# Understanding Parathyroid Carcinoma: A Patient’s Guide to Diagnosis, Treatment, and Life After Surgery

Parathyroid carcinoma (PC) is an extremely rare cancer of the parathyroid glands — the tiny glands in the neck that regulate calcium in the blood. It accounts for less than 1% of all cases of primary hyperparathyroidism and approximately 0.005% of all cancers, but it can cause dangerously high calcium levels and severe damage to the kidneys and bones. This article translates a 2024 clinical review from The Journal of Clinical Endocrinology & Metabolism, which uses the story of a 50-year-old patient to walk through how doctors diagnose and treat this challenging disease — from first symptoms through surgery, recurrence, and long-term management.

# Understanding Parathyroid Carcinoma: A Patient’s Guide to Diagnosis, Treatment, and Life After Surgery

## Table of Contents

- Key Points
- One Patient’s Story: A 50-Year-Old Man with Severe Symptoms
- Background: What Is Parathyroid Carcinoma?
- Clinical Presentation: How Doctors Suspect Parathyroid Carcinoma
- Perioperative Management: Preparing Patients with Dangerous Calcium Levels for Surgery
- Surgical Approach: Why the First Operation Matters Most
- Pathological Diagnosis: How the Lab Confirms Cancer
- Germline Mutation Testing: The Genetics of Parathyroid Carcinoma
- Key Red Flags: Factors That Raise Suspicion of Parathyroid Carcinoma
- Limitations: What the Medical Community Still Doesn’t Know
- Recommendations: What Patients Should Do
- Frequently Asked Questions
- Source Information

## Key Points

- Parathyroid carcinoma is very rare, causing severe hypercalcemia and organ damage, but can be managed with the right team and vigilant follow-up.
- Recognize red flags: calcium above 14 mg/dL, very high PTH, kidney stones, bone disease, neck mass, or vocal cord paralysis.
- Germline CDC73 testing is recommended for all patients with parathyroid carcinoma to guide follow-up and family screening.
- Avoid fine-needle biopsy of suspected parathyroid masses due to unreliable results and risk of tumor seeding.

## One Patient’s Story: A 50-Year-Old Man with Severe Symptoms

The case begins in September 2009, when a 50-year-old man was admitted to the hospital after a full year of distressing symptoms: nausea, constipation, increased thirst, severe pain in his knees and shins, and marked fatigue.

His medical history provided important clues. Since age 34, he had suffered from recurrent kidney stones in both kidneys (bilateral nephrolithiasis). More recently, he had experienced multiple fragility fractures — broken bones from minimal trauma — in his hip and both upper arm bones (humeri). His past medical history and family history were otherwise unremarkable.

Blood tests revealed a striking picture. His serum calcium was severely elevated at 18 mg/dL (normal range: 8.1–10.4 mg/dL), and his parathyroid hormone (PTH) level was extraordinarily high at 2058 ng/L (normal range: 15–65 ng/L). These results confirmed a diagnosis of **primary hyperparathyroidism** (PHPT), a condition in which one or more parathyroid glands overproduce PTH, pulling calcium out of the bones and into the bloodstream.

He was initially treated with intravenous fluids, a diuretic called furosemide, and bisphosphonates (medications that slow bone breakdown). This treatment progressively brought his calcium down to 13 mg/dL — still above normal, but safer.

Imaging studies came next. A 99mTc-sestamibi scan (a specialized nuclear medicine scan for parathyroid tissue) showed an enlarged parathyroid gland at the lower pole of the right thyroid lobe. A total-body contrast-enhanced computed tomography (CT) scan revealed an 8-centimeter parathyroid mass tightly adhered to the thyroid lobe, as well as multiple **brown tumors** — bone lesions caused by long-standing excess PTH — in his long bones, vertebrae, ribs, and scapulae (shoulder blades).

In October 2009, surgeons removed the right inferior parathyroid gland along with the ipsilateral thyroid lobe (the thyroid lobe on the same side). Because the tumor was strongly adherent to surrounding tissue, the inferior laryngeal nerve was partially resected (cut away) as well. Interestingly, the surgical report made no mention of local invasion — a detail that would matter later.

Soon after surgery, the patient developed **hungry bone syndrome**, a condition where bones rapidly absorb calcium from the blood after years of being depleted. He required treatment with calcium and calcitriol (the active form of vitamin D) for 8 months to keep his blood calcium stable.

In November 2010, roughly a year after his surgery, he was referred to the outpatient clinic at the University of Pisa for further consultation. He felt generally well, and no masses were felt in his neck. His serum calcium was normal at 9.3 mg/dL (normal range: 8.6–10.2 mg/dL), but his PTH was slightly elevated at 121 ng/L (normal range: 10–75 ng/L). His estimated glomerular filtration rate (eGFR), a measure of kidney function, was reduced at 61 mL/min/1.73 m², indicating early kidney impairment.

An abdominal ultrasound showed calcium deposits inside both kidneys (bilateral nephrocalcinosis). A bone density test (dual-energy x-ray absorptiometry, or DXA) revealed marked bone loss in the lumbar spine (T-score −3.1), femoral neck (T-score −2.9), and the distal third of the radius in the forearm (T-score −6.6) — the last being a profound level of bone thinning. X-rays of the skeleton showed that his previously identified bone lesions had fully healed.

Over the next 18 months, his serum calcium and PTH levels gradually climbed — calcium up to 14 mg/dL and PTH up to 393 ng/L. An ultrasound found two lesions in the neck at the site of his prior surgery (measuring 10 and 18 mm), and a 99mTc-sestamibi scan showed increased uptake on the right side of the neck. Two additional neck lesions were identified, the largest reaching 20 mm.

Looking at the whole picture — his relatively young age, male sex, extremely high calcium and PTH at diagnosis, bone and kidney involvement, and the size of the original tumor — doctors strongly suspected **parathyroid carcinoma** (PC), a rare but serious cancer of the parathyroid gland.

Further imaging with total-body CT and positron emission tomography (PET)/CT using 18F-FDG confirmed the disease had returned in the neck, with no evidence of spread (metastases) elsewhere in the body.

This patient’s journey — from severe symptoms, to surgery, to recurrence — illustrates the core challenge of parathyroid carcinoma: it can be difficult to diagnose before surgery, tends to recur, and requires a coordinated, experienced medical team to manage at every step.

## Background: What Is Parathyroid Carcinoma?

Parathyroid carcinoma is a very rare malignancy. It accounts for less than 1% of all cases of primary hyperparathyroidism and approximately 0.005% of all cancers. It is usually associated with severe, symptomatic primary hyperparathyroidism — meaning patients often have strikingly high calcium levels and related symptoms.

Recent reports from several countries (the United States, Australia, Finland, China, and South Korea) indicate that the incidence of PC is rising. The authors note this increase may be partly explained by better diagnostic accuracy, but it may also reflect a true increase in how often the disease occurs.

Here are the key numbers from international registries:

- The largest U.S. series, from the **Surveillance, Epidemiology and End Results (SEER)** database, included **609 cases** of PC diagnosed between 1975 and 2016.
- The largest Asian series came from South Korea (**255 cases**, 2003–2017) and China (**234 cases**, 1984–2015).
- Chinese data showed a marked increase in diagnosed cases: from **13 cases between 1996 and 2000** to **more than 100 cases between 2011 and 2015**.

PC is generally diagnosed in the fifth decade of life (typically in a person’s 40s or 50s) — usually about 10 years earlier than benign parathyroid adenoma. Unlike benign parathyroid tumors, in which women outnumber men by a ratio of 3–4:1, PC shows no sex preference.

PC most commonly occurs as a sporadic disease affecting a single gland. **Somatic mutations** (genetic changes that occur in a person’s lifetime, not inherited) in a gene called **CDC73** are found in up to **80%** of patients with apparently sporadic PC. Approximately **30%** of cases harbor a **germline** (inherited) CDC73 mutation, suggesting that a genetic predisposition plays an important role in many patients.

The CDC73 gene codes for a 531-amino acid protein called **parafibromin**. This protein is primarily found in the nucleus of cells and is a component of a complex called PAF1 that regulates gene transcription and affects how DNA is packaged (chromatin organization). When parafibromin is chemically modified by tyrosine phosphorylation, it acts as a tumor suppressor — it inhibits cell growth by suppressing Cyclin D1 and the MYC proto-oncogene. When it is dephosphorylated, however, it can act as an oncogene, forming a complex with β-catenin and activating signaling pathways (Wnt, Hedgehog, and Notch) involved in development and tissue maintenance. Outside the nucleus, parafibromin also regulates the cell’s internal skeleton (actin cytoskeleton) and inhibits p53-mediated cell death (apoptosis).

For diagnosing PC, the loss of parafibromin immunoreactivity in the nucleus of tumor cells is considered a reliable marker of CDC73 alterations.

Mutations in other genes — including **PRUNE2, KMT2D, CDKN2C, PIK3CA**, and key genes in the PI3K/AKT/mTOR pathway — have also been reported in PC.

PC may also occur as part of **hyperparathyroidism–jaw tumor syndrome (HPT-JT)**, a rare autosomal dominant inherited disorder in which **37%** of affected patients develop parathyroid carcinoma. HPT-JT is characterized by primary hyperparathyroidism, jaw tumors (ossifying fibromas), and, in some cases, kidney lesions and uterine tumors.

A small minority of PC patients — about **2%**, mostly in their seventh decade of life — have **nonfunctioning PC**, meaning their calcium and PTH levels are normal. In these cases, the diagnosis is made only after a surgeon removes a neck lump that was found incidentally on imaging or because it was causing compression symptoms.

## Clinical Presentation: How Doctors Suspect Parathyroid Carcinoma

Distinguishing parathyroid carcinoma from the far more common benign parathyroid adenoma is genuinely difficult before surgery. The typical clinical picture of PC includes symptoms related to moderate or severe hypercalcemia:

- Nausea, vomiting, dehydration, and constipation
- Signs of target organ damage — nephrocalcinosis (calcium deposits in the kidneys), kidney stones, and impaired kidney function in up to **80%** of patients
- Manifestations of very high PTH levels: osteitis fibrosa cystica (bone disease with cysts), subperiosteal bone resorption, a “salt-and-pepper” appearance on skull x-rays, and bone loss of up to **90%**

At the physical examination, a doctor might feel a neck lump, or a patient might have laryngeal nerve palsy (hoarseness or voice changes). Distant metastases — most commonly to the lungs, bone, liver, and cervical lymph nodes — occur late in the disease course and are responsible for the intractable hypercalcemia that ultimately becomes life-threatening.

Several clinical and laboratory findings should raise suspicion of PC, including:

- Male sex
- A palpable neck mass and/or laryngeal nerve palsy
- Moderate-to-severe hypercalcemia — serum calcium generally above **14 mg/dL** and/or ionized calcium above **1.77 mmol/L**

- Very high PTH levels — more than **3 to 10 times** the upper limit of normal

Ultrasound features that suggest PC include:

- Parathyroid gland size greater than **3 cm**

- A heterogeneous cystic structure
- Irregular borders and calcifications
- Signs of infiltration and suspicious vascularity
- Marked adhesion to (or infiltration of) adjacent structures at surgical exploration

One retrospective ultrasound study of 69 PHPT cases (8 PC and 61 benign parathyroid lesions larger than 15 mm) found that local infiltration and calcification each had a **100% positive predictive value** for PC — meaning when either feature was present, the lesion was always malignant. A more recent similar study found that a tumor size above **2.05 cm** and tumor infiltration were independent markers of PC.

Conventional parathyroid imaging is otherwise of limited value for the preoperative diagnosis of PC unless there is clear evidence of local invasion or metastases. For example, 99mTc-sestamibi scans are not very helpful, though PC does tend to retain the tracer longer than benign lesions. When doctors strongly suspect PC, they may use **4-dimensional computed tomography (4DCT)** or magnetic resonance imaging (MRI) with gadolinium contrast to look for invasion into surrounding structures.

A retrospective study of 20 patients with PC found that the sensitivity of any single imaging technique — neck ultrasound, 4DCT, or 99mTc-sestamibi SPECT-CT — was approximately **80%**. Combining all three techniques raised sensitivity to **95% or higher**.

PET/CT with 18F-FDG is useful for staging, monitoring treatment response, and detecting recurrences in many cancers, but published experience in PC is limited. One important warning: **brown tumors** (the bone lesions caused by severe hyperparathyroidism) are very metabolically active and show up strongly on 18F-FDG-PET/CT. They can easily be misdiagnosed as bone metastases, so doctors must interpret these scans carefully.

In recent years, 18F-choline PET/CT has become an increasingly useful tool for finding hyperfunctioning parathyroid glands. Experience in PC is still limited to case reports, but it has successfully detected recurrent disease in several published cases.

Finally, the authors strongly advise against **preoperative fine-needle aspiration (FNA)** of a suspected parathyroid lesion. FNA cannot reliably distinguish a benign from a malignant tumor, and — most importantly — it can cause tumor rupture and **seeding**, meaning cancer cells can spread along the needle track and contaminate surrounding tissues.

## Perioperative Management: Preparing Patients with Dangerous Calcium Levels for Surgery

Patients with mild hypercalcemia — serum calcium below **12 mg/dL** — do not need specific preoperative treatment. The situation is different for patients with severe hypercalcemia, which is often accompanied by anorexia, nausea, vomiting, and nephrogenic diabetes insipidus (a condition where high calcium prevents the kidneys from concentrating urine, leading to extreme dehydration and reduced kidney function).

The first goal is to correct volume depletion. Doctors typically start with intravenous saline, possibly combined with subcutaneous calcitonin (a hormone that quickly lowers calcium). The rate of fluid administration depends on how severe the hypercalcemia is. Loop diuretics (such as furosemide) may be added in patients at risk of fluid overload once their volume status has been restored.

These measures — intravenous fluid with or without diuretics — typically reduce serum calcium by **1 to 2 mg/dL within a few hours**. However, this effect is only temporary unless stronger medications are started. Potent intravenous bisphosphonates (pamidronate or zoledronate) or **denosumab** (a monoclonal antibody that blocks bone breakdown) are used to get more sustained calcium lowering.

Anesthesiologists also need to be aware of the complications of moderate-to-severe hypercalcemia during surgery. High calcium levels can affect the blood clotting system, trigger heart arrhythmias, and interfere with non-depolarizing muscle relaxants (medications used to temporarily paralyze muscles during anesthesia).

## Surgical Approach: Why the First Operation Matters Most

Complete surgical removal of the tumor at the initial operation offers the best chance of cure. The gold standard procedure is **en bloc resection** — removing the tumor in one piece along with the ipsilateral thyroid lobe (the thyroid on the same side), the surrounding involved structures, and clear margins, all without spilling tumor cells.

During surgery, certain findings may alert an experienced endocrine surgeon to cancer:

- A firm, gray-white lesion (as opposed to the soft, reddish-brown appearance of a benign adenoma)
- A thick fibrous capsule and dense adhesions to surrounding structures

The following principles guide surgical decision-making:

1.
**En bloc resection reduces recurrence and metastasis risk.** This approach generally has a higher success rate, although some studies have not shown a clear mortality or recurrence benefit from wider resections.
1.
**The recurrent laryngeal nerve** (the nerve that controls the vocal cords) should be preserved unless the tumor has grown completely around it.
1.
**Lymph node metastases** are found in up to **19%** of PC cases, and are more common when the tumor is larger than 3 cm. Removing lymph nodes that are visibly involved is justified, but there is not enough evidence to recommend routine preventive (prophylactic) removal of all nearby lymph nodes.

When a patient has already had a more limited first surgery and the pathology report later reveals parathyroid carcinoma, the question is whether to go back. If there was extensive vascular and capsular invasion and/or persistent hypercalcemia after surgery, further surgery should be performed as soon as possible. If calcium and PTH levels are normal after the initial surgery, the decision is more personalized. A test called **parafibromin immunohistochemistry** (staining the tumor tissue to see whether the parafibromin protein is present) can help guide this decision:

- If parafibromin staining is **negative** (the protein is absent), this suggests a more aggressive tumor, and revision surgery with en bloc resection should be considered.
- If parafibromin staining is **positive** (the protein is present), further surgery might be avoided — though the authors note that long-term studies are needed to confirm that this more conservative approach is safe.

There is also a specific question about how to manage family members of a patient who has PC with a germline CDC73 mutation. The current expert recommendation is **not** to perform prophylactic parathyroidectomy (removing the glands before disease develops) in healthy gene carriers. Instead, the recommended approach is:

1. Perform a bilateral neck exploration to identify all four parathyroid glands.
1. Remove only the glands that look macroscopically abnormal.
1. Monitor gene carriers regularly for the development of parathyroid, kidney, jaw, and uterine problems.

## Pathological Diagnosis: How the Lab Confirms Cancer

A definitive diagnosis of parathyroid carcinoma requires at least one of the following definite signs of malignancy, as established by the **World Health Organization (WHO)**:

- Unequivocal neoplastic infiltration of adjacent tissues
- Lymphovascular invasion (cancer cells inside lymphatic or blood vessels attached to the vessel wall, usually with associated blood clots)
- Perineural invasion (cancer cells around or into nerves)

Other findings — strict adherence to surrounding structures, marked fibrosis with collagenous septa, or increased mitotic activity — may also be seen in PC, but these are *not* specific to malignancy. They can also appear in benign lesions and in **atypical parathyroid tumors** (lesions with concerning features but no definite signs of invasion), which the 2022 WHO classification now calls “atypical parathyroid tumors.”

Foci of coagulative necrosis (areas of dead tumor tissue) are more commonly seen in high-grade tumors, but necrosis alone is not considered a hallmark of malignancy in parathyroid pathology. It must be distinguished from harmless causes of dead tissue, such as spontaneous infarction (loss of blood supply) or changes after a fine-needle aspiration.

Most PCs show solid or trabecular growth patterns, though follicular, spindle cell, and even carcinosarcomatous patterns occasionally occur. Nuclear atypia — enlarged, hyperchromatic (darkly stained), or bizarre-looking nuclei — can also be seen in benign adenomas and is not diagnostic of cancer on its own.

Pathologists use features like cellular pleomorphism (cells looking very different from one another), necrosis, and mitotic activity to classify PC as **low-grade** or **high-grade**:

-
**High-grade PC** typically shows pleomorphic nuclei, prominent nucleoli, coagulative necrosis, abnormal mitoses, and/or an increased proliferative index.
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**Mild nuclear enlargement** without necrosis or elevated mitotic activity is not enough to diagnose PC.

The **Ki-67 index** (a measure of how quickly cells are dividing) is a useful test. A Ki-67 index above **5%** is usually found in parathyroid carcinoma, while a lower score is common in both adenomas and atypical parathyroid tumors. Because of this overlap, the 2022 WHO classification strongly encourages the routine use of Ki-67 staining in parathyroid pathology.

The WHO also emphasizes the use of **parafibromin immunohistochemistry**. This test is less expensive than gene sequencing and helps predict CDC73 mutations. When there is a complete loss of parafibromin staining in the nucleus, the tumor is classified as “**parafibromin-deficient**.”

To standardize reporting and improve patient care, the **International Collaboration on Cancer Reporting (ICCR)** has proposed a uniform pathology report. Core elements include the parathyroid gland’s weight, size, and tumor grade — including whether there is necrosis, the mitotic count, and whether there is perineural or lymphovascular invasion. The ICCR also recommends Ki-67 and parafibromin staining on all cases.

Finally, the **American Joint Committee on Cancer (AJCC) eighth edition** of cancer staging classifies PC based on local extension (how far the tumor has grown into surrounding tissues) and the presence of distant metastases.

## Germline Mutation Testing: The Genetics of Parathyroid Carcinoma

Because up to **30%** of apparently sporadic PCs are actually associated with inherited germline CDC73 mutations, the authors recommend that **all individuals diagnosed with PC be offered germline genetic testing**, wherever possible.

Most CDC73 mutations are point mutations or small insertions/deletions spread throughout the gene; large deletions or insertions are rare.

Why does this matter for patients?

- Patients with a confirmed germline CDC73 mutation should be monitored closely after surgery for early detection of local recurrence, new distant metastases, and the possible development of disease in other parathyroid glands.
- Regular surveillance is also recommended for other HPT-JT-related conditions, including kidney lesions, jaw tumors, and uterine tumors.
- Genetic testing of first-degree family members (parents, siblings, children) is recommended. Family members who carry the mutation should be monitored to catch disease early, while those who test negative can be reassured and spared unnecessary medical surveillance.

For patients who have persistent or recurrent disease that cannot be surgically removed and who test negative for CDC73 mutations, the authors suggest considering **next-generation sequencing** of the tumor. This approach looks for mutations in other genes that might be targeted by newer, specific therapies.

## Key Red Flags: Factors That Raise Suspicion of Parathyroid Carcinoma

For endocrinologists and endocrine surgeons, certain findings in a patient with primary hyperparathyroidism should immediately raise concern for parathyroid carcinoma. These include:

- The patient is **male** (since benign PHPT is far more common in women).
- The patient is relatively **young** (under 50).
- Serum calcium is very high (**above 14 mg/dL**).
- PTH levels are extremely elevated (**more than 3–10 times** the upper limit of normal).
- The patient has had **kidney stones, kidney calcification, or impaired kidney function**.
- The patient has significant **bone disease**, including brown tumors or severe bone loss.
- There is a **palpable neck mass** or vocal cord paralysis.
- Ultrasound shows a **large tumor (over 2–3 cm)**, with irregular borders, calcifications, or signs of invasion into surrounding tissue.
- At the time of surgery, the lesion is **firm, gray, and densely adherent** to the thyroid gland and other neck structures.

## Limitations: What the Medical Community Still Doesn’t Know

It is important for patients to understand that parathyroid carcinoma remains a poorly understood disease in many respects.

**First, there is no reliable preoperative test.** No blood marker, imaging finding, or biopsy result can definitively diagnose PC before surgery in most cases. The diagnosis often only becomes clear after a pathologist examines the removed tissue and finds definitive invasion.

**Second, many features of the disease overlap with benign conditions.** Atypical parathyroid tumors can look similar under the microscope, and even experienced pathologists can struggle to classify them. The Ki-67 index helps, but there is overlap between benign and malignant tumors.

**Third, the genetic picture is incomplete.** While CDC73 mutations explain most cases, mutations in other genes are only beginning to be understood. The long-term behavior of tumors with different genetic profiles is still being studied.

**Fourth, treatment for recurrent disease is limited.** Surgery is the mainstay of treatment, and repeated operations are often needed, but when the disease is no longer operable, medical therapy mainly focuses on managing hypercalcemia — the dangerous high calcium levels — rather than curing the cancer itself. Targeted therapies have shown promise in only a few reported cases.

**Fifth, the benefit of wider surgery is debated.** Although en bloc resection is generally recommended, some studies have not found a clear survival advantage compared with more limited resection. This reflects the rarity of the disease and the difficulty of conducting large clinical trials.

## Recommendations: What Patients Should Do

Based on this review, here is what patients and their families should keep in mind:

1.
**Seek an experienced surgical team.** Parathyroid carcinoma is so rare that outcomes are significantly better when the initial surgery is performed by a surgeon experienced in parathyroid disease. The first operation offers the best chance of cure.
1.
**Ask about genetic testing.** If you have been diagnosed with PC, talk to your doctor about germline CDC73 testing. The results can guide your follow-up, your family’s screening, and even treatment decisions.
1.
**Stay consistent with follow-up.** Even after successful surgery, the recurrence rate is **40% to 60%**. Regular monitoring of serum calcium and PTH levels, along with neck imaging when needed, can catch recurrences early when surgery is still possible.
1.
**Protect your kidneys and bones.** High calcium and PTH levels take a serious toll on these organs. Treating hypercalcemia aggressively, staying well hydrated, and monitoring kidney function and bone density are all essential parts of long-term care.
1.
**Involve family members in genetic counseling.** If a CDC73 mutation is found, first-degree relatives (parents, siblings, children) should be offered testing. Carriers need monitoring; non-carriers can be reassured.
1.
**Be wary of biopsy.** Fine-needle aspiration of a suspected parathyroid mass is not recommended because it cannot reliably distinguish benign from malignant disease and may spread cancer cells.
1.
**Consider a multidisciplinary team.** Given its rarity, PC should be managed in a center with expertise in endocrinology, endocrine surgery, pathology, and genetics working together.

The story of the 50-year-old patient in this review illustrates both the challenges and the possibilities. Despite a recurrence after his first surgery, he was able to undergo multiple surgeries over more than a decade, with his serum calcium levels tracked carefully from November 2010 through March 2022. Each time the disease returned, imaging — including CT, 18F-FDG PET/CT, and 18F-choline PET/CT — helped locate the lesions, and surgical removal helped bring his calcium levels back under control.

Parathyroid carcinoma is a serious and challenging disease, but it is manageable with the right team, the right timing, and a vigilant approach to follow-up. Knowledge is part of the treatment — and this patient’s story shows how far the medical field has come in understanding and treating this rare cancer.

## Frequently Asked Questions

### What is parathyroid carcinoma?

Parathyroid carcinoma is an extremely rare cancer of the parathyroid glands, which regulate blood calcium. It accounts for less than 1% of primary hyperparathyroidism cases. It usually causes severe high calcium levels, leading to kidney stones, kidney damage, and bone disease. It can be difficult to diagnose before surgery.

### What symptoms should make me suspect parathyroid carcinoma?

Red flags include severe hypercalcemia (calcium above 14 mg/dL), extremely high PTH levels, kidney stones or impaired kidney function, significant bone disease, a palpable neck mass, or vocal cord paralysis. Ultrasound may show a tumor larger than 2–3 cm with irregular borders, calcifications, or signs of invasion. Male sex and younger age also raise concern.

### Should I have genetic testing if I am diagnosed with parathyroid carcinoma?

Yes. Up to 30% of apparently sporadic parathyroid carcinomas are linked to inherited CDC73 mutations. The authors recommend offering germline genetic testing to all patients with parathyroid carcinoma. Results guide your follow-up, your family's screening, and treatment decisions. First-degree relatives should also be offered testing if a mutation is found.

### Is a biopsy safe for suspected parathyroid cancer?

No. The authors strongly advise against fine-needle aspiration (FNA) of suspected parathyroid lesions. FNA cannot reliably distinguish benign from malignant tumors and may cause tumor rupture and seeding, spreading cancer cells along the needle track. Diagnosis usually requires examination of the surgically removed tissue.

### What follow-up is needed after surgery for parathyroid carcinoma?

Even after successful surgery, recurrence rates are 40% to 60%. Regular monitoring of serum calcium and PTH levels, along with neck imaging when needed, is essential to catch recurrences early. Protect your kidneys with hydration and monitor kidney function and bone density. A multidisciplinary team is recommended.

### What is hungry bone syndrome after parathyroid surgery?

Hungry bone syndrome occurs when bones rapidly absorb calcium from the blood after being depleted by long-standing high PTH levels. It can cause dangerously low blood calcium. Treatment requires calcium and calcitriol (active vitamin D) for months. In one patient, this treatment was needed for 8 months to keep calcium stable.

## Source Information

This patient-friendly article is based on peer-reviewed research published in *The Journal of Clinical Endocrinology & Metabolism* (JCEM), 2024, Volume 109, pages 256–268.

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**Original title:** “Approach to the Patient With Parathyroid Carcinoma”
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**Authors:** Filomena Cetani, Elena Pardi, Liborio Torregrossa, Simona Borsari, Laura Pierotti, Elisa Dinoi, and Claudio Marcocci
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**Affiliations:** Unit of Endocrinology, University Hospital of Pisa, Pisa, Italy; Department of Clinical and Experimental Medicine, University of Pisa; Department of Surgical, Medical, Molecular Pathology and Clinical Area, University of Pisa
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**Publication details:** The Journal of Clinical Endocrinology & Metabolism, 2024, Vol. 109, No. 1, pp. 256–268. DOI: [10.1210/clinem/dgad455](https://doi.org/10.1210/clinem/dgad455)

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**Advance access publication:** August 2, 2023

This patient-friendly article was created by a medical writer to translate the original scientific publication into accessible language for patients and caregivers. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your doctor or endocrinologist with questions about your specific medical situation.


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