Follicular variant of papillary thyroid carcinoma: cytological indicators of diagnostic value

Understanding and Overcoming the Pitfalls in Cytopathological Diagnosis of Hyalinizing Trabecular Tumor of Thyroid

Hyalinizing trabecular tumor (HTT), a rare low-malignant-potential thyroid neoplasm, is usually treated with conservative surgery. However, cytomorphological diagnosis of HTT is challenging due to the significant overlap of nuclear features with more common malignancies such as papillary thyroid carcinoma (PTC), which usually requires more radical surgical intervention. To avoid unnecessary overtreatment, a precise diagnosis of HTT is therefore essential. Advances in molecular diagnostics provide the opportunity to overcome the limitations of cytological analysis. We present a case of HTT in a 71-year-old male who was initially suspected to be PTC based on cytopathology. However, further molecular analysis revealed PAX8::GLIS3 gene fusion, classifying the lesion as HTT and preventing surgical overtreatment. We discuss the diagnostic pitfall of cytopathology in HTT and suggest using emerging molecular genetic tools to avoid it.

The Role of Claudin-1 Expression in Follicular and Papillary Thyroid Neoplasm

OBJECTIVE

This study evaluated differences in Claudin-1 expression between follicular adenoma (FA), follicular thyroid carcinoma (FTC), follicular variant papillary thyroid carcinoma (FV-PTC), and papillary thyroid carcinoma (PTC).

MATERIAL AND METHODS

This study used a cross-sectional approach. Immunostaining using the polyclonal antibody Claudin-1 was performed on 75 samples divided into 20 samples for follicular adenoma, follicular thyroid carcinoma, papillary carcinoma, and 15 samples of follicular variant thyroid carcinoma, respectively.

RESULTS

Claudin-1 expression is detected on the cytoplasmic membrane of tumor cells and appears to be varied among thyroid neoplasms. The claudin-1 expression score revealed a statistically significant difference between FA against FV-PTC, FA versus (vs) PTC, and FTC vs PTC, with median values of 4 vs 6 (p = 0.016), 4 vs 8 (p = 0.001), and 5 vs 8 (p = 0.002), respectively. However, there was no statistically significant difference in scores between the FA and the FTC (4 vs 5), or between the FTC and the FV-PTC groups (5 vs 6 (p=1,000).

CONCLUSION

These results suggest that Claudin-1 may be capable of discriminating follicular adenoma from classic and follicular variant of papillary thyroid carcinoma. It can also differentiate follicular thyroid carcinoma and papillary thyroid carcinoma, especially for cases challenging to assess by hematoxylin and eosin staining. It still holds promise in providing targeted cancer therapy.

Diagnostic Efficacy of Ultrasound-Guided Fine Needle Aspiration Combined with the Bethesda System of Reporting

Background:

Image-guided fine needle aspiration cytology (FNAC) is emerging as an important diagnostic tool in the evaluation of thyroid swellings.

Aim:

This study aims to assess the efficacy of ultrasound (US)-guided FNAC combined with “The Bethesda system' of reporting as a primary screening test for all thyroid lesions.

Settings and Design:

A prospective cohort study was made and all the US-guided FNACs done were followed up to find out the histopathological diagnoses wherever surgery was done.

Materials and Methods:

In all, 1050 patients who underwent US-guided FNAC were studied during a period of 1 year. Age, sex, cytological features, and histological diagnoses were analyzed. Statistical analyses of all the findings were done to derive conclusions.

Results:

Of the 1050 patients, only 10.5% underwent surgery. Higher than expected rate (as per the Bethesda system) of malignancy was noted with the so-called grey zone lesions. The test results revealed a high level of sensitivity, specificity, and diagnostic accuracy.

Conclusion:

The study showed that The Bethesda System of Reporting Thyroid Cytology provides effective communication between clinician and pathologists thereby enabling clear management strategies. We also concluded that US-guided FNACs offer better results compared with palpation-guided FNACs.

PTEN loss is associated with follicular variant of Middle Eastern papillary thyroid carcinoma

Background:

PTEN gene at chromosomes 10q23.3 is a tumour suppressor gene that is inactivated in many types of human cancers. The known mechanisms of PTEN inactivation are rendered to mutation, epigenetic silencing by aberrant methylation or gene deletion. Although PTEN role has been documented in many cancers, PTEN alteration in papillary thyroid carcinoma (PTC) has not been fully elucidated. The aim of this study is to comprehensively investigate PTEN alterations in a large cohort of Middle Eastern papillary thyroid cancer by immunohistochemistry and fluorescent in situ hybridisation (FISH).

Methods:

PTEN protein expression was analysed by immunohistochemistry in a tissue microarray (TMA) format in a large cohort of more than 1000 patients with papillary thyroid cancer. Copy number changes in PTEN were analysed by FISH and data were correlated with clinicopathological parameters along with survival analysis.

Results:

PTEN inactivation reflected by complete absence of staining was seen in 24.5% of PTC samples, whereas PTEN deletion was seen only in 4.8% of the tested samples by FISH. No association was seen between PTEN loss of protein expression and PTEN gene deletion. However, interestingly, PTEN loss of expression was significantly associated with the follicular variant subset of papillary thyroid cancer.

Conclusion:

Our study confirmed that PTEN might have a role in pathogenesis in a subset of PTC. PTEN loss of protein expression is a more common event in follicular variant of papillary thyroid cancer. Lack of association between PTEN loss of protein expression and PTEN gene deletion might indicate that gene deletion may not be the sole cause for PTEN loss of expression and these results might raise the possibility of other mechanism such as promoter methylation-mediated gene silencing to be responsible for PTEN inactivation.