Recurrence of Hyperparathyroid Hypercalcemia in a Patient With the HRPT-2 Mutation and a Previous Parathyroid Carcinoma in Hyperparathyroidism-Jaw Tumor Syndrome

INTRODUCTION Cancer in the parathyroid gland is rare, but parathyroid cancer is occasionally seen in relation to genetic abnormalities. Due to a limited amount of evidence, the optimal handling of these cases is not clear. Furthermore, the presence of a malignant parathyroid tumor is rarely known at the time of the initial operation; therefore, re-operations are often necessary. The aim of this study was to present the case of a patient with a previously diagnosed jaw tumor and parathyroid carcinoma that presents as a recurrence of hyperparathyroid hypercalcemia. CASE PRESENTATION A 41-year-old patient who was already diagnosed with a parathyroid carcinoma and a jaw tumor caused by a CDC73 mutation, presented with biochemical evidence of increasing parathyroid hormone (PTH) and calcium levels after a previous total parathyroidectomy. The patient's ionized calcium increased to 1.55 mmol/L and PTH increased to 16.0 pmol/L. A previous genetic analysis revealed a mutation in the CDC73 gene. There was no family history of hyperparathyroidism. We performed a sestamibi scintigraphy and an 11-C methionine (MET) positron emission tomography (PET) scan that showed a recurrence on the left side of the trachea. The patient underwent a third neck operation for the removal of a tumor on the left side of the trachea. The pathology report revealed that the tumor was a lymph node metastasis from the previous parathyroid carcinoma. The patient is currently enrolled in our follow-up regime. Hyperparathyroidism-jaw tumor (HPT-JT) syndrome is a rare autosomal dominant disorder characterized by a parathyroid adenoma or carcinoma, fibro-osseous lesions (ossifying fibroma) of the mandible and maxilla, and renal cysts and tumors. This autosomal dominant familial cancer syndrome has been reported with a variable and incomplete penetrance, and up to 10% of gene carriers do not show any clinical manifestations. Here we present a patient's case and discuss the literature related to this condition. CONCLUSIONS The recurrence of hyperparathyroid hypercalcemia in HTP-JT syndrome after an initial total parathyroidectomy is a well-known condition necessitating careful management, an evaluation of any underlying genetic abnormality, and a family examination. A surgical treatment and surveillance of calcium and PTH measurements are necessary to prevent a recurrence.