Large parathyroid adenomas: Potential mechanisms to reconcile adenoma size and disease phenotype

The polar vessel sign: insights from CT imaging analysis in Asian Indian primary hyperparathyroidism

PURPOSE

Data on the polar vessel sign (enlarged feeding vessel terminating in parathyroid lesions) on four-dimensional computed tomography (4D-CT) is limited. We performed a retrospective analysis to determine the prevalence, predictors, and adjunctive utility of polar vessel sign in pre-operative 4D-CT of patients with primary hyperparathyroidism (PHPT).

METHODS

One radiologist blinded to the patients' details reported the 4D-CT of eighty-four operated patients with histopathology-proven single-gland PHPT. Two protocols were used to obtain arterial-phase images: timed via bolus tracking (n = 41) or fixed at 20 s after contrast injection (n = 43).

RESULTS

Seventy-one patients were symptomatic for PHPT, with median serum calcium 12.1 mg/dL. On the arterial phase of 4D-CT, 88.1% of lesions had the polar vessel sign, including 7/9 asymptomatic patients, 6/6 parathyroid carcinomas, and 3/4 ectopic(1:mediastinum, 2:thyro-thymic ligament). Predictors of polar vessel sign were maximum lesion dimension (2.2 vs. 1.4 cm; P = 0.03), solid-cystic CT morphology (47.3% vs. none; P = 0.004), and bolus tracking-timed arterial phase (55.4% vs. none; P = 0.001). Of these, bolus tracking improved the polar vessel's visualization (100% vs. 76.7%; P = 0.001) independent of lesion dimension and solid-cystic morphology. The latter two predicted polar vessel sign in images obtained at a fixed interval (20 s). A significantly lower proportion of bolus tracking-timed scans had lesion percentage arterial enhancement (PAE) < 128.9% (2/41 vs. 9/43; P = 0.04). Even with suboptimal PAE, the polar vessel helped identify 9/11 lesions.

CONCLUSION

The polar vessel sign demonstrated an additive role to PAE during CT reporting. Bolus tracking is valuable in optimizing vessel and tumor arterial enhancement and is easily incorporated into parathyroid 4D-CT protocol.

A giant parathyroid adenoma: a case report

BACKGROUND

Primary hyperparathyroidism is an endocrine disease and a common cause of nonmalignant hypercalcemia, often discovered incidentally in asymptomatic patients. The case reported herein illustrates that significant hormonal imbalances can present with unexpectedly mild clinical manifestations.

CASE PRESENTATION

We describe a 47-year-old Caucasian male with two episodes of kidney stones and otherwise no symptoms of severe hypercalcemia. In our case, fasting emerged as a potential risk factor for the development of renal stones. The diagnosis was primary hyperparathyroidism. The intervention consisted of preoperative fluids and cinacalcet while awaiting surgery. Despite initial stability, the patient experienced a subsequent increase in ionized calcium and parathyroid hormone levels, becoming symptomatic with fatigue, tremors, and heart palpitations. This progression led to a diagnosis of a hypercalcemic crisis, and the plan was accelerated. An acute parathyroid scintigraphy and an ultrasound was performed and revealed a giant intrathoracic parathyroid adenoma. After surgical removal of the adenoma, he developed hungry bones and biochemical remission. The patient has received three extracorporeal shock wave lithotripsy treatments for a stone in the upper left kidney, but as of a computed tomography scan on 9 February 2024, the stone remains unchanged. Owing to the stone's resistance to extracorporeal shock wave lithotripsy and the absence of symptoms, no further treatment is planned. Endoscopic laser treatment (retrograde intrarenal surgery) is an option, but for now, the situation will be monitored.

CONCLUSION

This case report underscores that extremely elevated levels of calcium and parathyroid hormone along with a rare giant parathyroid adenoma may not necessarily present with symptoms indicative of a calcium crisis. Additionally, management of such rare giant parathyroid adenomas requires careful monitoring and a tailored approach to address potential postsurgical complications such as hungry bone syndrome.

Unusual clinical presentation of a giant parathyroid adenoma: A case report from Morocco highlighting the rare entity and atypical symptoms

Primary hyperparathyroidism (PHPT), an endocrine disorder most commonly caused by parathyroid adenoma (PTA), manifests with a diverse array of symptoms, reflecting the multisystem impact of parathyroid hormone: nephrolithiasis, peptic ulcer disease, psychiatric disorders, muscle weakness, constipation, polyuria, pancreatitis, myalgia, and arthralgia. Rarely do these PTA attain a significant size. PHPT is usually diagnosed through biochemical tests, and radiological imaging characterizes the adenoma. Serum 25-hydroxyvitamin D levels are useful in explaining the large adenoma size. Here, we report a rare case of a 60-year-old female from Morocco who presented with marked dyspnea due to a giant PTA.

Do large parathyroid adenomas increase the risk of severe hypercalcemia?

<b><br>Introduction:</b> Primary hyperparathyroidism (PHPT) is mainly caused by parathyroid adenoma (PA). Rare variants of PA, weighing >2.0-3.5 g are called "large" or "giant" adenomas and account for about 1.5% of all PA.</br> <b><br>Aim:</b> The aim of this study was to compare normal-sized and large parathyroid lesions identifying risk factors for severe hypercalcemia.</br> <b><br>Materials and methods:</b> 27 patients with PHPT and parathyroid lesion ≥2.0 cm3 (study group) were compared with 73 patients with PHPT and lesion < 2.0 cm³ (control group). In both groups, the majority were women (81.5% - study group, 90.5% - control group, gender ratios 4.4:9.1, respectively). The patients were examined preoperatively and postoperatively: PTH, creatine, calcium, and phosphate serum and urine concentrations, and calcidiol serum levels were assessed. Preoperative ultrasonography (US) was performed.</br> <b><br>Results:</b> Patients with larger parathyroid lesions had signifficantly higher PTH and calcium serum concentrations and lower serum phosphate and calcidiol concentrations. There were no statistically significant differences in the concentration of creatine in serum and urine, calciuria, or tubular reabsorption of phosphorus (TRP). US relatively underestimated the parathyroid volume by about 0.3-0.4 mL (10% in larger lesions and 43% in smaller ones).</br> <b><br>Conclusions:</b> Due to higher PTH and calcium levels, larger parathyroid adenomas may constitute a higher risk of severe hypercalcemia. In general, US underestimated the parathyroid volume.</br>.

Influence of Vitamin D Deficiency on Cyclin D1-Induced Parathyroid Tumorigenesis

Primary hyperparathyroidism (PHPT) is a common endocrinopathy for which several pathogenic mechanisms, including cyclin D1 overexpression, have been identified. Vitamin D nutritional status may influence parathyroid tumorigenesis, but evidence remains circumstantial. To assess the potential influence of vitamin D insufficiency/deficiency on initiation or progression of parathyroid tumorigenesis, we superimposed vitamin D insufficiency or deficiency on parathyroid tumor-prone parathyroid hormone-cyclin D1 transgenic mice. Mice were placed on diets containing either 2.75 IU/g, 0.25 IU/g, or 0.05 IU/g cholecalciferol, either prior to expected onset of PHPT or after onset of biochemical PHPT. When introduced early, superimposed vitamin D insufficiency/deficiency had no effect on serum calcium or on parathyroid gland growth. However, when introduced after the onset of biochemical PHPT, vitamin D deficiency led to larger parathyroid glands without differences in serum biochemical parameters. Our results suggest that low vitamin D status enhances proliferation of parathyroid cells whose growth is already being tumorigenically driven, in contrast to its apparent lack of direct proliferation-initiating action on normally growing parathyroid cells in this model. These results are consistent with the hypothesis that suboptimal vitamin D status may not increase incidence of de novo parathyroid tumorigenesis but may accelerate growth of a preexisting parathyroid tumor.