A 21-year-old woman with no pathological history, who consults for a routine check-up. Neck examination revealed a 2-centimeter hard cervical swelling and shoulder tumor was palpated. Laboratory: hypercalcemia, Parathyroid Hormone (PTH) very high at 1312pg/ml, that is, more than 15 times normal. Technetium-99m-sestamibi scintigraphy showed an area of abnormal MIBI fixation on the right lower parathyroid projection. Right upper and lower parathyroidectomy with right lobectomy and surrounding adipose tissue was performed. The postoperative course was marked by normalization of serum calcium and PTH. The pathology was in favor of a parathyroid carcinoma. The diagnosis of parathyroid carcinoma is usually established by the combination of radiological and histological signs. The severity of this pathology is due to severe hypercalcemia and the risk of recurrence and distant metastasis that justify prolonged surveillance.