A Rare Case of Parathyroid Cancer

By: Dr. Jamie Mitchell, Jon Finan, Maria Sheppard

Parathyroid cancer is already one of the rarest cancers, but in an even smaller group of patients, the tumor does not cause abnormal calcium levels in the blood. These are called nonfunctional parathyroid carcinomas, and they are especially hard to detect.

One such case involved a 58-year-old woman who first came to medical attention in 2016 with a large thyroid mass. After surgery, the tissue was found to be a parathyroid cancer—even though her calcium and parathyroid hormone (PTH) levels were normal. Without the usual signs of parathyroid disease, her cancer was nearly impossible to recognize before surgery.

Unfortunately, the cancer returned multiple times over the following years. Because her blood tests remained normal, doctors had to rely on imaging scans to look for recurrence. She underwent several additional operations to remove new tumor growths, but each surgery carried risks and caused side effects, including vocal cord paralysis. By 2023, after another recurrence, she chose not to pursue further surgery because of concerns about long-term complications.

This case highlights the unique challenges of nonfunctional parathyroid carcinoma:

• Hard to diagnose early – because blood calcium and PTH levels stay normal.

• Difficult to monitor – because doctors cannot use PTH as a tumor marker and must rely on imaging, which is less precise.

• Limited treatment options – surgery is the only proven therapy, but repeated operations may cause significant side effects, and chemotherapy or radiation have not been shown to work.

For most parathyroid cancers, the greatest danger comes from uncontrolled calcium levels. But in nonfunctional cases like this one, the challenge is different: balancing aggressive surgery with the risks it brings, especially when the disease recurs.

Understanding these rare cases is important because they show the limits of today’s diagnostic tools and the need for better ways to detect and monitor parathyroid cancer. Research into genetic markers, improved imaging, and safer surgical strategies could help change the outlook for future patients facing this extraordinarily rare disease.