Concurrence of Primary Hyperparathyroidism and Metastatic Breast Carcinoma Affected a Parathyroid Gland

Abstract

This case illustrates that hyperparathyroidism caused by parathyroid hyperplasia was concurrent with metastatic breast cancer to a parathyroid gland without disseminated systemic metastasis. Although this case is very uncommon and it is not clear whether there is a relationship between breast cancer and primary hyperparathyroidism, that possibility should always be considered as the cause of hypercalcemia in patients with breast cancer.

Hypercalcemia in metastatic breast cancer unrelated to skeletal metastasis

“…10 There have been few reported cases of breast cancer metastasizing to a parathyroid gland. 5,8,11 Parathyroid adenomas were the recipients in three previously reported cases, and one case of four-gland hyperplasia with metastatic disease involving one of the hyperplastic glands was observed. 5,8,11 In two of these cases, the parathyroid involvement was the only evidence of dis- seminated disease, with the remaining showing widespread disease.…”

“…5,8,11 Parathyroid adenomas were the recipients in three previously reported cases, and one case of four-gland hyperplasia with metastatic disease involving one of the hyperplastic glands was observed. 5,8,11 In two of these cases, the parathyroid involvement was the only evidence of dis- seminated disease, with the remaining showing widespread disease. 5,8,11 The current case illustrates the importance of considering a second unrelated pathology in the setting of hypercalcemia in a patient with breast cancer.…”

“…Parathyroid hormone levels would be normal or elevated in the setting of primary hyperparathyroidism but suppressed with bony metastasis or humoral hypercalcemia of malignancy. 5 If the level of parathyroid hormone is inappropriately elevated, a parathyroid scan (Figure 2) should be performed to assess for an adenoma as well as ultrasonography (Figure 1) for anatomic localization.…”

“…5,8,11 In two of these cases, the parathyroid involvement was the only evidence of dis- seminated disease, with the remaining showing widespread disease. 5,8,11 The current case illustrates the importance of considering a second unrelated pathology in the setting of hypercalcemia in a patient with breast cancer. Hypercalcemia is a common complication of breast cancer, and primary hyperparathyroidism is one of the potential causes.…”

“…Renal cell cancer is the most frequent malignant recipient, and meningioma is the most frequent benign recipient. 5 Of note, endocrine tumours, including parathyroid tumours, were found to comprise 45% of recipient lesions, possibly because the high vascularity of endocrine tissue provides a good recipient bed for metastasis. 9 Tumour-to-tumour metastasis involving the parathyroid glands is considered rare; however, its true incidence is largely unknown, perhaps because parathyroid glands are not routinely assessed during autopsy.…”