Oxyphil parathyroid adenoma: a malignant presentation of a benign disease

Digital spatial profiling of human parathyroid tumors reveals cellular and molecular alterations linked to vitamin D deficiency

Primary hyperparathyroidism (PHPT) is a common endocrine neoplastic disorder characterized by disrupted calcium homeostasis secondary to inappropriately elevated parathyroid hormone (PTH) secretion. Low levels of serum 25-hydroxyvitamin D (25OHD) are significantly more prevalent in PHPT patients than in the general population (1-3), but the basis for this association remains unclear. We employed a spatially defined in situ whole-transcriptomics and selective proteomics profiling approach to compare gene expression patterns and cellular composition in parathyroid adenomas from vitamin D-deficient or vitamin D-replete PHPT patients. A cross-sectional panel of eucalcemic cadaveric donor parathyroid glands was examined in parallel as normal tissue controls. Here, we report that parathyroid tumors from vitamin D-deficient PHPT patients (Def-Ts) are intrinsically different from those of vitamin D-replete patients (Rep-Ts) of similar age and preoperative clinical presentation. The parathyroid oxyphil cell content is markedly higher in Def-Ts (47.8%) relative to Rep-Ts (17.8%) and normal donor glands (7.7%). Vitamin D deficiency is associated with increased expression of electron transport chain and oxidative phosphorylation pathway components. Parathyroid oxyphil cells, while morphologically distinct, are comparable to chief cells at the transcriptional level, and vitamin D deficiency affects the transcriptional profiles of both cell types in a similar manner. These data suggest that oxyphil cells are derived from chief cells and imply that their increased abundance may be induced by low vitamin D status. Gene set enrichment analysis reveals that pathways altered in Def-Ts are distinct from Rep-Ts, suggesting alternative tumor etiologies in these groups. Increased oxyphil content may thus be a morphological indicator of tumor-predisposing cellular stress.

Giant versus regular parathyroid adenoma: A retrospective comparative study

Background

A fraction of Parathyroid Adenoma (PTA) is considered giant if they weigh more than 3.5 g. There is no clear consensus whether this subgroup has a distinct clinical or biochemical presentation that could have implications on PTA localization and management. In this study, we investigate the difference between regular and giant PTA patients regarding their clinical and laboratory findings as well as their postoperative outcomes.

Materials and methods

Clinical and PTA-related data were retrospectively retrieved from all patients undergoing parathyroidectomy from 2010 to 2019 at our hospital.

Results

A total number of 84 PTA (Females 76.2%) patients were included, of which 24 (28.6%) qualified as a giant with a mean weight of 7.86 g and the rest were regular adenomas (71.4%) with a mean weight of 1.45 g. Giant adenomas were more likely to present at a younger age compared to regular adenoma patients, (44.4 vs 50.8, P = 0.053, D = 0.470). Preoperative PTH levels were significantly higher in the giant PTA group (650.8 vs 334.2 pg/mL, P = 0.044, r = 0.22). Hospital stay was on average 1.6 days longer in giant PTA patients compared to regular PTA patients.

Conclusion

Giant PTA compromised a significant percentage of all adenomas, which was higher than what is reported in the literature and might reflect a delay in diagnosis and lack of screening tests. Both giant and regular adenomas seem to run a similar clinical course, yet biochemical abnormalities in PTH levels may have a predictive value for adenoma weight.

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Our sample included a high percentage of giant PTA compared to the literature. This might reflect a delay in diagnosis.

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Despite the difference in size, both giant and regular adenomas seem to run a similar clinical course, and the success of surgical treatment was found to be comparable.

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Biochemical abnormalities in PTH levels could have a potential role in predicting the weight and size of PTA.

[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.

Complementary role of parathormone washout test to 99mTc-MIBI parathyroid scintigraphy and histopathologic analysis of cell types in parathyroid adenomas

OBJECTIVE

Parathyroid scintigraphy (PS) can be negative or equivocal (N/E) in a considerable number of cases with highly suspicious clinical findings and biochemical results for parathyroid adenoma (PA). The aims of this study were to investigate the complementary role of parathormone washout test (PWT) to PS in patients with primary hyperparathyroidism (PHPT) and evaluate histopathologic aspects of PAs in comparison with PS results.

MATERIAL AND METHODS

Thirty-eight patients with PHPT referred for PS were included in the study. Seventeen patients had both scintigraphic and ultrasonographic findings concordant with PA (Group A). Twenty-one patients having N/E PS, but suspected lesions for PA on ultrasonography (US) formed Group B. PWT was performed for all patients and they underwent the surgical intervention. An adenoma was removed in all patients and the histopathologic cell characteristics were established.

RESULTS

The tumor size on US was larger in those patients whose adenomas were seen on the PS (P<.001). The percentages of chief (or principal), oxyphilic and clear cells in PAs were not statistically different between the groups. Serum parathormone level and PWT were not statistically significant between Group A and Group B (P=.095 and P=.04, respectively).

CONCLUSION

Although there is not a definitive threshold value, the sensitivity of PS increases with lesion size. While chief cell and oxyphilic cell content of PAs tend to deplete in N/E PS, clear cell rate increases substantially. Combining PS with both US and PWT increases the sensitivity of detection and localization of PAs.

Comparative proteomic analysis of chief and oxyphil cell nodules in refractory uremic hyperparathyroidism by iTRAQ coupled LC-MS/MS

SHPT is one of the most common complications of CKD-MBD. Recent studies indicate that oxyphil cell proliferation is related to SHPT progression, while not inhibited by current treatments. The aim of this study was to analyze the correlation between oxyphil cell and clinical indicators in SHPT, further explore the protein expression differences of oxyphil cell. Among 33 MHD patients, 84.8% patients have one or more oxyphil dominant glands and the overall oxyphil cells proportion was 39.5 ± 16.3%. Univariate correlation and multivariable linear regression model showed that oral calcitriol dosage and treatment duration were independently correlated to oxyphil cell ratio. Proteomic study showed that mitochondrial protein, protein synthesis, and cell cycle regulation were significantly altered in oxyphil cell nodules. DBP was downregulated in oxyphil nodules on protein level, which may contribute to calcitriol resistance by reducing vitamin D transport. Through KEGG and PPI network analysis, Wnt signaling, TGF-β, ubiquitin mediated proteolysis and cell cycle pathways were significantly enriched in oxyphil cell nodules. Among which, MIF-CUL1 axis was significantly increased. These results suggest that the limitations of vitamin D in SHPT treatment is closely related to oxyphil cell and may be attributed to the dysregulation of vitamin D transport and ubiquitin regulation of oxyphil cell.

SIGNIFICANCE

Secondary hyperparathyroidism in end stage renal patients is one of the major challenges nephrology field faces. Emerging data indicate that oxyphil cell may participate in the pathophysiology of secondary hyperparathyroidism, while both calcimimetics and vitamin D receptor activators treatments are underperformed in controlling oxyphil cell proliferation. In the present study, we validated that the proliferation of oxyphil cells is associated with calcitriol treatment, and discovered that oxyphil cell nodules were significantly different from chief cells nodules in protein expression of mitochondria, protein synthesis and cell cycle regulation. It is noteworthy that DBP was downregulated in oxyphil nodules on protein level and may therefore participate in the resistance of calcitriol therapy by reducing the vitamin D transport capacity. Wnt signaling, TGF-β, ubiquitin mediated proteolysis and cell cycle pathways were significantly enriched in oxyphil cell nodules, among which, MIF-CUL1 axis may play an important role in the regulation of oxyphil proliferation and calcitriol resistance through ubiquitin mediated proteolysis. These results suggest that calcitriol treatment has limitations in oxyphil cell predominant SHPT, which may be attributed to the dysregulation of vitamin D transport and ubiquitin regulation of oxyphil cell, and the influence of microenvironment in uremia status may be the underlying reason.

Oxyphil Cell Parathyroid Adenomas Causing Primary Hyperparathyroidism: a Clinico-Pathological Correlation

Oxyphil cell parathyroid adenomas (OPA) are considered to be an uncommon cause of primary hyperparathyroidism (PHPT), and were historically thought to be clinically silent. It has been our clinical impression that these adenomas present more often than previously thought and may manifest a more severe form of primary hyperparathyroidism than classical adenoma. The aim of this study was to describe the incidence and clinical presentation of OPA. An observational case-control study was undertaken. The study group comprised patients undergoing parathyroidectomy for PHPT where the final pathology confirmed OPA. The controls were made up of an age- and sex-matched group of patients having parathyroidectomy in the same time period where the final pathology confirmed a classical or non-oxyphil adenoma. OPA were defined as parathyroid tumours containing >75% oxyphilic cells. The OPA cases were obtained by reviewing all histopathology slides over an 11-year period (2002-12) where the reports contained the words 'oxyphil' or 'oxyphilic' parathyroid adenomas. These were then reviewed by two independent pathologists to confirm a diagnosis of OPA. The primary outcome measures were preoperative serum calcium and parathyroid hormone (PTH) levels. Secondary outcome measures were symptoms at presentation, accuracy of preoperative localization studies, parathyroid gland weight following surgery, and type of surgery undertaken. In the period 2002-2012, 2739 patients underwent surgery for PHPT. Following pathological review, 91 cases were confirmed as being OPA and formed the study group. A control group (n = 91) from the same period was selected following matching on the basis of age at presentation and sex. OPA were associated with higher preoperative serum calcium (10.84 versus 10.48 mg/dL, p < 0.001) and parathyroid hormone (139 versus 64 ng/L, p < 0.001). At presentation, a lower proportion of OPA cases had asymptomatic disease (15 versus 29%, p = 0.03). There was a trend toward a higher rate of renal calculi at presentation in the OPA group (9 versus 3%, p = 0.07). Preoperative ultrasound was less accurate in localization of OPA when compared with classical adenoma. The rate of minimally invasive surgery was 67% for OPA and 78% for the control group (p = 0.06). All patients were cured of hypercalcaemia at 6-month follow up. There was no significant difference in the weight of removed parathyroid tissue between the groups (868 mg for OPA versus 789 mg for the control group, p = 0.6). OPA are frequently symptomatic and are associated with higher preoperative serum calcium and parathyroid hormone levels than classical types of parathyroid adenomas. OPA are less likely to be localised on preoperative ultrasound examination.

18F-FDG PET/CT metabolic variability in functioning oncocytic parathyroid adenoma with brown tumors

A 29-year-old female patient exhibited a solitary neck mass, severe hypercalcemia, and multiple skeletal lytic lesions consistent with metastatic neoplastic disease. Fine-needle aspiration (FNA) cytology of the neck lesion indicated a follicular thyroid neoplasm. CT-guided bone biopsy was non-diagnostic. Subsequent 18F-FDG PET/CT examination demonstrated avid glucose uptake within the neck mass and diffuse bony lesions of variable metabolic activity. Repeat biopsy utilizing PET/CT guidance produced core tissue with classic histologic features of a brown tumor. Postoperative histology revealed an exclusively oncocytic parathyroid adenoma. Atypical radiotracer uptake of this rare functioning adenoma subtype is illustrated with discussion of improved procedural diagnostic yield utilizing PET/CT.

Functioning oxyphil parathyroid adenoma: a case report

Oxyphil parathyroid adenomas are rare and clinical features of patients with this entity are not well defined. We are presenting a case of primary hyperparathyroidism with marked elevation of parathyroid hormone (PTH) and near normal calcium levels, that underwent parathyroidectomy. Histopathology revealed an oxyphil adenoma which showed positivity for PTH on immunohistochemical staining. Post - operatively, there was a significant decline in both PTH and alkaline phosphatase levels. Benign oxyphil adenomas may mimic parathyroid carcinomas, both in terms of clinical features and tumour size; and they should be considered in the differential diagnosis of patients with primary hyperparathyroidism.

Unusual ¹⁸F-FDG PET/CT finding of an oxyphil parathyroid adenoma in a patient with Hodgkin's Lymphoma

Malignancy-associated hypercalcemia is a complication of advanced tumours that is associated to a poor prognosis. Thorough evaluation to establish its cause is essential because some patients may actually have undiagnosed primary hyperparathyroidism. We report a case of a patient affected by Hodgkin's Lymphoma and persistent hypercalcemia with an incidental (18)F-FDG PET/CT finding in the anterior neck region, not ascribable to malignancy, confirmed with (99m)Tc-sestamibi scintigraphy. It was removed by minimally invasive surgery. It was shown to be an oxyphil parathyroid adenoma localized in an unusual site.

Involvement of α-klotho, fibroblast growth factor-, vitamin-D- and calcium-sensing receptor in 53 patients with primary hyperparathyroidism

The presentation of patients with primary hyperparathyroidism is often atypical and ranges from normocalcemic, primary hyperparathyroidism to severe, symptomatic hypercalcemia. G-protein-coupled, calcium-sensing receptor (CaSR), vitamin D receptor (VDR), and fibroblast growth factor receptor (FGFR)/klotho complexes seem to be involved in the development of pHPT. Parathyroid glands from 53 patients with pHPT and normal parathyroid tissue from 7 patients were obtained during parathyroidectomy. Conventional detailed morphological and immunohistochemical analyses of parathyroid glands were performed after dividing each slide in a 3 × 3 array. From morphology, the number of lipocytes was significantly lower in parathyroid tissue glands in the pHPT group (p < 0.001). Protein expressions of klotho, CaSR, and VDR were significantly reduced in the pHPT compared with the control group (p = 0.004, p = 0.007, p < 0.001). No differences were seen between the two groups (p = 0.35) regarding expression of FGFR. Correlations between expression showed significant positively correlations between klotho and CaSR and FGFR and VDR. No correlations between klotho expression and serum calcium levels could be detected (R = -0.13, p = 0.66), but there were positive correlations between expressions of CaSR/serum phosphate and klotho/serum phosphate. Impaired protein expression of CaSR and VDR seem to be involved in the development of pHPT. The role of the FGFR/klotho-axis remains still unclear. Correlations between protein expression of CaSR and serum phosphate and klotho and serum phosphate levels could be detected. Whether these findings give new insights into the pathogenesis of the disease is yet unknown and has to be elucidated.

Aryl hydrocarbon receptor interacting protein (AIP) mutations occur rarely in sporadic parathyroid adenomas

CONTEXT

The molecular pathogenesis of primary hyperparathyroidism is still largely unknown. The aryl hydrocarbon receptor interacting protein (AIP) gene has a major role in the pathogenesis of familial isolated pituitary adenoma.

OBJECTIVE

We evaluated the involvement of the AIP gene in sporadic parathyroid adenomas.

PATIENTS AND DESIGN

We performed direct sequencing and multiplex ligation-dependent probe amplification analyses of the AIP gene in a large series of sporadic parathyroid adenomas. Loss of heterozygosity (LOH) at the AIP locus was studied, and aryl hydrocarbon receptor interacting protein immunostaining was also performed. In addition, alterations in the MEN1 gene were studied.

RESULTS

A somatic AIP mutation, substitution of arginine with glutamine at codon 304 (R304Q), was identified in 2 of 132 tumors. The mutation was germline in both cases despite the nonfamilial presentation. Heterozygous AIP large deletions were detected in 29 cases including 1 of the 2 mutated tumors, confirming a biallelic inactivation of the AIP gene. The AIP-mutated tumor with LOH showed decreased AIP immunostaining compared with normal parathyroid. LOH at the MEN1 locus, which often shared LOH at the AIP locus, was found in one third of tumors. Somatic MEN1 mutations were found in the 1 of the 2 AIP-mutated tumors and in 22 parathyroid adenomas. In addition, multiplex ligation-dependent probe amplification analysis revealed 1 large deletion of the MEN1 gene in 1 patient.

CONCLUSIONS

The AIP gene is rarely involved in parathyroid adenomas, but the germline nature of the mutations suggests that it might predispose to primary hyperparathyroidism. MEN1 gene alterations occur in a substantial proportion of sporadic parathyroid adenomas.

[Functioning oxyphil cell adenoma of parathyroid diagnosed with ureteral stone]

A case of oxyphil cell adenoma of parathyroid is presented. A 82-year-old woman complained of back pain. Left hydronephrosis, elevated serum calcium-parathyroid hormone and a nodule in the right neck suggested functioning parathyroid adenoma. Resected adenoma (15 mm x 10 mm x 5 mm) was exclusively composed of oxyphil cell. Production of parathyroid hormone by oxyphil cells was confirmed by immunohistochemistry. This case was found to be the smallest parathyroid oxyphil cell adenoma hitherto reported that caused urolithiasis.

Benign parathyroid adenoma presenting with unusual parathyroid crisis, anemia and myelofibrosis

Although the clinical symptoms of patients with benign parathyroid adenoma are usually nonspecific and benign, a malignant presentation of the benign disease may sometimes occur. Here, we report a case of a 58-year-old woman who presented with aggravated sacrum pain, general malaise, and polydipsia. Initial laboratory findings revealed hypercalcemia, normocytic anemia, and impaired renal function. Acute hypercalcemic crisis manifested and primary hyperparathyroidism was diagnosed together with myelofibrosis on account of the result of bone marrow biopsy. Excision of a parathyroid adenoma was performed, and the anemia and bone marker regressed later. These findings suggested that benign parathyroid adenoma may mimic the clinical presentation of parathyroid carcinoma, releasing excess parathyroid hormone and resulting in hyperparathyroid crisis. In addition, primary hyperparathyroidism can be associated with anemia and myelofibrosis.

Parathyroid Cancer

Parathyroid cancer is a rare endocrine tumor and an uncommon cause of HPT. Advances have been made to identify a promising molecular diagnostic marker for the disease. The use of accurate preoperative imaging modalities would undoubtedly facilitate its management by making an accurate preoperative diagnosis by assessing its invasiveness, and by searching for nodal or distant metastases. The effectiveness of the application of intraoperative PTH assay in the management of this rare condition remains to be seen. Radical surgical treatment offers the best chance of cure, but for patients who have refractory unresectable disease or metastases, the availability of more effective targeted medical therapy may palliate the debilitating symptoms of hypercalcemia, reduce its metabolic complications, and potentially improve survival.

Parathyroid lipoadenomas: a rare cause of primary hyperparathyroidism

OBJECTIVE

To review one institution's experience with parathyroid lipoadenomas and to report the associated clinical characteristics.

METHODS

We present a case series of parathyroid lipoadenomas. A parathyroid lipoadenoma was defined as a single adenoma with more than 50% fat on histologic examination in conjunction with primary hyperparathyroidism and resolution of hypercalcemia postoperatively. Patients who fulfilled the diagnostic criteria were identified from the surgical pathology files of the Mayo Clinic.

RESULTS

Five cases of parathyroid lipoadenomas, including 1 oxyphil lipoadenoma, were identified during the period from 1971 to 2001. The clinical picture of the study subjects resembled that of a typical patient with primary hyperparathyroidism. Parathyroid lipoadenomas were identified in 3 women (60%) and 2 men (40%), and only 1 patient presented with possible hypercalcemia-related symptoms of nephrolithiasis and hip fracture, leading to diagnosis. The mean serum calcium concentration was 11.1 mg/dL. Preoperatively, all study subjects had elevation of serum parathyroid hormone levels. Two of 3 patients (67%) had the tumor identified preoperatively by neck ultrasonography.

CONCLUSION

A parathyroid lipoadenoma is a rare cause of primary hyperparathyroidism. The clinical features of this pathologic entity are similar to those of the more common pathologic variants of parathyroid disease associated with primary hyperparathyroidism.