Parathyroid Carcinoma

Parathyroid Carcinoma

Mitchell Temple, MD

Table of Contents

Background
Presentation and Diagnosis
Treatment

Background

A Rare Malignant Tumor of the Parathyroid Glands

Epidemiology

  • Responsible for 1% of Primary Hyperparathyroidism (PHPT) Cases
  • Affects Both Genders Equally
  • Most Common in the Fifth Decade of Life

Etiology is Largely Idiopathic and Sporadic

Associated Familial Syndromes

  • Multiple Endocrine Neoplasia (MEN) Syndromes
  • Hyperparathyroidism-Jaw Tumor Syndrome (HPT-JT) – Associated with Parathyroid Carcinoma and Fibro-Osseous Tumors of the Jaw

Radiation Exposure is a Potential Risk Factor

Parathyroid Carcinoma 1

Presentation and Diagnosis

Clinical Presentation

  • Primary Hyperparathyroidism
  • Most are Functional with Markedly Elevated Calcium and Parathyroid Hormone (PTH)
    • Hypercalcemia Symptoms: Fatigue, Depression, Weakness, Bone Pain, Pathological Bone Fractures, Kidney Stones, and Gastrointestinal Upset
  • Palpable Cervical Mass if Large – Many are Not Palpable and Found Incidentally
  • Local Symptoms Including Compression from the Tumor or Evidence of Recurrent Laryngeal Nerve Paralysis

Diagnosis

  • Often Diagnosed on Pathology After an Initial Surgery – Concern Raised if Adherent and Invading the Thyroid with No Clear Plane on Initial Surgery
  • Labs Concerning for Malignancy:
    • Serum Calcium > 14.0 mg/dL
    • PTH > 3-10 x Normal Upper Limit
    • Renal or Skeletal Abnormalities Combined with the Above
    • Levels are Generally Significantly Higher than in Benign Causes of Hyperparathyroidism
  • Imaging:
    • Options: US, CT, MRI, and Sestamibi Scan
    • Used to Localize an Abnormal Gland and May Demonstrate Suspicious Findings (Irregular and Fixed to Adjacent Tissue)
  • FNA/Biopsy is Rarely Performed Due to Fear of Seeding the Tumor
  • Definitive Diagnosis is Made by Histopathological Examination of the Excised Tumor
  • Key Pathologic Features:
    • Capsular Invasion, Vascular Invasion, or Metastases
    • Cellular Atypia
    • Fibrous Trabeculae
    • Mitotic Figures

Parathyroid Carcinoma on CT 1

Treatment

Primary Treatment: Radical Parathyroidectomy (En Bloc Resection with Ipsilateral Thyroid Lobectomy)

  • The Primary Treatment for Localized Disease
  • Avoid Capsular Disruption to Avoid Tumor Seeding and Parathyromatosis
  • May Require Recurrent Laryngeal Nerve Resection if Clearly Invading
  • Consider Lymph Node Dissection if There is Concern for Nodal Involvement
    • No Need for Prophylactic Central or Lateral Lymph Node Dissection – High Morbidity with Low Risk of Metastases

Risk for Hypocalcemia After Resection – May Require Calcium and Vitamin D Supplementation

Patients Require Lifelong Monitoring with Regular Serum Calcium, PTH, and Imaging to Detect Recurrence or Metastasis

Adjuvant and Palliative Therapy

  • Consider Resection Even if Locoregional or Distant Metastases are Present and Resection Would Not Be Curative – Reducing Tumor Burden May Normalize Calcium and Provide Symptomatic Palliation
  • Medical Management: Calcimimetics, Bisphosphonates, and Calcitonin May Be Used to Manage Hypercalcemia and Decrease Systemic Effects
  • Radiotherapy: Reserved for Palliative Cases and Should Not Be Routinely Used Post-Operatively
  • Chemotherapy: Not Generally Used and Considered Ineffective in Parathyroid Carcinoma

Prognosis

  • 5-Year Survival: 85.5%
  • Recurrence Rates Remain Elevated – About 50%
  • Prognosis is Improved When the Tumor is Localized and Completely Resected Early

References

Cover: Nephron. Parathyroid Carcinoma. Wikimedia Commons. 2019. (License: CC BY-SA-4.0)

  1. Kim KM, Park JB, Bae KS, Kang SJ. Hungry bone syndrome after parathyroidectomy of a minimally invasive parathyroid carcinoma. J Korean Surg Soc. 2011 Nov;81(5):344-9. (License: CC BY-NC-3.0)
  2. Sippel R, Chen H. The Handbook of Endocrine Surgery. World Scientific; 2012.
  3. Byrd C, Kwartowitz G. Cancer, Parathyroid. Nih.gov. Published February 24, 2019.
  4. Wilhelm SM, Wang TS, Ruan DT, et al. The American Association of Endocrine Surgeons Guidelines for Definitive Management of Primary Hyperparathyroidism. JAMA Surgery. 2016;151(10):959.