Parathyroid Gland Involvement by Thyroid Cancer: Results from a Large Series of Thyroidectomies Performed in Two Italian University Hospitals and Review of the Literature

Abstract

Objectives.Parathyroid involvement by thyroid cancer (TC) has not been frequently investigated in thyroidectomy-based studies. We aimed to detect cases of parathyroid invasion by TC in a large series of thyroidectomies and to review the literature on this topic. Study Design. A 10-yr period database research was made from the files of the Section of Pathology of two Italian University Hospitals. Out of 22,310 thyroidectomies, 10 patients with parathyroid involvement by TC were found. Results. The 10 patients, 7 females and 3 males, aged 55 ± 14 years (range 34–76, median 56) had papillary thyroid carcinoma and accounted for 0.4% of subjects affected by all TCs and submitted to thyroidectomy. The tumor invaded perithyroid soft tissues in 6 patients and central neck (level VI) lymph nodes in 3. Parathyroid involvement by TC occurred by infiltration in 6 cases, extension through an intervening pseudocapsule in 1, and both patterns in 3. All patients are alive and disease free at 5.6 ± 3-yr follow-up. Conclusion. Limited to thyroidectomy series, our results and literature data suggest that parathyroid involvement by TC has a 0.4–3.9% incidence rate; mainly affects women in their sixth-seventh decade of life; is associated to a good prognosis, unless massive extrathyroid extension of TC occurs.

Parathyroid carcinoma: diagnosis and clinical implications

“…In addition to primary malignancies of the parathyroid (parathyroid carcinoma), secondary (metastatic or infiltrating) malignant neoplasms from various organs can also deposit in the parathyroid glands (35). Very recently, Shifrin et al highlighted the importance of considering metastatic disease in the parathyroid glands as these are often overlooked and discovered incidentally at autopsy or during surgery for primary hyperparathyroidism (13,14,35,(108)(109)(110)(111)(112)(113)(114). For instance, direct extension from thyroid carcinomainto the parathyroid glands may occur in up to 4% of patients with thyroid carcinoma (35,108,110).…”

“…Very recently, Shifrin et al highlighted the importance of considering metastatic disease in the parathyroid glands as these are often overlooked and discovered incidentally at autopsy or during surgery for primary hyperparathyroidism (13,14,35,(108)(109)(110)(111)(112)(113)(114). For instance, direct extension from thyroid carcinomainto the parathyroid glands may occur in up to 4% of patients with thyroid carcinoma (35,108,110). Most parathyroid glands are located within the thyroid pseudocapsule or within the thyroid gland, and intrathyroidal parathyroid carcinomas can mimic a variety of tumors including medullary thyroid carcinoma, thyroid paraganglioma, secondary (metastatic) neuroendocrine carcinoma and poorly differentiated thyroid carcinoma.…”

Papillary Thyroid Cancer Metastases to the Parathyroid Gland

“…Papi et al 6 found the most predominant form of spread was through direct invasion (6 of 10 cases). This is in keeping with our patient, seen in the pathological specimen ( Figures 2 and 3 ).…”

“…Six different series describing this phenomenon have been published; 1 from Greece, 3 1 from Saudi Arabia, 4 1 from Italy 6 and 3 from Japan. 5 , 7 These studies suggest a predominance in women; however, it must be noted that the sample size is very small.…”

“…Several studies have tried to define whether the presence of parathyroid gland metastasis has an impact on outcomes in thyroid cancer. In Papi et al 6 ’s review, all cases with parathyroid gland metastasis fell within the intermediate risk category for disease recurrence. 6 However, none of the patients in this study (n = 10) had a detectable thyroglobulin level after a mean of 5.6 years.…”