Endocrine Abstracts

Introduction: Parathyroid Carcinomas are rare malignant neoplasms, accounting for less than 1% of primary hyperparathyroidism cases. Apart from certain genetic mutations, no additional risk factors are known. Diagnosis is challenging in the absence of metastatic disease since no consensual histological criteria have so far been developed. These neoplasms typically present with severe hypercalcemia and markedly elevated serum PTH levels. Treatment is surgical and despite frequent metastatic disease at diagnosis, clinical course is usually indolent. The authors report the experience of a tertiary reference centre in Portugal regarding parathyroid carcinomas.

Methods: Observational, retrospective study. Patients with diagnosed parathyroid carcinoma from 1999 until 2016 were included. Clinical data was obtained from patient’s clinical, laboratory and imaging files. Descriptive statistical methods were used and results are presented as mean and standard deviation.

Results: The sample is composed of ten patients (five females) with a median age of 53±16.9 years at the time of diagnosis. Clinical presentation was heterogeneous. All patients had hyperparathyroidism (mean 1229±642 pg/ml), nine hypercalcemia (13.4±2.2 mmol/l) and four hypophosphatemia (2.1±0.6 mol/l). Histological findings: intratumoral septa (50%), vascular, capsular, perineural invasion (70%, 80%, 10% respectively), extraglandular extension (50%). Mitotic index was evaluated in four patients. CDC73 mutations were present in four patients. Metastases were present in one patient. All patients underwent en bloc resection and three received external beam radiotherapy due to recurrent loco-regional disease. After a mean follow up of 9 years, 90% are in remission and no mortality has been documented.

Conclusion: The authors describe a series of ten parathyroid carcinoma patients. Despite the clinical and biochemical severity at the time of diagnosis, most patients achieved sustained remission. Genetic mutations were identified in a significant proportion of patients, having important clinical implications. This series is noteworthy for the good outcome of such an aggressive neoplasm.