Incidental thyroid carcinomas. A retrospective study

Study of non-invasive follicular thyroid neoplasm: A borderline entity

BACKGROUND

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a newly added entity in the fourth edition of the WHO Classification of Tumors of Endocrine Organs (2017). It is regarded as a neoplasm with very low malignant potential, thus affecting further treatment of the patients.

AIMS

To study the recently diagnosed entity, NIFTP, as not many cases have been reported of the same.

MATERIALS AND METHODS

A retrospective analysis of all thyroid neoplasms received in the Department of Pathology of our institute over two years was done. Out of the 188 cases that we reported, 38 were of non-invasive follicular neoplasms.

RESULTS

Thirty-two patients were female, whereas six patients were male. Thirty-five patients presented with solitary thyroid nodule and the others had an ill-defined thyroid swelling. Thirty-four patients had normal thyroid profile while two patients each presented with hypothyroidism and hyperthyroidism.

CONCLUSION

It is crucial to carefully study the histopathological features of solitary thyroid swellings and correlate with clinical and radiological findings. The recently added diagnostic category of NIFTP helps clinicians prevent over-treatment of a group of low-risk thyroid tumors.

Incidental thyroid carcinoma in an endemic goiter area in Italy: histopathological features and predictors of a common finding

PURPOSE

The occurrence and histopathological features of incidental thyroid carcinoma (ITC) vary considerably among populations from different geographical regions. The aim of this study is to assess the prevalence and histopathological characteristics of ITC in patients who underwent thyroid surgery for apparently benign thyroid diseases in an endemic goiter area in Italy.

METHODS

A total of 649 consecutive patients (531 females and 118 males; mean age, 52.9 ± 11.0 years), who underwent thyroid surgery at the Endocrine Surgery Unit of the tertiary care "Renato Dulbecco" University Hospital (Catanzaro, Italy) in the period between years 2017 and 2022, were included in this retrospective study. A comprehensive histopathological examination was performed on surgically excised thyroid tissue. Logistic regression analysis was employed to identify potential predictors of ITC.

RESULTS

The histopathological examination revealed the presence of ITC in 81 patients, accounting for 12.5% of the total study population. The female to male ratio was found to be 6.4 to 1. Among the patients with ITC, 72 had papillary carcinoma (PTC), with 53 of these tumors being microcarcinomas (microPTC). Additionally, 5 patients had follicular thyroid carcinoma, 2 patients had low-risk follicular cell-derived thyroid neoplasms, 1 patient had an oncocytic carcinoma, and 1 patient had a medullary thyroid carcinoma. Logistic regression analysis demonstrated a significant association between female sex and incidental microPTC.

CONCLUSIONS

These findings provide further evidence of the common occurrence of ITC, typically in the form of microPTC, among individuals who undergo thyroid surgery for apparently benign thyroid diseases.

An Indeterminate for Malignancy FNA Report Does Not Increase the Surgical Risk of Incidental Thyroid Carcinoma

Incidental thyroid carcinomas (ITCs) are a fairly frequent finding in daily routine practice, with papillary thyroid microcarcinoma being the most frequent entity. In our work, we isolated incidental cases arising in thyroids removed for other cytologically indeterminate and histologically benign nodules. We retrospectively retrieved cases with available thyroid Fine Needle Aspiration (FNA, 3270 cases), selecting those with an indeterminate cytological diagnosis (Bethesda classes III−IV, 652 cases). Subsequently, we restricted the analysis to surgically treated patients (163 cases) finding an incidental thyroid carcinoma in 22 of them. We found a 13.5% ITC rate, with ITCs representing 46.8% of all cancer histologically diagnosed in this indeterminate setting. Patients received a cytological diagnosis of Bethesda class III and IV in 41% and 59% of cases, respectively. All ITC cases turned out to be papillary thyroid microcarcinomas; 36% of cases were multifocal, with foci bilaterally detected in 50% of cases. We found an overall ITC rate concordant with the literature and with our previous findings. The assignment of an indeterminate category to FNA did not increase the risk of ITCs in our cohort. Rather, a strong statistical significance (p < 0.01) was found comparing the larger size of nodules that underwent FNA and the smaller size of their corresponding ITC nodule.

Incidental thyroid carcinoma: Correlation between FNAB cytology and pathological examination in 1093 cases

OBJECTIVE

To investigate Incidental Thyroid Carcinoma (ITC) by comparing the results of Fine Needle Aspiration Biopsy (FNAB) cytology and the postoperative pathological findings.

METHODS

Data of 1479 patients who underwent total thyroidectomy were retrieved. Three hundred eighty-six patients were excluded due to insufficient data. Each surgical specimen studied received two histopathological diagnoses: the local diagnosis ‒ for the same area in which the FNAB was performed; and the final diagnosis, which includes a study of the entire surgical specimen.

RESULTS

A thousand and ninety-three patients were investigated. FNAB result was malignant in 187 patients, benign in 204, suspicious or indeterminate in 668 cases, and inconclusive in 34 cases. The prevalence of ITC was 15.1%. Most of the ITC in this series was less than 0.5 cm. The incidence of ITC was higher in Bethesda III (17.5% ITC) and IV (19% ITC) than in Bethesda II cases (1.5% false negatives and 9% ITC).

CONCLUSION

Although the incidence of false-negative results in Bethesda II nodules is only 1.5%, 9% of these patients had ITC in the thyroid parenchyma outside the nodule that underwent preoperative FNAB. The incidence of ITC in the same scenario was even higher in Bethesda III (17.5%) and Bethesda IV cases (19%). Ultrasonography-guided FNAB is an excellent method for the assessment of thyroid nodules. However, biopsy sites should be carefully selected. Despite the high incidence of incidentalomas, total thyroidectomy should not always be the treatment of choice due to its rare but potentially serious complications. The findings of the present study can assist future clinical decisions towards active surveillance strategies for the management of papillary thyroid carcinoma.

Klotho Inhibits Proliferation in a RET Fusion Model of Papillary Thyroid Cancer by Regulating the Wnt/β-Catenin Pathway

Purpose

We aimed to investigate the mechanisms of action on Klotho that underlie cancer development in RET fusion models of human papillary thyroid cancer (PTC).

Materials and Methods

Normal Nthy-ori 3-1 thyroid cells and two PTC cell lines (BHP10-3 and TPC-1), which were used as RET fusion models of PTC, were used to study Klotho. Klotho expression was analyzed by Western blotting. Klotho overexpression cell lines were constructed using the two types of PTC cells. Cell proliferation and apoptosis were assessed. Western blotting was used to detect the expression of proteins in the Wnt/β-catenin pathway. In addition, an activator and an inhibitor of the Wnt/β-catenin pathway were used to confirm that Klotho regulates the pathway in PTC cells. Mice were used to analyze the in vivo effect of Klotho on tumor growth and the Wnt/β-catenin pathway.

Results

In BHP10-3 and TPC-1 cells, Klotho expression was low. After Klotho overexpression, the cell proliferation was significantly suppressed and apoptosis was significantly increased (p<0.05). Wnt1, β-catenin, and CyclinD1 expression were also significantly decreased after Klotho overexpression (p<0.05). Administration of the Wnt/β-catenin pathway activator attenuated the effect of Klotho overexpression (p<0.05). In vivo, the tumor growth was suppressed, and apoptosis of the cancer cells in the tumors were increased after Klotho overexpression. However, injection of the Wnt/β-catenin pathway activator attenuated the effects of Klotho overexpression.

Conclusion

Klotho inhibits cell proliferation in RET fusion models of PTC by inhibiting the Wnt/β-catenin pathway, providing a potential target for developing treatment for PTC.

Clinical-pathological issues in thyroid pathology: study on the routine application of NIFTP diagnostic criteria

In 2017, the WHO classification of tumours of the endocrine organs established the criteria for a NIFTP diagnosis. The present paper considers some aspects that are still debated or unresolved: the real incidence and clinical meaning of multifocal/multinodular lesions, the biological behaviour of micro-NIFTP, the sprinkling phenomenon and the corresponding modifications to the FNA reporting systems based on changes to the ROM. Moreover, the paper suggests possible scenarios for the clinical-pathological management of this entity. From the initial 1470 cases, a group of 68 NIFTPs was recruited in a 9 year-long period. The average age at diagnosis was 55 years. The average diameter of the lesion was 1.7 cm (0.1 cm–10 cm). In 41 cases (60.1%), the lesion was inserted in the context of a multinodular background. In 12 cases, the diagnosis was incidental and the pre- operative FNA was performed on a different target. In 10 out of 68 cases, there was a multifocal NIFTP; in 14.7% of patients, PTC-like nuclear features showed sprinkling phenomenon. The cytological revision allocated 21 cases (49%) to the SIAPEC TIR3 indeterminate class and a nuclear score 2 or 3 were identified in 25 smears. Multifocality is part of the spectrum of NIFTPs, that can arise in a multinodular background with variable sizes from microscopic lesions to very large ones. Cytopathological criteria such as an evaluation of the nuclear score may help the pathologists in promoting a NIFTP diagnosis in the preoperative setting.

A cancer of undetermined significance: Incidental thyroid carcinoma

INTRODUCTION

The incidence of thyroid cancer is increasing which can be attributed in part to improved ultrasonography (US) methods and increased detection of incidental thyroid carcinomas (ITC). We aimed to compare ITC with nonincidental thyroid carcinomas (NITC) in this study.

METHODS

Retrospective analyses of 906 individual patients who were operated for benign and malignant thyroid disease and had a final histopathological diagnosis of thyroid carcinoma were enrolled in this study. Preoperative US examination and fine needle aspiration (FNA) biopsy results were evaluated. The tumor foci in thyroidectomy specimens that were not represented in preoperative US or FNA reports were classified as ITC. The tumor foci that match with the lesions defined in US or FNA results were classified as NITC.

RESULTS

Final histology revealed ITC in 326 patients (36%) and NITC in 580 patients (64% Mean age was 51.7 ± 11.11 in ITC group and 48.15 ± 13.1 in NITC group (P < .001). In NITC group 322 (55.5%) of the patients were operated for suspicious cytology while only 29 (8.9%) of the patients in the ITC group were operated because of this indication (P < .001). There were 1301 cancer foci in histopathology specimens. Among all these cancer foci, 434 (33.3%) were detected incidentally and 867 (66.7%) were detected non-incidentally. About 779 (89.9%) of nonincidental cancer foci were papillary cancer (PTC), while all of the incidental cancer foci were PTC. Mean size was 13 mm in NITC group and it was 3 mm in the ITC group and differed significantly between the groups (P < .001). Tumor size was ≤1 cm in 35.2% of the patients with NITC while 98.5% of patients with ITC had tumor ≤1 cm. The occurrence of multinodularity was higher in ITC than the NITC group (P < 001). Median TSH level was higher in patients with NITC than ITC while both were in the reference range (1.53 vs 1.03 μIU/mL, P < .001). The frequency of thyroiditis detected by US, and thyroid peroxidase antibody and thyroglobulin antibody positivities were similar in patients with ITC and NITC (P = .2, P = .86, and P = .26, respectively). The frequencies of capsular invasion (29.1% vs 7.9%), extrathyroidal extension (13% vs 4.2%), multifocality (35.8% vs 24.2%), non-complete resection (9.2% vs 1.8%), and lymph node metastasis (9.5% vs 1.8%) were significantly higher in the NITC group (P < .001, for each). Persistent/recurrent disease in patients with NITC was more frequent than patients with ITC (P = .004). This outcome was similar for cancers measuring ≤1 cm (P = .001).

CONCLUSION

ITC is often encountered in older patients and frequently determined in early stages with more favorable histopathological features and better prognosis.

Rare Occurrence of Incidental Finding of Noninvasive Follicular Thyroid Neoplasm With Papillary-Like Nuclear Features in Hürthle Cell Adenoma

INTRODUCTION

Hürthle cell adenoma is a rare benign lesion of the thyroid gland, however, controversies about its potential malignant behavior still remain. Among thyroid neoplasms, papillary carcinoma is the most common variant with great variety of histological subtypes demonstrating different biological behavior.

AIM

To raise the awareness of possible coexistence of these two lesions and discussion about possible therapeutic approaches.

CASE REPORT

A 42 year old female patient was examined because of the pain in the thyroid area. Cytological examination suggested Hürthle cell adenoma. Subsequently, right thyroid lobectomy was performed. Intraoperative frozen sections confirmed the diagnosis, yet final histological analysis revealed encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC), now reclassified as noninvasive follicular thyroid neoplasm with papillary- like nuclear features (NIFTP) within the adenoma, which was not noticed through scintigraphy, ultrasound, cytological and frozen section analysis.

CONCLUSIONS

Problems concerning both diagnostic and therapeutic approach to these lesions are being discussed, since opinions reported in the literature are divided, posing great challenge for the clinician in determining adequate therapeutic procedures.