Sleeping parathyroid tumor: rapid hyperfunction after removal of the dominant tumor

Chapter 11: Treatment modalities

Treatment modalities for primary hyperparathyroidism must take account of the expected benefits and risks of each treatment envisaged, before choosing the definitive option to be proposed to the patient. In this section, a Foreword puts in perspective the difficulties involved in choosing the criteria for a particular treatment method. Treatments are then considered one after the other: surgery, local destruction and medical management. This section does not consider therapeutic indications, which are dealt with in a section 9.

Near-Infrared Autofluorescence Signature: A New Parameter for Intraoperative Assessment of Parathyroid Glands in Primary Hyperparathyroidism

BACKGROUND

The success of parathyroidectomy in primary hyperparathyroidism depends on the intraoperative differentiation of diseased from normal glands. Deep learning can potentially be applied to digitalize this subjective interpretation process that relies heavily on surgeon expertise. In this study, we aimed to investigate whether diseased vs normal parathyroid glands have different near-infrared autofluorescence (NIRAF) signatures and whether related deep learning models can predict normal vs diseased parathyroid glands based on intraoperative in vivo images.

STUDY DESIGN

This prospective study included patients who underwent parathyroidectomy for primary hyperparathyroidism or thyroidectomy using intraoperative NIRAF imaging at a single tertiary referral center from November 2019 to March 2024. Autofluorescence intensity and heterogeneity index of normal vs diseased parathyroid glands were compared, and a deep learning model was developed.

RESULTS

NIRAF images of a total of 1,506 normal and 597 diseased parathyroid glands from 797 patients were analyzed. Normal vs diseased glands exhibited a higher median normalized NIRAF intensity (2.68 [2.19 to 3.23] vs 2.09 [1.68 to 2.56] pixels, p < 0.0001) and lower heterogeneity index (0.11 [0.08 to 0.15] vs 0.18 [0.13 to 0.23], p < 0.0001). On receiver operating characteristics analysis, optimal thresholds to predict a diseased gland were 2.22 in pixel intensity and 0.14 in heterogeneity index. On deep learning, precision and recall of the model were 83.3% each, and area under the precision-recall curve was 0.908.

CONCLUSIONS

Normal and diseased parathyroid glands in primary hyperparathyroidism have different intraoperative NIRAF patterns that could be quantified with intensity and heterogeneity analyses. Visual deep learning models relying on these NIRAF signatures could be built to assist surgeons in differentiating normal from diseased parathyroid glands.

Surgical Aspects of Primary Hyperparathyroidism

Parathyroidectomy (PTX) is the treatment of choice for symptomatic primary hyperparathyroidism (PHPT). It is also the treatment of choice in asymptomatic PHPT with evidence for target organ involvement. This review updates surgical aspects of PHPT and proposes the following definitions based on international expert consensus: selective PTX (and reasons for conversion to an extended procedure), bilateral neck exploration for non-localized or multigland disease, subtotal PTX, total PTX with immediate or delayed autotransplantation, and transcervical thymectomy and extended en bloc PTX for parathyroid carcinoma. The systematic literature reviews discussed covered (i) the use of intraoperative PTH (ioPTH) for localized single-gland disease and (ii) the management of low BMD after PTX. Updates based on prospective observational studies are presented concerning PTX for multigland disease and hereditary PHPT syndromes, histopathology, intraoperative adjuncts, localization techniques, perioperative management, "reoperative" surgery and volume/outcome data. Postoperative complications are few and uncommon (<3%) in centers performing over 40 PTXs per year. This review is the first global consensus about surgery in PHPT and reflects the current practice in leading endocrine surgery units worldwide. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Multiglandular Parathyroid Disease in Primary Hyperparathyroidism With Inconclusive Conventional Imaging

Inconclusive preoperative imaging is a strong predictor of multiglandular parathyroid disease (MGD) in patients with primary hyperparathyroidism (PHPT). MGD was investigated in a cohort of 17 patients with PHPT (mean age 64.9 years, total calcium 2.75 mmol/l and parathyroid hormone (PTH) 113.3 ng/l) who underwent 18F-fluorocholine PET/CT (FCH) imaging before surgery. The initial MIBI SPECT scintigraphy (MIBI) and/or neck ultrasound were not conclusive or did not localize all pathological parathyroid glands, and PHPT persisted after surgery. Sporadic MGD was present in 4 of 17 patients with PHPT (24 %). In 3 of 4 patients with MGD, FCH correctly localized 6 pathological parathyroid glands and surgery was successful. Excised parathyroid glands were smaller (p <0.02) and often hyperplastic in MGD than in single gland disease. In two individuals with MGD, excision of a hyperplastic parathyroid gland led to a false positive decline in intraoperative PTH and/or postoperative serum calcium. Although in one patient it was associated with partial false negativity, parathyroid imaging with FCH seemed to be superior to neck ultrasound and/or MIBI scintigraphy in MGD.

Surgical Management of Primary Hyperparathyroidism-Clinicopathologic Study of 1019 Cases from a Single Institution

BACKGROUND

Primary hyperparathyroidism (pHPT) is an endocrine disorder characterized by hypercalcemia and caused by the presence of disordered parathyroid glands. Parathyroidectomy is the only curative therapy for pHPT, but despite its high cure rate of 95-98%, there are still cases where hypercalcemia persists after this surgical procedure. The aim of this study was to present the results of a surgical treatment of patients due to primary hyperparathyroidism and failures related to the thoracic location of the affected glands.

METHODS

We present a retrospective analysis of 1019 patients who underwent parathyroidectomy in our department in the period 1983-2018.

RESULTS

Among the group of 1019 operated-on patients, treatment failed in 19 cases (1.9%). In 16 (84.2%) of them, the repeated operation was successful. In total, 1016 patients returned to normocalcemia.

CONCLUSIONS

Our results confirm that parathyreoidectomy is the treatment of choice for patients with primary hyperparathyroidism. The ectopic position of the parathyroid gland in the mediastinum is associated with an increased risk of surgical failure. Most parathyroid lesions in the mediastinum can be safely removed from the cervical access.

Familial isolated primary hyperparathyroidism associated with germline GCM2 mutations is more aggressive and has a lesser rate of biochemical cure

BACKGROUND

Hereditary primary hyperparathyroidism may be syndromic or nonsyndromic (familial isolated hyperparathyroidism). Recently, germline activating mutations in the GCM2 gene were identified in a subset of familial isolated hyperparathyroidism. This study examined the clinical and biochemical characteristics and the treatment outcomes of GCM2 mutation-positive familial isolated hyperparathyroidism as compared to sporadic primary hyperparathyroidism.

METHODS

We performed a retrospective analysis of clinical features, parathyroid pathology, and operative outcomes in 18 patients with GCM2 germline mutations and 457 patients with sporadic primary hyperparathyroidism.

RESULTS

Age at diagnosis, sex distribution, race/ethnicity, and preoperative serum calcium concentrations were similar between the 2 groups. The preoperative serum levels of intact parathyroid hormone was greater in patients with GCM2-associated primary hyperparathyroidism (239 ± 394 vs 136 ± 113, P = .005) as were rates of multigland disease and parathyroid carcinoma in the GCM2 group (78% vs 14.3%, P < .001 and 5% vs 0%, P = .04, respectively), but the biochemical cure rate was less in the GCM2 group (86% vs 99%, P < .001).

CONCLUSION

GCM2-associated primary hyperparathyroidism patients have greater preoperative parathyroid hormone levels, a greater rate of multigland disease, a lesser rate of biochemical cure, and a substantial risk of parathyroid carcinoma. Knowledge of these clinical characteristics could optimize the surgical management of GCM2-associated familial isolated hyperparathyroidism.

Aortopulmonary window parathyroid gland causing primary hyperparathyroidism in men type 1 syndrome

Primary hyperparathyroidism (HPT) is the most common endocrinopathy in Multiple Endocrine Neoplasia type 1 (MEN1) syndrome. Supernumerary and/or ectopic parathyroid glands, potentially causes of persistent or recurrent HPT after surgery, have been previously described. However, this is the first ever described case of ectopic parathyroid gland localized in the aortopulmunary window causing HPT in MEN1. After a consistent concordant pre-operative imaging assessment the patient, a 16 years old male affected by a severe hypercalcemia, underwent surgery. The parathyroid was found very deeply near the tracheal bifurcation, hidden by the aortic arch itself and for this reason not visible at the beginning of the dissection but only after being identified by palpation for its typical consistence. The intraoperative PTH decreased at normal level 10 min after removal of the ectopic gland. The patient remained with normal value of calcemia and PTH during the 10 months of follow-up.

Intraoperative parathyroid hormone assay-cutting the Gordian knot

BACKGROUND

Hyperparathyroidism is treated by surgical excision of the hyperfunctioning parathyroid gland. In case of adenoma the single abnormal gland is removed, while in hyperplasias, a subtotal excision, that is, three-and-a-half of the four glands are removed. This therapeutic decision is made intraoperatively through frozen section evaluation and is sometimes problematic, due to a histological overlap between hyperplasia and the adenoma. The intraoperative parathyroid hormone (IOPTH) assay, propogated in recent years, offers an elegant solution, with a high success rate, due to its ability to identify the removal of all hyperfunctioning parathyroid tissue.

AIM

To study the feasibility of using IOPTH in our setting.

MATERIALS AND METHODS

Seven patients undergoing surgery for primary hyperparathyroidism had their IOPTH levels evaluated, along with the routine frozen and paraffin sections.

RESULTS

All seven patients showed more than a 50% intraoperative fall in serum PTH after excision of the abnormal gland. This was indicative of an adenoma and was confirmed by histopathological examination and normalization of serum calcium postoperatively.

CONCLUSION

The intraoperative parathyroid hormone is a sensitive and specific guide to a complete removal of the abnormal parathyroid tissue. It can be incorporated without difficulty as an intraoperative guide and is superior to frozen section diagnosis in parathyroid surgery.

Multiplicity of hormone-secreting tumors: common themes about cause, expression, and management

CONTEXT

Multiplicity of hormone-secreting tumors occurs in a substantial portion of hormone-excess states. Multiplicity increases the difficulty of management and drives the selection of special strategies.

EVIDENCE ACQUISITION

This is a synthesis from publications about tumor development and expression, and also about types of clinical strategy for hormone-secreting tumors.

EVIDENCE SYNTHESIS

Comparisons were made between patient groups with solitary tumors vs those with multiple tumors. Major themes with clinical relevance emerged. Usually, tumor multiplicity develops from a genetic susceptibility in all cells of a tissue. This applies to hormone-secreting tumors that begin as either polyclonal (such as in the parathyroids of familial hypocalciuric hypercalcemia) or monoclonal tumors (such as in the parathyroids of multiple endocrine neoplasia type 1 [MEN1]). High penetrance of a hereditary tumor frequently results in bilaterality and in several other types of multiplicity. Managements are better for the hormone excess than for the associated cancers. Management strategies can be categorized broadly as ablation that is total, subtotal, or zero. Examples are discussed for each category, and 1 example of each category is named here: 1) total ablation of the entire tissue with effort to replace ablated functions (for example, in C-cell neoplasia of multiple endocrine neoplasia type 2); 2) subtotal ablation with increased likelihood of persistent disease or recurrent disease (for example, in the parathyroid tumors of MEN1); or 3) no ablation of tissue with or without the use of pharmacotherapy (for example, with blockers for secretion of stomach acid in gastrinomas of MEN1).

CONCLUSIONS

Tumor multiplicity usually arises from defects in all cells of the precursor tissue. Even the optimized managements involve compromises. Still, an understanding of pathophysiology and of therapeutic options should guide optimized management.