An unusual ectopic location of a parathyroid carcinoma arising within the thyroid gland

Clinicopathological spectrum, management, and outcome of ectopic parathyroid carcinoma: Experience with 24 cases

PURPOSE

Ectopic parathyroid carcinoma (EPC) is a rare clinical entity with multiple diagnostic pitfalls, making surgical cures challenging. We assessed the clinicopathological spectrum and outcome of EPCs.

METHODS

In this retrospective cohort study, 24 EPCs were identified from 133 PC patients treated at a tertiary referral center. The relationship between clinicopathological findings and locations was analyzed.

RESULTS

The locations of EPCs were predominantly intrathyroidal (62.5%), followed by 16.7% in the mediastinum, 8.3% in the retropharyngeal space, 8.3% in the carotid sheath, and 4.2% in the upper neck. Intrathyroidal EPC patients experienced higher serum calcium (p = 0.020), a higher rate of vascular invasion (p = 0.040), and a slightly higher incidence of non-R0 initial resection (p = 0.092) than those in other ectopic locations. Intrathyroidal EPC patients also suffered a trend of higher upper aerodigestive tract (UAT) invasion rate (p = 0.070) and higher risks of distant metastasis (p = 0.037) than the other PC patients. The 5-year disease-free survival rate after surgery was slightly compromised at 41.5% in intrathyroidal EPC patients compared with 77.8% among those in other ectopic locations (p = 0.143) and 59.7% among the other PC patients (log-rank = 3.194; p = 0.074), though without statistical significance.

CONCLUSION

Intrathyroidal EPC might cause a more biochemically and invasively distinct PC picture compared with other PCs. Special caution should be exercised in the preoperative diagnosis and management of such cases.

Intrathyroidal parathyroid carcinoma: a case report and literature review

Parathyroid carcinoma is an uncommon endocrine malignancy comprising 0.5%–2% of patients with primary hyperparathyroidism. The probability of an intrathyroidal location is low (0.2%) and make preoperative suspicion and diagnosis challenging. Less than 20 cases of intrathyroidal parathyroid carcinoma have been reported. We introduce a case of intrathyroidal parathyroid carcinoma mimicking a suspicious thyroid nodule, and review the literature, with a focus on the role of adjuvant radiotherapy.

Synchronous intrathyroidal parathyroid carcinoma and thyroid carcinoma: case report and review of the literature

BACKGROUND

Parathyroid carcinoma is a rare endocrine malignancy, rarer when synchronous with a non medullary well differentiated thyroid carcinoma. Parathyroid carcinoma accounts of 0.005% of all malignant tumors and it is responsible for less than 1% of primary hyperparathyroidism. The intrathyroidal localization of a parathyroid gland is not frequent with a reported prevalence of 0.2%. Carcinoma of parathyroids with intrathyroidal localization represents an even rarer finding, reported in only 16 cases described in literature. The rare constellation of synchronous parathyroid and thyroid carcinomas has prompted us to report our experience and perform literature review.

CASE PRESENTATION

We herein report a case of a 63-years-old man with multinodular goiter and biochemical diagnosis of hyperparathyroidism. Total thyroidectomy with radio-guide technique using gamma probe after intraoperative sesta-MIBI administration and intraoperative PTH level was performed. The high radiation levels in the posterior thyroid lobe discovered an intrathyroidal parathyroid. Microscopic examination revealed a parathyroid main cell carcinoma at the posterior thyroidal left basal lobe, a classic papillary carcinoma at the same lobe and follicular variant of papillary carcinoma at the thyroidal right lobe. To the best of our knowledge, this is the first case documenting a synchronous multicentric non medullary thyroid carcinomas and intrathyroidal parathyroid carcinoma.

CONCLUSIONS

Our experience was reported and literature review underlining challenging difficulties in diagnostic workup and surgical management was carried out.

Intrathyroidal parathyroid carcinoma presenting as an asymptomatic hypercalcemia: a case report

INTRODUCTION

A 26-year-old female presented with severe hypercalcemia. She was asymptomatic. Blood analysis revealed high serum calcium (13 mg/dL = 3.25 mmol/L) and elevated intact parathyroid hormone (iPTH) levels (267.5 ng/L).

RESULTS

Ultrasonography showed a mixed solid-cystic nodule of 30 mm in the left thyroid lower lobe and a nodular lesion of 14 mm posterior of the thyroid upper pole suggestive for parathyroid adenoma. Sestamibi scan and magnetic resonance imaging (MRI) revealed hyperfunctioning parathyroid tissue posterior of the left thyroid upper lobe. During surgery, a 15 mm nodule in the usual location of the left superior parathyroid was resected. Intraoperative frozen section revealed normal parathyroid tissue and intraoperative PTH levels did not decrease. Left thyroidectomy was performed due to the large solid-cystic nodule. Intraoperative PTH levels normalized 10 min later. Pathologic examination revealed a 28 mm nodule in the lower thyroid pole compatible with a parathyroid carcinoma (PC). Due to positive margins, a completion thyroidectomy was performed. 5-year follow-up showed no recurrence.

CONCLUSIONS

PC is a rare entity comprising 0.5-2% of patients with primary hyperparathyroidism. Even more unusual is an intrathyroidal parathyroid gland (0.2%). Only a dozen cases of intrathyroidal PC have been reported. Our case is the second patient reported to be asymptomatic.

[99mTc]Sestamibi SPECT Can Predict Proliferation Index, Angiogenesis, and Vascular Invasion in Parathyroid Patients: A Retrospective Study

The aim of this study was to evaluate the possible association among sestamibi uptake and the main histopathological characteristics of parathyroid lesions related to aggressiveness such as the proliferation index (Ki67 expression and mitosis), angiogenesis (number of vessels), and vascular invasion in hyperparathyroidism patients. To this end, 26 patients affected by primary hyperparathyroidism subjected to both scintigraphy with [⁹⁹mTc]Sestamibi and surgery/bioptic procedure were retrospectively enrolled. Hyperfunctioning of the parathyroid was detected in 19 patients. Our data showed a significant positive association among the sestamibi uptake and the proliferation index histologically evaluated both in terms of the number of Ki67 positive cells and mitosis. According to these data, lesions with a higher valuer of L/N (lesion to nonlesion ratio) frequently showed several vessels in tumor areas and histological evidence of vascular invasion. It is noteworthy that among patients with negative scintigraphy, 2 patients showed a neoplastic lesion after surgery (histological analysis). However, it is important to highlight that these lesions displayed very low proliferation indexes, which was evaluated in terms of number of both mitosis and Ki67-positive cells, some/rare vessels in the main lesion, and no evidence of vascular invasion. In conclusion, data obtained on patients with positive or negative scintigraphy support the hypothesis that sestamibi can be a tracer that is capable of predicting some biological characteristics of parathyroid tumors such as angiogenesis, proliferation indexes, and the invasion of surrounding tissues or vessels.

Endocrine scintigraphy with hybrid SPECT/CT

Nuclear medicine imaging of endocrine disorders takes advantage of unique cellular properties of endocrine organs and tissues that can be depicted by targeted radiopharmaceuticals. Detailed functional maps of biodistributions of radiopharmaceutical uptake can be displayed in three-dimensional tomographic formats, using single photon emission computed tomography (CT) that can now be directly combined with simultaneously acquired cross-sectional anatomic maps derived from CT. The integration of function depicted by scintigraphy and anatomy with CT has synergistically improved the efficacy of nuclear medicine imaging across a broad spectrum of clinical applications, which include some of the oldest imaging studies of endocrine dysfunction.

Intrathyroidal parathyroid carcinoma mimicking a thyroid nodule in a MEN type 1 patient

A 59-year-old woman with classic manifestations of hyperparathyroidism associated with multiple endocrine neoplasia type 1 presented with a right adrenal mass and two pituitary microadenomas on imaging studies. For evaluation of hypercalcemia, (99m) Tc-MIBI scintigraphy was done and showed focal uptake at the thyroid level of the right anterior neck. Subsequent neck sonography showed several thyroid nodules, but there was no parathyroid tumor. Percutaneous fine-needle aspiration of the dominant thyroid nodule indicated a follicular nodule. After surgery, final histopathology revealed intrathyroidal parathyroid carcinoma. This case illustrates the difficulty in diagnosing parathyroid carcinoma via fine-needle aspiration.

Nuclear medicine imaging of endocrine neoplasms

Endocrine tumors are hormonally active benign or malignant neoplasms arising within endocrine organs or from specialized cells of the amine precursor uptake and decarboxylation system. The detection rate of these tumors is increasing as a result of sensitive biochemical tests and high-resolution diagnostic imaging. Medical imaging has become a key component in the diagnosis and staging of endocrine malignancies; however, despite the impressive advances in computed tomography (CT) and MRI, detection of small primary tumors and metastases continues to be a challenge. Functional imaging techniques use radiopharmaceuticals targeted at unique tumor cellular processes in order to provide sensitive and highly specific whole-body imaging. Functional imaging allows prediction of the efficacy of radionuclide or receptor-based therapies and surveillance after therapy. Advances in imaging have not been limited to radiopharmaceuticals. Hybrid scanner technology in the form of PET/CT and single photon emission computed tomography (SPECT)/CT, designed to combine functional images with anatomic maps, has further improved the diagnostic accuracy. High-resolution hybrid imaging when deployed with novel PET and SPECT radiopharmaceuticals has the potential to dramatically change, individualize, and optimize imaging plans based on the histological grade, degree of differentiation, and genetic profile of each patient's endocrine neoplasm.