[Parathyroid carcinoma: multicenter study of 17 patients]

Hypercalcemia of Malignancy Revealing a Parathyroid Carcinoma with Hepatic Metastasis: A Case Report and Literature Review

Parathyroid carcinoma is a very rare malignant tumor of the parathyroid gland. This cancer poses a great diagnostic and therapeutic difficulty due to its rarity and the absence of a characteristic clinical and paraclinical picture. The diagnosis is histological but is not always easy. Surgery remains the only curative treatment, and cervical radiotherapy can be discussed. Good prognostic factors are complete monobloc tumor resection, and bad prognostic factors are the presence of lymph node metastases at diagnosis, distant metastases, and nonsecreting carcinomas.

[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.

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.

Clinical presentation, staging and long-term evolution of parathyroid cancer

BACKGROUND

Parathyroid cancer is rare and often fatal. This review provides an in-depth analysis of 330 clinical cases reported in detail. These data are used to inform a proposal for a hitherto lacking TNM staging system.

MATERIALS AND METHODS

All case reports or series with sufficient case details of parathyroid cancer were identified from PubMed, and data were analyzed using SPSS.

RESULTS

Of 330 patients, 117 (35%) died of disease and 207 (63%) experienced recurrence in a total of 2007 follow-up years and a mean length of follow-up of 6.1 years. Histopathology findings rather than biochemical or clinical features predict outcome. In univariate analysis, survival and recurrence rates are significantly influenced by gender (male relative risk [RR] 1.7, 95% confidence interval [95% CI] 1.0-2.7, P < .01), and presence of vascular invasion (RR 4.3, 95% CI 1.1-17.7, P < .01), or lymph node metastases (RR 6.2, 95 %CI 0.9-42.9, P < .001). Failure to perform oncological surgery carries a high risk for recurrence and death (local versus en bloc resection RR 2.0, CI 1.2-3.2, P < .01) as for redo surgery. Staging by a novel anatomy-based TNM system identifies significant outcome variation as to recurrence and death. Separation of patients into low and high risk identifies a 3.5-7.0 fold higher risk of recurrence and death (P < .01) for the high-risk group. Distant metastases predominantly target mediastinum and lung.

CONCLUSION

Understaging and undertreatment are shown to contribute to high recurrence rates and death toll. To improve outcome, en bloc resection including central lymph node dissection should be the minimal surgical approach in any patient with suspected parathyroid cancer.