Role of calcium-sensing receptor, Galectin-3, Cyclin D1, and Ki-67 immunohistochemistry to favor in the diagnosis of parathyroid carcinoma

Diagnostic and Surgical Challenges in Parathyroid Neoplasia: An Extensive Analysis of a Single Endocrine Surgery Center Cohort of Patients

BACKGROUND

Parathyroid neoplasia is a heterogeneous group of tumors, including parathyroid adenoma (PA), atypical parathyroid tumors (aPTs), and parathyroid carcinoma (PC). Differential diagnosis, especially preoperatively, between parathyroid carcinoma and the other two entities is challenging. The purposes of this study were to highlight the main differences between different parathyroid tumors and to evaluate how combined PC suspicion and intraoperative adjuncts can influence surgical decision-making and outcome-related issues.

METHODS

We performed a retrospective study of a database of patients diagnosed with parathyroid tumors who underwent surgical treatment at our endocrine surgery referral center between June 2019 and July 2024. Demographic, clinical, biochemical, imaging, intraoperative, immunohistochemical, and follow-up data were analyzed.

RESULTS

A total of 83 cases were included in our study, divided for analysis into PA (n = 67), aPT (n = 9) and PC (n = 7) subgroups. The clinical profile of the cohort showed a significant difference (p < 0.05) between the PA, aPT, and PC subgroups regarding the presence of palpable tumors (0% vs. 11.11% vs. 14.29%), both bone and kidney involvement (14.93% vs. 44.44% vs. 85.71%), and extensive disease beyond bone and kidney involvement (4.48% vs. 44.44% vs. 71.43%). PTH levels over five times the normal value were present at significantly different rates (p < 0.001), with higher rates in the aPT and PC subgroups (55.56% and 85.71%, respectively) compared with the PA subgroup (7.46%). Also, a significant difference (p < 0.001) was observed when analyzing extreme albumin-corrected serum calcium elevations over 14 mg/dL, with much higher rates in the PC subgroup (71.43%) compared to PA (1.49%) and aPT (33.33%). On preoperative ultrasonography, a significantly higher number of PCs presented diameters ≥ 3 cm (p < 0.001), depth-to-width ratios (D/W) ≥ 1 (p = 0.003), suspicious delineation (p < 0.001), and suspicious echotexture features (p < 0.001), compared to PAs. On preoperative US performed by the surgeon, suspicious features for thyroid cancer were identified in five more patients compared to the four identified by the initial US evaluation, and all (10.84% of all patients) were confirmed on final histopathology as papillary thyroid cancers. Intraoperatively, a significant difference (p < 0.001) regarding parathyroid macroscopic suspicious features, including adhesions to the thyroid gland, was seen between subgroups. When analyzing only cases with en bloc resection, we found that, in all PC cases, a combined preoperative suspicion was present, and in five cases an intraoperative suspicion was raised. Immunohistochemical data showed significantly different median Ki-67 indices between subgroups (1, 2, and 5; p = 0.008) and a different parafibromin staining profile between PC and aPT. Regarding intraoperative neuromonitoring use, a significantly lower incidence of voice changes related to the external branch of the superior laryngeal nerve was observed in the monitoring vs. non-monitoring group (57.14% vs. 12.5%, p = 0.019).

CONCLUSIONS

Our findings confirm that, in a multimodal and combined diagnostic approach, early pre- and intraoperative PC suspicion can be raised in order to optimize surgical treatment and, thus, favorably influence the outcome. Utilizing all resources available, including intraoperative parathormone determination, laryngeal nerve neuromonitoring, and immunohistochemistry staining, can bring extra benefit to the management of these challenging cases.

Basic-Clinical Analysis of Parathyroid Cancer

Parathyroid cancer (PC) presents clinically as a case of hyperparathyroidism associated with local compression symptoms. The definitive diagnosis of PC is complex as it requires unequivocal criteria of invasion in postoperative biopsy. Given the difficulty in confirming the diagnosis of PC, attempts have been made to address this problem through the search for biomarkers, mainly using immunohistochemistry. Within this theme, the phenomenon of epithelial-mesenchymal transition and cancer stem cell markers have been scarcely studied; this could eventually help discriminate between a diagnosis of parathyroid adenoma or carcinoma. On the other hand, identification of oncogenes and tumor suppressing genes, as well as epigenetic markers such as miRNAs, lncRNAs, and circRNAs all play a crucial role in tumorigenesis and have enormous potential as diagnostic tools. Furthermore, proteomic-based and inflammatory markers have also been described as diagnostic aids for this uncommon neoplasm. This review presents a clinical approach to the disease, as well as providing a state-of-the-art analysis of basic biomarkers in diagnosis and future projections in this field.

Molecular and Clinical Spectrum of Primary Hyperparathyroidism

Recent data suggest an increase in the overall incidence of parathyroid disorders, with primary hyperparathyroidism (PHPT) being the most prevalent parathyroid disorder. PHPT is associated with morbidities (fractures, kidney stones, chronic kidney disease) and increased risk of death. The symptoms of PHPT can be nonspecific, potentially delaying the diagnosis. Approximately 15% of patients with PHPT have an underlying heritable form of PHPT that may be associated with extraparathyroidal manifestations, requiring active surveillance for these manifestations as seen in multiple endocrine neoplasia type 1 and 2A. Genetic testing for heritable forms should be offered to patients with multiglandular disease, recurrent PHPT, young onset PHPT (age ≤40 years), and those with a family history of parathyroid tumors. However, the underlying genetic cause for the majority of patients with heritable forms of PHPT remains unknown. Distinction between sporadic and heritable forms of PHPT is useful in surgical planning for parathyroidectomy and has implications for the family. The genes currently known to be associated with heritable forms of PHPT account for approximately half of sporadic parathyroid tumors. But the genetic cause in approximately half of the sporadic parathyroid tumors remains unknown. Furthermore, there is no systemic therapy for parathyroid carcinoma, a rare but potentially fatal cause of PHPT. Improved understanding of the molecular characteristics of parathyroid tumors will allow us to identify biomarkers for diagnosis and novel targets for therapy.

Immunohistochemical Profile of Parathyroid Tumours: A Comprehensive Review

Immunohistochemistry remains an indispensable tool in diagnostic surgical pathology. In parathyroid tumours, it has four main applications: to detect (1) loss of parafibromin; (2) other manifestations of an aberrant immunophenotype hinting towards carcinoma; (3) histogenesis of a neck mass and (4) pathogenetic events, including features of tumour microenvironment and immune landscape. Parafibromin stain is mandatory to identify the new entity of parafibromin-deficient parathyroid neoplasm, defined in the WHO classification (2022). Loss of parafibromin indicates a greater probability of malignant course and should trigger the search for inherited or somatic CDC73 mutations. Aberrant immunophenotype is characterised by a set of markers that are lost (parafibromin), down-regulated (e.g., APC protein, p27 protein, calcium-sensing receptor) or up-regulated (e.g., proliferation activity by Ki-67 exceeding 5%) in parathyroid carcinoma compared to benign parathyroid disease. Aberrant immunophenotype is not the final proof of malignancy but should prompt the search for the definitive criteria for carcinoma. Histogenetic studies can be necessary for differential diagnosis between thyroid vs. parathyroid origin of cervical or intrathyroidal mass; detection of parathyroid hormone (PTH), chromogranin A, TTF-1, calcitonin or CD56 can be helpful. Finally, immunohistochemistry is useful in pathogenetic studies due to its ability to highlight both the presence and the tissue location of certain proteins. The main markers and challenges (technological variations, heterogeneity) are discussed here in the light of the current WHO classification (2022) of parathyroid tumours.

CaSR expression in normal parathyroid and PHPT: new insights into pathogenesis from an autopsy-based study

PURPOSE

Calcium sensing receptor (CaSR), on the surface of normal parathyroid cells, is essential for maintaining serum calcium levels. The normal pattern of CaSR immunostaining remains undefined and is presumptively circumferential. Given the physiological variation in serum calcium, we postulated that CaSR expression could not be uniformly circumferential. Also, cytoplasmic expression has not been evaluated either in normal or pathological tissues. We studied normal parathyroid tissues derived from forensic autopsies and those rimming parathyroid adenomas for membranous and cytoplasmic CaSR immunoexpression. Results were compared with primary hyperparathyroidism (PHPT) to look for any pathogenetic implications.

MATERIALS AND METHODS

We evaluated 34 normal parathyroid tissues from 11 autopsies, 30 normal rims, 45 parathyroid adenoma, 10 hyperplasia, and 7 carcinoma cases. Membranous expression was categorized complete/incomplete and weak/moderate/strong; scored using Her2/Neu and Histo-scores; predominant pattern noted. Cytoplasmic expression was categorized negative/weak/moderate/strong; predominant intensity noted.

RESULTS

Normal autopsy-derived parathyroid tissues were Her2/Neu 3 + , but incomplete membranous staining predominated in 85%. Their immune-scores were significantly more than the cases (p <  < 0.05). The mean histo-score of normal rims was intermediate between the two (p <  < 0.05). Cytoplasmic expression was strong in all autopsy-derived tissues, weak/negative in hyperplasia (100%), moderate in 16% adenomas, and 43% carcinomas.

CONCLUSIONS

Normal autopsy-derived parathyroid tissues showed strong but predominantly incomplete membranous expression. Surface CaSR expression decreased in PHPT and is probably an early event in parathyroid adenoma, seen even in normal rims. Whether there is a defect in CaSR trafficking from the cytoplasm to the cell surface in adenoma and carcinoma needs further evaluation.

Parathyroid cancer: A systematic review of diagnostic biomarkers

INTRODUCTION

Parathyroid cancers are rare and difficult to distinguish from benign parathyroid tumours. Prediction of malignancy often relies on intraoperative assessment of invasion. Standard histology is also inadequate; especially in the absence of local invasion, lymph nodal disease and metastasis. The aim of this project was to systematically review published literature on potential bio-markers used for the diagnosis of parathyroid cancer.

METHODS

Pubmed, Web of Science and Medline databases were searched. Inclusion criteria included English language papers published after 1985 and reporting on biomarkers in human studies of parathyroid cancer and benign disease.

RESULTS

118 relevant papers were appraised; all were observational studies. At least 2 papers studied 8 serum, 4 urine and 27 tissue biomarkers on the diagnosis of parathyroid cancer. Of these, 5 serum and 13 tissue markers have been demonstrated in at least one study to be statistically different in benign and malignant disease. We present a synthesis of data for each biomarker and measures of diagnostic accuracy where possible.

CONCLUSIONS

Consideration should be given to the use of a panel of biomarkers to review patients with suspected parathyroid cancer. A profile including serum calcium and PTH levels and tissue expression of APC, Parafibromin, PGP9.5, Galectin 3 and Ki67 is proposed. Systematic Review Registration Number - CRD42019127833.

Intratumor heterogeneity in human parathyroid tumors

Parathyroid tumors are the second most common endocrine neoplasia after thyroid neoplasia. They are mostly associated with impaired parathormone (PTH) synthesis and release determining the metabolic and clinical condition of primary hyperparathyroidism (PHPT). PHPT is the third most prevalent endocrine disorder, mainly affecting postmenopausal women. Parathyroid benign tumors, both adenomas of a single gland or hyperplasia involving all the glands, are the main histotypes, occurring in more than 95% of PHPT cases. The differential diagnosis between benign and malignant parathyroid lesions is a challenge for clinicians. It relies on histologic features, which display significant overlap between the histotypes with different clinical outcomes. Parathyroid adenomas and hyperplasia have been considered so far as a unique monoclonal/polyclonal entity, while accumulating evidence suggest great heterogeneity. Intratumor parathyroid heterogeneity involves tumor cell type, as well as tumor cell function, in terms of PTH synthesis and secretion, and of expression patterns of membrane and nuclear receptors (calcium sensing receptor, vitamin D receptor, α-klotho receptor and others). Intratumor heterogeneity can also interfere with cell molecular biology, in regard to clonality, oncosuppressor gene expression (such as MEN1 and HRPT2/CDC73), transcription factors (GCM2, TBX1) and microRNA expression. Such heterogeneity is likely involved in the phenotypic variability of the parathyroid tumors, and it should be considered in the clinical management, though at present target therapies are not available, with the exception of the calcium sensing receptor agonists.

Investigation of effect of vitamin D receptor, calcium-sensing receptor and β-catenin on cutaneous squamous cell carcinoma

Background

Cutaneous squamous cell carcinoma (cSCC) is a malignant and invasive tumor which is originated from epidermis with a high incidence among non-melanoma skin cancers. The aim of this study was to determine whether vitamin D receptor (VDR), calcium-sensing receptor (CaSR) and beta catenin (β-catenin) proteins have an effect on cSCC.

Materials and methods

VDR, CaSR and β-catenin proteins in tissue samples of cSCC and control group were analyzed by immunohistochemistry (IHC) and Western blotting (WB) method. IHC findings were statistically evaluated.

Results

IHC staining density of VDR and β-catenin were higher in cSCC tissue samples than control. The difference between IHC staining density of VDR and β-catenin in the patient and the control groups were statistically significant (p = 0.021, p = 0.021, respectively), but not for CaSR (p = 0.237). While the VDR and β-catenin staining rates obtained by the IHC method could be supported by WB results, the WB bands for CaSR could not be shown.

Conclusion

The findings suggest that VDR and β-catenin may have an effect on the disease. Further research is required to better understand the role of VDR and β-catenin together on cSCC.