Accurate minimally invasive parathyroidectomy for hyperparathyroidism relies on accurate parathyroid adenoma localization,Technetium-99m sestamibi scintigraphy (TC-99m MIBI scan) both planar and Single-Photon Emission Computed Tomography (SPECT) is useful in the diagnosis of parathyroid gland adenoma, with sensitivity rates of about 90% in Primary Hyperparathyroidism (PHPT) but significantly lower rates in secondary hyperparathyroidism, Currently Tc-99m MIBI scan is the imaging technique of choice for parathyroid adenoma localization . Ultrasound is very useful tool in this setting with or without TC-99m MIBI scan. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are less commonly used for preoperative localization, and reserved for cases of failed parathyroidectomy, for detection of suspected ectopic gland, or recurrent hyperparathyroidism. The spectrum of parathyroid disease demonstrated with Tc-99m MIBI scintigraphy includes eutopic disease, ectopic disease, solitary adenoma, double or multiple adenomas and other rare parathyroid pathology. However in some clinical cases parathyroid scan is negative and failed to visualise parathyroid adenoma, which is relatively rare in solitary parathyroid adenoma but common in dual parathyroid pathology or polyglandular disorders . We report a case with primary hyperparathyroidism in which the preoperative parathyroid adenoma localization with TC-99m MIBI parathyroid scan was successful and the patient underwent parathyroid adenoma excision with immediate normalization of parathyroid hormone. After two months the patient was diagnosed with recurrent hyperparathyroidism; further imaging with MRI revealed a well-defined oval shaped soft tissue mass within the right paratracheal region of right parathyroid gland, parathyroid scan demonstrated a new parathyroid uptake suggesting a second parathyroid adenoma. Patient underwent exploration with the removal of second parathyroid adenoma and subsequently patient improved the clinical symptoms along with normal calcium levels.
We report a case of 76-year old female who is known to have hypertension and paroxysmal atrial fibrillation well controlled on medications, was diagnosed as a case of primary PHPT based on the following laboratory findings: serum calcium (Ca++) 2.6 mmol/L (2.1-2.5 mmol/L), Phosphorus 1.0 mmol/L (0.9-1.5 mmol/L), PTH 355 ng/L (RR:15-65 ng/L) and vitamin D 80 nmol/L ( 62-199 nmol/L). Technitum-99 sestamibi scintigraphy showed a localized avid uptake in left lower neck that was thought to represent left inferior parathyroid adenoma (Figure 1A-C). In addition, clinical examination showed multi nodular goitre with euthyroid hormones. Thyroid ultrasound showed multiple bilateral thyroid nodules (Figure 1D), Fine Needle Aspiration (FNA) taken from the right thyroid lobe and was suspicious of papillary thyroid cancer. Patient underwent total thyroidectomy in addition to resection of 2 left parathyroid glands. Histopathology proved a moderate risk of papillary thyroid cancer with tall-cell variant and 0.9 cm in size, positive lymph vascular invasion with positive extra thyroid extension with positive extension to margin. The patient tolerated the surgery well, parathyroid hormone was checked and it was coming down. After two months the patient showed hypercalcaemic crisis with calcium of 4.2, phosphorus was 0.61. Neck MRI showed well defined oval shape soft tissue mass with the right paratracheal region and the expected location of right parathyroid gland (Figure 2A). Tc-99m sestamibi scan showed focal tracer retention in the area that corresponds to abnormality noted in the MRI (Figure 2B-D). Patient underwent neck dissection for right parathyroidectomy, PTH level prior to the excision was 595.7ng/L and post excision it was 38.7ng/L. The pathology report showed hyper cellular parathyroid gland suggesting parathyroid hyperplasia. The patient was discharged in a good condition.
Figure 1A: Early anterior planar image of Technium-99m sestamibi scan demonstrates intense tracer uptake in the region of the left thyroid lobe consistent with parathyroid adenoma (arrow).
Figure 1B: Delayed anterior planar image of Technium-99m sestamibi scan demonstrates intense tracer uptake in the region of the left thyroid lobe consistent with parathyroid adenoma (arrow).
Figure 1C: Coronal sagittal image of SPECT of the neck and upper thorax image show focal intense radiotracer uptake in the lower pole of left thyroid lobe consistent with parathyroid adenoma (arrow).
Figure 1D: Sagittal ultrasound scan shows a well-defined, heterogeneous, solid thyroid nodule in left thyroid lobe (arrow) that showed intranodular and peripheral vascularity on colour Doppler scan.
Coronal T2- weighted magnetic resonance imaging demonstrates T2-high signal intensity well defined soft tissue nodule in the right lower neck (arrow).
Figure 2B: Early anterior planar image of Technium-99m sestamibi scan shows a possible mild tracer uptake within the inferior region of the right thyroid lobe (arrow).
Figure 2C: Delayed anterior planar images of Technium-99m sestamibi scan shows persistent uptake within the inferior region of the right thyroid lobe suggestive of parathyroid adenoma (arrow).
Figure 2D: Coronal sagittal image of SPECT of the neck and upper thorax image shows intense focal radiotracer uptake in the lower pole of thyroid in keeping with parathyroid adenoma (arrow).