Introduction: Parathyroid cancer (PTC) is an extremely rare malignancy with an incidence of 5.7 per 10 million people. The exact preoperative or intraoperative diagnosis is difficult, but of paramount importance, because resection with negative margins is the only effective treatment.
Case report: A 46-years-old female was referred from another hospital with a diagnosis of "hyper-functioning thyroid nodule", based on the ultrasound showing a lesion of the right thyroid lobe and elevated FT4. At the admission, she had severe pain in the right inguinal area, fatigue, muscle weakness, and excessive diuresis. The blood assay demonstrated serum calcium of 4.02 mmol/l, parathyroid hormone of 1433.2 pg/ml, FT4 of 17.49 pmol/l, creatinine of 296 μmol/l. CT showed a tumor of the right thyroid lobe with a size of 2.5. A right lobectomy was performed. Right parathyroid glands were not found. Because of the constellation for hyperparathyroidism and suspicion of parathyroid malignancy ipsilateral and central lymph node dissection and partial removal of the right sternothyroid muscle were performed, which correlated with a significant intraoperative drop in the parathyroid hormone. Three months later, a re-resection was performed because of SPECT-CT evidence for residual parathyroid tissue.
Conclusion: The timely diagnosis of PTC is a prerequisite for a good outcome. The best preoperative indicators are serum parathyroid hormone > 4 times above the upper limit, serum calcium > 14 mg/dL, a palpable neck mass, and a local invasion found intraoperatively. The only curative treatment is the complete removal of the tumor with a negative margin.
Key words: Delayed diagnosis, Hyperparathyroidism, Parathyroid cancer, Surgery.