Challenge in the Pathological Diagnosis of the Follicular- Patterned Thyroid Lesions

Abstract

Background: The follicular-patterned thyroid lesions (FPTLs) include hyperplastic nodules (HN), follicular adenoma (FA), non-invasive follicular neoplasm with papillary-like nuclear features (NIFTP), follicular carcinoma (FC), and the follicular variant of papillary carcinoma (FVPTC). Sometimes the pathologists cannot accurately separate these lesions from each others on a histological basis. Aims: To evaluate the utility of immunohistochemistry in the diagnosis of FPTLs. Materials and methods: Immunohistochemical analysis, incorporating 83 cases of histologically confirmed FPTLs out of which 20 carcinomas, 51 benign FPTLs (38 HN and 13 FA), and 12NIFTP were separated from each others using four immunostains (HBME-1, CK19, Galectin-3, and CD56). Results: We found statistically significantly more frequent expression of HBME-1, CK19, Galectin-3 proteins in carcinomas as compared to benign FPTLs (p = <0.01). HBME-1 and Galectin-3 were the most sensitive markers for the diagnosis of malignant FPTLs (75%). Galectin-3 was the most specific marker for the diagnosis of carcinoma (90.3%). Conclusions: The histomorphological features remain the cornerstone of the diagnosis of FPTN. Although HBME-1, Galectin-3, and CK19 immunostains have some diagnostic value in the separation of malignant from benign FPTLs, they are variably expressed in the benign and malignant FPTLs. No single immunostain has sufficient sensitivity and specificity and therefore their diagnostic use is controversial. Future studies are mandated to find more reliable markers that can separate between benign and malignant FPTLs.

2023 European Thyroid Association Clinical Practice Guidelines for thyroid nodule management

“…The morphology remains the cornerstone to distinguish benign from malignant nodules ( 77 ). HBME-1, Galectin-3, and CK19 immunostaining are more frequently positive in thyroid carcinomas, but their expressions are variable, and no single stain has sufficient sensitivity and specificity to be recommended for routine practice ( 78 ).…”

Immunohistochemical Profile of Parathyroid Tumours: A Comprehensive Review

“…From the point of view of surgical pathologist, it is important to remember that thyroid tumours and cancer metastases in cervical lymph nodes also are likely to express cytokeratin 19 [111][112][113][114][115]. Hence, the diagnostic value of cytokeratin 19 in parathyroid pathology is low but this antigen could rather evoke scientific interest because of its up-regulation in carcinoma.…”

Proteomics profile in encapsulated follicular patterned thyroid neoplasms

“…The latest version of the 5th World Health Organization's Classification of Endocrine and Neuroendocrine Tumors has redefined thyroid cancers, providing insights into their biology, histogenesis, and molecular profiles 3 , 4 . Certain thyroid follicular lesions present diagnostic challenges due to morphological and architectural similarities, leading to interobserver variations among practitioners in the field of thyroid pathology 5 . Encapsulated follicular-patterned tumors share predominant follicular patterns (over 95%) and are surrounded by thin or thick fibrous capsules 4 , 6 , 7 .…”