Apparently Nonfunctioning Metastases of Parathyroid Carcinoma

Case Report: Abdominal Lymph Node Metastases of Parathyroid Carcinoma: Diagnostic Workup, Molecular Diagnosis, and Clinical Management

Parathyroid carcinoma (PC) is an orphan malignancy accounting for only ~1% of all cases with primary hyperparathyroidism. The localization of recurrent PC is of critical importance and can be exceedingly difficult to diagnose and sometimes futile when common sites of recurrence in the neck and chest cannot be confirmed. Here, we present the diagnostic workup, molecular analysis and multimodal therapy of a 46-year old woman with the extraordinary manifestation of abdominal lymph node metastases 12 years after primary diagnosis of PC. The patient was referred to our endocrine tumor center in 2016 with the aim to localize the tumor causative of symptomatic biochemical recurrence. In view of the extensive previous workup we decided to perform [18F]FDG-PET-CT. A pathological lymph node in the liver hilus showed slightly increased FDG-uptake and hence was suspected as site of recurrence. Selective venous sampling confirmed increased parathyroid hormone concentration in liver veins. Abdominal lymph node metastasis was resected and histopathological examination confirmed PC. Within four months, the patient experienced biochemical recurrence and based on high tumor mutational burden detected in the surgical specimen by whole exome sequencing the patient received immunotherapy with pembrolizumab that led to a biochemical response. Subsequent to disease progression repeated abdominal lymph node resection was performed in 10/2018, 01/2019 and in 01/2020. Up to now (12/2020) the patient is biochemically free of disease. In conclusion, a multimodal diagnostic approach and therapy in an interdisciplinary setting is needed for patients with rare endocrine tumors. Molecular analyses may inform additional treatment options including checkpoint inhibitors such as pembrolizumab.

Functional giant parathyroid cyst with high concentration of CA19-9 in cystic fluid

A 63-year-old man was admitted to our hospital for the evaluation of hypercalcemia and anterior neck mass. Laboratory findings revealed hypercalcemia, hypophosphatemia, and hypercalciuria, as well as elevated serum levels of parathyroid hormone (PTH) and alkaline phosphatase. Computerized tomography and magnetic resonance images showed that the mass contained a cystic area. Parathyroid scintigraphy using either 99mTc-sestamibi alone or 201Tl-chloride in conjunction with 99mTc-pertechnetate for thyroid image subtraction showed uptake of the radioactivity into the cyst wall, suggesting that the mass originated from the parathyroid. Fine needle aspiration biopsy revealed that the cyst fluid was serous and bloody with extremely high concentrations of both PTH and CA19-9. The patient was diagnosed as primary hyperparathyroidism caused by parathyroid cyst and cervical exploration was performed. The cyst was dissected away along with the right lobe of the thyroid gland. After tumor removal, serum calcium and PTH levels were normalized. Histological study showed that the tumor possessed malignant potential with capsular invasion as well as moderate cellular atypia with trabecular pattern in arrangement. Parathyroid cells in the wall of the cystic tumor were immunostained positively for CA19-9, suggesting that CA19-9 in the cyst fluid was produced from the cells.

Parathyroid cancer: biology and management

A review of all reports in the literature of parathyroid carcinoma (PTC) was undertaken to define an optimal management strategy for this rare condition. PTC is uncommon and its etiology of PTC is largely unknown although patients with familial hyperparathyroidism, multiple endocrine neoplasia type 1 and irradiation to the head and neck are at increased risk for developing the disease. PTC occurs with equal frequency in both sexes and is usually diagnosed in the fifth decade. En bloc resection of the carcinoma and the adjacent structures in the neck is the surgical treatment and is associated with an 8% local recurrence rate and a long term overall survival rate of 89% (mean follow up 69 months). In contrast simple parathyroidectomy results in a 51% local recurrence rate and 53% long-term survival rate (mean follow up 62 months). Adverse prognostic factors for survival were initial management with simple parathyroidectomy alone, the presence of nodal or distant metastatic disease at presentation and non-functioning PTC.

Diagnosis and treatment of patients with parathyroid carcinoma: an update and review

Parathyroid carcinoma is a rare cause of primary hyperparathyroidism. However, to our best knowledge, at least 163 cases of functioning parathyroid carcinoma appeared in the English literature from 1981 to 1989. We summarize the available information obtained from the reports of those patients and compare it with previous descriptions of the disease. The etiology of parathyroid carcinoma is usually obscure, but the possibility of a radiation-induced malignant change in the parathyroid gland became evident in a few patients. Clinical manifestations, including age, sex, symptoms, and biochemical findings in this review were comparable to those in previous reviews. Noninvasive localization studies such as ultrasonography may offer a diagnostic clue to parathyroid carcinoma. Measurement of DNA content is a useful adjunct for making the histologic diagnosis of parathyroid carcinoma and prediction of the clinical outcome. Since the initial operation offers the best chance for cure, pre-operative suspicion and intra-operative recognition of the parathyroid cancer are essential. The initial operation should be en bloc resection of the tumor, avoiding rupture of the tumor capsule and spillage of tumor cells. As parathyroid carcinoma is a slow-growing but tenacious malignancy, repeated resection of local recurrent tumors or even distant metastases is effective for palliation of recurrent hypercalcemia and occasional cure. When hypercalcemia is refractory to surgical therapy or no recurrent tumor can be identified, other modalities of therapy must be considered. New drugs to control hypercalcemia by inhibiting bone resorption may hold promise in patients with recurrent parathyroid carcinoma.