A Case Report on Parathyroid Carcinoma - an Extremely Rare Endocrine Malignancy

Background: Parathyroid carcinoma is an extremely rare endocrine malignancy with a prevalence of &It 1%. It is associated with hyperparathyroidism-jaw tumor syndrome (HJTS), multiple endocrine neoplasia (MEN) type 1 or 2A syndromes, secondary hyperparathyroidism, and chronic kidney disease. Incidence is equal in both men and women. Patients may present with symptoms of hypercalcemia, and should be further worked up with neck ultrasound, Tc-99m sestamibi imaging, single-photon emission computed tomography, magnetic resonance imaging, positron emission tomography combined with CT scan, and biopsy of the parathyroid mass. Parathyroid carcinoma can be treated surgically with complete resection. Patients treated with En-bloc resection with microscopically negative margins remain cancer-free for at least three years to a maximum of twenty years. Case Report: A 50-year-old female treated with laparoscopic sleeve gastrectomy for morbid obesity, came for the follow-up visit. She denied any active complaint. Routine Lab work showed mild hypercalcemia, hypophosphatemia, elevated PTH, and alkaline phosphatase. Neck ultrasound showed a cystic lesion adjacent to the right thyroid lobe. Sestamibi (MIBI) parathyroid scintigraphy showed increased radiopharmaceutical uptake by the right superior parathyroid gland without any enlarged or suspicious lymph nodes. Dexa scan was positive for osteopenia. The patient underwent right superior parathyroidectomy along with en-bloc right thyroid lobectomy. Histological examination revealed anaplastic regions, giant cells with abundant cytoplasm, and polymorphous nuclei with a Ki-67 labeling index of 10% consistent with parathyroid carcinoma. Post-surgery imaging with ultrasound and magnetic resonance imaging of the neck computed tomography of the chest, and abdomen, whole-body MIBI scintigraphy was negative for residuals or metastatic disease. She was started on oral calcium carbonate and was monitored regularly with routine lab work. The most recent lab work was within normal limits. Conclusion: Most of the patients with parathyroid carcinoma present in the early stage with the symptoms of hypercalcemia. Many of them do not have symptoms of mass or tumor effects. Parathyroid cancer is a rare malignancy and can be missed, therefore all patients with hypercalcemia should be further evaluated with lab work, imaging, and biopsy to rule out parathyroid carcinoma. Early diagnosis and treatment have a better outcome.