effective approach.

Parathyroid Carcinoma in Patients that Have Undergone Surgery for Primary Hyperparathyroidism

BACKGROUND/AIM

Parathyroid carcinoma is a rare clinical entity, which represents one of the main reasons, why surgery should be performed in specialized centres. Preoperatively, it is very difficult to distinguish between benign and malignant hyperparathyroidism.

PATIENTS AND METHODS

During the years 1996-2016, we performed 2,220 operations in 2,075 patients with a diagnosis of primary hyperparathyroidism.

RESULTS

Among these 2,220 operations, there were 16 operations for parathyroid carcinoma. These 16 operations, including reoperations, were performed in four patients. Two patients had no reoperation, but another 2 patients required 14 reoperations in total. Parathyroid carcinoma was described in 0.2% of all patients with a diagnosis of primary hyperparathyroidism. The number of operations was 0.73% of all operations of primary hyperparathyroidism in years 1996-2016.

CONCLUSION

Prognosis of parathyroid carcinoma is quite favourable, patients evidence a long-term survival rate after the primary operation. However, every reoperation increases the number of possible complications, including recurrent laryngeal nerve injury.

[Parathyroid carcinoma: about a case and review of the literature]

Le carcinome parathyroïdien est une tumeur maligne, très rare, de la glande parathyroïde. Cliniquement, ce cancer se présente souvent par un tableau d'hyperparathyroïdie primaire sévère. Le diagnostic est histologique mais n'est pas toujours aisé. Le traitement est basé sur la chirurgie. Femme âgée de 59 ans, aux antécédents d'hypertension artérielle, et de lithiases rénales récidivantes, consultait pour des douleurs osseuses diffuses avec asthénie. L'examen du cou a trouvé une tuméfaction basi-cervicale dure et à bord inférieur non palpable. A la biologie: hypercalcémie à 4,1 mmol/l, une hyperparathyroïdie avec valeur de parathormone (PTH) très élevée à 1088 pg/ml soit 13 fois la normale. La scintigraphie au Technétium-99m-sestamibi a montré une plage de fixation anormale de MIBI en projection de la parathyroïde inférieure gauche. Une parathyroïdectomie inférieure gauche, avec évidement médiastino-récurrentiel homolatéral ont été réalisés. Les suites opératoires étaient marquées par la normalisation de la calcémie et de la PTH. L'anatomopathologie était en faveur d'un carcinome parathyroïdien. Le diagnostic de carcinome parathyroïdien est généralement établi sur la conjonction de signes radiologiques biologiques et histologiques. La gravité de cette pathologie est due à l'hypercalcémie sévère et au risque de récidive et de métastases à distance justifiant la surveillance prolongée.

Giant parathyroid adenoma: differential aspects compared to parathyroid carcinoma

The 85% of cases of primary hyperparathyroidism (PHPT) are due to parathyroid adenomas (PA) and less than 1% to parathyroid carcinomas (PC). The PA usually measure <2 cm, weigh <1 g and generate a mild PHPT, whereas the PC usually exceeds these dimensions and are associated with a severe PHPT. However, giant PA (GPA), which is defined as those larger than 3 g, has been documented. Those may be associated with very high levels of PTH and calcium. In these cases, their differentiation before and after surgery with PC is very difficult. We present a case of severe PHPT associated with a large parathyroid lesion, and we discuss the differential aspects between the GPA and PC.

Prognostic Scoring System to Risk Stratify Parathyroid Carcinoma

BACKGROUND

Parathyroid carcinoma is a rare endocrine malignancy that lacks an established system for risk categorization. This study evaluated a prognostic scoring system for recurrence-free survival (RFS) of patients with parathyroid carcinoma.

STUDY DESIGN

Patients diagnosed and confirmed to have parathyroid carcinoma and who were treated between 1980 and 2016 at The University of Texas MD Anderson Cancer Center were studied retrospectively. Univariate and multivariate Cox proportional hazards regression analyses of RFS were conducted. A prognostic scoring system was created based on multivariate analysis.

RESULTS

Sixty-eight patients were evaluated. After a median follow-up of 4.6 years, 26 patients experienced a recurrence. The Kaplan-Meier RFS rates were 85% at 1 year (95% CI 77% to 95%), 67% at 2 years (95% CI 55% to 81%), and 51% at 10 years (95% CI 36% to 72%) after initial operation. Multivariate analysis demonstrated that age older than 65 years, serum calcium level >15 mg/dL, and vascular invasion were negatively correlated with RFS rate. Combining these adverse variables into a prognostic scoring system, we stratified patients into 3 risk groups: low (0 variable; 2-year RFS rate, 93%), moderate (1 variable; 2-year RFS rate, 72%), and high (2 variables; 2-year RFS rate, 27%) (p = 0.001 [log-rank test]; concordance index, 0.70; 95% CI 0.47 to 0.92).

CONCLUSIONS

A prognostic scoring system using vascular invasion, age, and serum calcium level at initial parathyroidectomy can be used to predict RFS. This categorization might be helpful for clinical decisions relative to the timing and use of adjuvant therapy. Comprehensive validation using multiple cohorts will be needed to confirm applicability.

Preoperative diagnosis and prognosis in 40 Parathyroid Carcinoma Patients

OBJECTIVE

Parathyroid carcinoma (PC) is a rare disease which is difficult to diagnose preoperatively and predict prognosis. The goal of this study was to analyse the preoperative predictive factors and prognostic factors in PC patients and to evaluate the possibility of diagnosing PC preoperatively.

DESIGN, SETTING AND PATIENTS

This is a retrospective study from Jan 2000 to Aug 2015 conducted in Shanghai Ruijin Hospital.

MEASUREMENTS

Comparisons were made between 40 parathyroid carcinoma patients and 282 patients with benign parathyroid lesions during the same period. All patients underwent parathyroid surgery, and the results were certified by paraffin pathology. Prognostic factors were analysed in the 40 PC patients.

RESULTS

Patients with higher levels of intact parathyroid hormone (P < 0·001, OR = 1·001, CI: 1·000-1·002), calcium (P = 0·008, OR = 3·395, CI: 1·382-8·341) and a larger parathyroid volume (P = 0·001, OR = 2·023, CI: 1·333-3·071) were more likely to have PC. Local excision (P = 0·008, OR = 4·992, CI: 1·533-16·252), stage III in the Schulte staging system (P = 0·039, OR = 9·600, CI: 1·12-82·322), high risk in the Schulte Risk Classification (P = 0·012, OR = 5·466, CI: 1·448-20·628) and first surgery by other medical teams (P = 0·008, OR = 4·992, CI: 1·496-15·037) were associated with PC recurrence. Calcium (P = 0·01, OR = 7·270, CI: 1·611-32·812), intact parathyroid hormone (P = 0·037, OR = 1·001, CI: 1·000-1·001), local excision (P = 0·009, OR = 6·875, CI: 1·633-28·936) and recurrence (P = 0·014, OR = 7·762, CI: 1·504-40·055) were associated with death.

CONCLUSIONS

A preoperative diagnostic system may provide a new method to distinguish PC from benign parathyroid lesions before surgery. For PC patients who did not undergo en-bloc resection at first operation, timely further surgery may offer a second chance of cure. Early diagnosis and surgery are pivotal to reduce mortality in PC patients.

Parathyroid carcinoma: A report of six cases with a brief review of the literature

Parathyroid carcinoma (PC) is an uncommon endocrine malignancy and constitutes a rare cause of hyperparathyroidism. The current study presents the clinical features, laboratory findings, sensitivity of imaging modalities, surgical treatment and the long-term outcome of six patients, who were diagnosed with PC and treated in the Department of Head and Neck Surgery, Zhejiang Province Cancer Hospital (Hangzhou, China) over 13 years (February 1999-January 2012). Pre-operative recognition and intraoperative identification of this rare endocrine malignancy is extremely important, but require a high index of clinical suspicion. The primary treatment is surgical en bloc resection of the tumor and any involved surrounding structures, and it is of great importance, as the prognosis depends on the initial surgery. Radiation therapy and chemotherapy showed no evidence of effectiveness on PC, although certain data show a decreased risk of localized disease recurrence with the addition of radiation therapy. The prognosis of PC is variable and post-operative parathyroid hormone levels that do not decrease often indicate a poor prognosis or presence of other metastases.

Non-functional parathyroid carcinoma: a case report and review of the literature

Non-functional parathyroid carcinoma is an exceedingly rare disease with 31 reported cases since 1909. Because of the scarce number of cases of non-functional parathyroid carcinoma, there are no evidence-based recommendations for its optimal treatment. Surgery, including en bloc resection of the carcinoma, ipsilateral thyroid lobe and isthmus together with a neck dissection only in case of lymph node involvement, is the main treatment for non-functioning parathyroid carcinoma. The patient usually has a poorer prognosis because of detection at advanced stages, the relative ineffectiveness of adjuvant treatment modalities and the lack of adequate parameters for clinical follow-up. In this report, we present a case of non-functional parathyroid carcinoma at our institution, and we review the previous literature to discuss the latest advances in the diagnosis and treatment of this rare disease.

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.

Case of parathyroid carcinoma with a highly aggressive clinical course

We describe a 59-year-old woman who presented with pathological osteoporosis, cerebral infarction, hypercalcemia, and markedly high parathyroid hormone levels. The diagnosis was primary hyperparathyroidism, and parathyroidectomy was performed. Histopathological examination showed parathyroid adenoma. Surgical exploration for recurrent parathyroid carcinoma was undertaken at 2 and 3 years after the initial neck resection. Pulmonary metastasis was diagnosed at 4 years after the initial surgery.Despite treatment with intravenous bisphosphonates, her calcium and parathyroid hormone (PTH) levels remained elevated, and leg amputation was performed following the development of arteriosclerosis obliterans at 6 years after the initial neck resection. The prognosis for parathyroid carcinoma is often difficult to predict due to recurrence.

Oncologic resection achieving r0 margins improves disease-free survival in parathyroid cancer

BACKGROUND

Parathyroid cancer has a poor mid-term prognosis, often because of local recurrence, observed in half of all patients. Modern diagnostic workup increasingly enables a preoperative diagnosis of parathyroid cancer. There is limited evidence that more comprehensive oncologic surgery can reduce the risk of local recurrence. This study aims to identify the best specific surgical approach in parathyroid cancer.

METHODS

This observational cohort study comprises 19 consecutive patients who had undergone oncologic or nononcologic resection for parathyroid cancer. Baseline parameters were compared by using univariate analysis; outcomes were assessed by χ (2) testing and Kaplan-Meier statistics.

RESULTS

Fifteen of 19 patients were primarily operated on in our tertiary center between 1996 and 2013, and four were referred for follow-up because of their cancer diagnosis. Patient cohorts defined by histologic R-status were comparable for established risk factors: sex, calcium levels, low-risk/high-risk status, and presence of vascular invasion. Oncologic resections were performed in 13 of 15 patients primarily treated in the center and 0 of 4 treated elsewhere (χ (2) = 5.6; p < 0.01). R0 margins were achieved in 11 of 13 (85 %) undergoing oncologic resection and 1 of 6 (17 %) undergoing local excision (χ (2) = 8.1; p < 0.01). R0 margins and primary oncologic resection were associated with higher disease-free survival rates (χ (2) = 7.9; p = 0.005 and χ (2) = 4.7; p = 0.03, respectively). Revision surgery achieved R0 margins in only 2 of 4 (50 %) of patients.

CONCLUSIONS

In parathyroid cancer, a more comprehensive surgery (primary oncologic resection) provides significantly better outcomes than local excision as a result of reduction of R1 margins and locoregional recurrence.

Parathyroid carcinoma

Parathyroid carcinoma is a rare form of endocrine malignancy accounting for only a small minority of cancer cases. Due to the rarity of this cancer, there are no generalized guidelines for its management; however, surgery remains to be the mainstay therapy. The purpose of this article is to review and summarize the available literature on parathyroid carcinoma, while discussing proposed staging systems and the role of available adjuvant therapies.

Parathyroid carcinoma: challenges in diagnosis and treatment

Parathyroid carcinoma is a malignant neoplasm affecting 0.5% to 5.0% of all patients with primary hyperparathyroidism. Since it was first described by De Quervain in 1904 to this day, it continues to defy diagnosis and treatment because of its rarity, overlapping features with benign parathyroid disease, and lack of distinct characteristics. En bloc surgical extirpation of the tumor with clear margins remains the best curative treatment. Although prolonged survival is possible with recurrent or metastatic disease, cure is rarely achievable. Efficacy of adjuvant therapies, such as radiotherapy and chemotherapy, in management of persistent, recurrent, or metastatic disease has been disappointing.

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.

Parathyroid carcinoma: update and guidelines for management

Parathyroid carcinoma is one of the rarest known malignancies that may occur sporadically or as a part of a genetic syndrome. It accounts for approximately 1% of patients with primary hyperparathyroidism. The majority (90%) of parathyroid cancer tumors are hormonally functional and hypersecrete parathyroid hormone (PTH). Thus, most patients exhibit strong symptomatology of hypercalcemia at presentation. Sometimes, it can be difficult to diagnose parathyroid cancer preoperatively due to clinical features shared with benign causes of hyperparathyroidism. Imaging techniques such as neck ultrasound and 99mTc sestamibi scan can help localize disease, but they are not useful in the assessment of malignancy potential. Fine needle aspiration (FNA) prior to initial operation is not recommended due to technical difficulty in differentiating benign and malignant disease on cytology specimens and the possible associated risk of tumor seeding from the needle track. Complete surgical resection with microscopically negative margins is the recommended treatment and offers the best chance of cure. Persistent or recurrent disease occurs in more than 50% of patients with parathyroid carcinoma. Surgical resection is also the primary mode of therapy for recurrence since it can offer significant palliation for the metabolic derangement caused by hyperparathyroidism and allows hypercalcemia to become more medically manageable. However, reoperation is rarely curative and eventual relapse is likely. Chemotherapy and external beam radiation treatments have been generally ineffective in the treatment of parathyroid carcinoma. Typically, these patients require repeated operations that predispose them to accumulated surgical risks with each intervention. In inoperable cases, few palliative treatment options exist, although treatment with calcimimetics can effectively control hypercalcemia in some patients. Most patients ultimately succumb to complications of hypercalcemia rather than from tumor burden or infiltration.

Classification of parathyroid cancer

PURPOSE

Parathyroid cancer is rare and often has a poor outcome. There is no classification system that permits prediction of outcome in patients with parathyroid cancer. This study was designed to validate two prognostic classification systems developed by Talat and Schulte in 2010 ("Clinical Presentation, Staging and Long-term Evolution of Parathyroid Cancer," Ann Surg Oncol 2010;17:2156-74) derived from a retrospective literature review of 330 patients.

METHODS

This study contains 82 formerly unreported patients with parathyroid cancer. Death due to disease was the primary end point, and recurrence and disease-free survival were the secondary end points. Data acquisition used a questionnaire of predefined criteria. Low risk was defined by capsular and soft tissue invasion alone; high risk was defined by vascular or organ invasion, and/or lymph node or distant metastasis. A differentiated classification system further classified high-risk cancer into vascular invasion alone (class II), lymph node metastasis or organ invasion (class III), and distant metastasis (class IV). Statistical analyses included risk analysis, Kaplan-Meier analysis, and receiver-operating characteristic (ROC) analysis.

RESULTS

Follow-up ranged 2-347 months (mean 76 months). Mortality was exclusive to the high- risk group, which also predicted a significant risk of recurrence (risk ratio 9.6; 95% confidence interval 2.4-38.4; P < 0.0001), with significantly lower 5-year disease-free survival (χ(2) = 8.7; P < 0.005 for n = 45). The differentiated classification also provided a good prognostic model with an area under the ROC curve of 0.83 in ROC analysis, with significant impairment of survival between classes (98.6%, 79.2%, 71.4%, 40.0%, P < 0.05 between each class).

CONCLUSIONS

This study confirms the validity of both classification systems for disease outcome in patients with parathyroid cancer.