A retrospective analysis of molecular testing in cytologically indeterminate thyroid nodules with histologic correlation: Experience at a heterogenous multihospital system.

INTRODUCTION: Thyroid malignancy is one of the most common types of cancer in developed nations. Currently, fine-needle aspiration cytology (FNAC) is the most practical screening test for thyroid nodules. However, cytologically indeterminate samples comprise approximately 15%-30% of cases. These include cases classified as atypia of undetermined significance (AUS), follicular neoplasm (FN), and suspicious for malignancy (SFM). Indeterminate cases can be sent for molecular testing for more definitive classification to help guide management and prevent overtreatment of benign thyroid nodules. We conducted a retrospective review on molecular testing of indeterminate thyroid FNAC and reviewed subsequent histologic diagnoses in resection specimens to assess how molecular testing supported a diagnosis and its effect on clinical management of patients at our institution. METHODS: A retrospective chart review was performed on all thyroid FNAC specimens, corresponding molecular testing, and subsequent surgical resection specimens over a 6-year period. RESULTS: A total of 10,253 thyroid FNAC were performed in our hospital system during our study period, of which 10% (n = 1102/10,253) had indeterminate FNAC results. Molecular testing was performed in 16% (n = 178/1102) of indeterminate cytology cases. Genetic alterations were identified in 39% (n = 69/178) of the cases sent for molecular testing. The majority of cytologically indeterminate cases sent for molecular testing were follicular-patterned lesions and their corresponding resection specimens revealed mostly low grade follicular derived neoplasms (i.e., follicular adenoma, non-invasive follicular thyroid neoplasm with papillary-like nuclear features, and follicular variant of papillary thyroid carcinoma). Of the cases with identified genetic alterations, 75% (n = 52/69) were treated surgically. In cases with no genetic alterations identified, only 18% (n = 20/109) were treated surgically. DISCUSSION/CONCLUSION: Molecular testing on cytologically indeterminate thyroid nodules can help provide a more accurate risk of malignancy assessment in patients with lesions that are difficult to diagnosis based solely on FNAC morphology. The types of genetic alterations identified in the resected thyroid lesions were consistent with what has been previously described in the literature. Additionally, we found that in the patients with indeterminate thyroid FNAC with adjunct molecular testing, more than half did not undergo surgical resection. This finding emphasizes the value of adding molecular testing in patients, particularly when attempting to reduce unnecessary surgical intervention.

Persistent or Recurrent Disease in Thyroid Cancer Survivors Who Have Elevated Serum Antithyroglobulin Antibodies.

OBJECTIVE: Detection of residual differentiated thyroid cancer is important but difficult. A variety of imaging modalities and biochemical markers has been used with moderately good success. We hypothesized that elevated perioperative serum antithyroglobulin antibody (TgAb) levels would also be a predictive marker for persistent or recurrent thyroid cancer. METHODS: We performed a retrospective analysis of 277 differentiated thyroid cancer survivors divided into 2 groups: (1) those with low or normal serum TgAb (TgAb-) and (2) those with elevated serum TgAb (TgAb+). All patients were seen at one major academic medical center. Patients were followed for a median of 7.54 years. RESULTS: Patients in the TgAb+ group were more likely to have positive lymph nodes at initial surgery, to be assigned to a higher American Joint Committee on Cancer stage, and to have significantly higher incidence of persistent/recurrent disease. The higher incidence of persistent/recurrent cancer was significant under univariable and multivariable (including TgAb status, age, and sex) Cox proportional hazards model analysis. CONCLUSION: We conclude that individuals with elevated serum TgAb at the outset should be followed with a higher index of suspicion for persistent/recurrent thyroid cancer.

Calcium-sensing receptor autoantibody-mediated hypoparathyroidism associated with immune checkpoint inhibitor therapy: diagnosis and long-term follow-up.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have produced significant survival benefit across many tumor types. However, immune-related adverse events are common including autoimmune responses against different endocrine organs. Here, a case of ICI-mediated hypoparathyroidism focusing on long-term follow-up and insights into its etiology is presented. CASE AND METHODS: A 73-year-old man developed severe symptomatic hypocalcemia after the initiation of ipilimumab and nivolumab for the treatment of metastatic melanoma. Hypoparathyroidism was diagnosed with undetectable intact parathyroid hormone (PTH). Immunoprecipitation assays, ELISAs, and cell-based functional assays were used to test the patient for antibodies against the calcium-sensing receptor (CaSR). NACHT leucine-rich repeat protein 5 (NALP5) and cytokine antibodies were measured in radioligand binding assays and ELISAs, respectively. RESULTS: The patient's symptoms improved with aggressive calcium and vitamin D supplementation. At 3 years and 3 months since the diagnosis of hypoparathyroidism, PTH was still inappropriately low at 7.6 pg/mL, and attempted discontinuation of calcium and calcitriol resulted in recurrent symptomatic hypocalcemia. Analysis for an autoimmune etiology of the patient's hypoparathyroidism indicated that CaSR antibodies were negative before treatment and detected at multiple time points afterwards, and corresponded to the patient's clinical course of hypoparathyroidism. CaSR antibodies purified from the patient's serum activated the human CaSR. The patient was seronegative for NALP5 and cytokine antibodies, indicating that their hypoparathyroidism was not a manifestation of autoimmune polyendocrine syndrome type 1. CONCLUSION: The etiology of hypocalcemia is likely autoimmune hypoparathyroidism caused by the development of CaSR-activating antibodies that might prevent PTH release from the parathyroid.

Clinical Features in Differentiated Thyroid Carcinoma Stratified By Lymph Node Status.

OBJECTIVE: Cervical lymph node (CLN) metastases (mets) often occur in differentiated thyroid cancer (DTC), especially in the central compartment, and are a major predictor of local recurrence. We examined clinical endpoints in three groups of patients based on status of lymph node involvement: those with definite lymph node involvement (N1), negative lymph nodes (N0), and no lymph nodes resected (Nx). We correlated these endpoints with clinical and pathologic features of these patients. METHODS: Medical records of 261 patients with DTC who underwent thyroidectomy between 2006 and 2018 at our center were reviewed. Lymph node status of patients was categorized based on American Joint Committee on Cancer (AJCC) 8th edition criteria as N1, N0, and Nx. We performed statistical analysis to assess the differences among these groups, using one-way analysis of variance. When significant differences were found, pairwise comparisons were conducted among the three groups. Statistical significance was defined as 2-tailed P<.05 for all tests. RESULTS: There were significant differences among the groups in tumor multicentricity, tumor category/size, AJCC stage, and the presence of thyroglobulin auto-antibodies (TgAbs). There were no difference in age, gender, or histopathology. N1 patients had a higher incidence of multicentricity, larger tumor sizes, and were more likely to have elevated TgAbs. There were no significant differences between the N0 and Nx groups. CONCLUSION: This study shows that larger and multi-centric tumors are associated with increased likelihood of CLN mets in DTC. We suggest increased vigilance for CLN mets in tumors >2 cm, multicentric tumors, and patients with elevated TgAbs. ABBREVIATIONS: AJCC = American Joint Committee on Cancer; CLN = cervical lymph node; DTC = differentiated thyroid cancer; FTC = follicular thyroid cancer; mets = metastases; N0 = no cancer in any lymph nodes; N1 = cancer in a lymph node; N1a = cancer in a central compartment lymph node; N1b = cancer in a lateral neck lymph node; Nx = lymph nodes not resected or examined; PTC = papillary thyroid cancer; TgAb = thyroglobulin auto-antibody.