Hashimoto's thyroiditis shares features with early papillary thyroid carcinoma

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Neoplastic transformation is a spectrum from normal to malignant states.
• Conventional histology with nuclear features is the gold standard for papillary thyroid carcinoma (PTC) diagnosis.
• Immunohistochemistry and molecular profiling are increasingly used for neoplasm diagnosis.

Purpose of the Study:

• To investigate the diagnostic overlap between papillary thyroid carcinoma and Hashimoto's thyroiditis.
• To highlight the significance of the RET/PTC gene rearrangement in PTC diagnosis.
• To explore the presence of submicroscopic PTC foci in Hashimoto's thyroiditis.

Main Methods:

• Histopathological examination focusing on nuclear features.
• Immunohistochemical staining.
• Molecular profiling, specifically analyzing RET/PTC gene rearrangement.

Main Results:

• The RET/PTC gene rearrangement is highly specific for papillary thyroid carcinoma.
• Significant overlap exists in morphology, immunohistochemistry, and molecular profiles between PTC and Hashimoto's thyroiditis.
• Hashimoto's thyroiditis frequently harbors RET/PTC rearrangements, indicating submicroscopic PTC foci.

Conclusions:

• Submicroscopic foci of papillary thyroid carcinoma are consistently present in Hashimoto's thyroiditis.
• The RET/PTC gene rearrangement is a key molecular marker for PTC, also found in Hashimoto's thyroiditis.
• Further research is needed to predict the progression of these microscopic foci to overt papillary thyroid carcinoma.