CD56 Expression in Papillary Thyroid Carcinoma Is Highly Dependent on the Histologic Subtype: A Potential Diagnostic...

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• CD56 (NCAM) expression loss is a recognized diagnostic marker for papillary thyroid carcinoma (PTC).
• Aberrant CD56 expression can be observed in certain PTC variants, potentially complicating diagnosis.

Purpose of the Study:

• To quantitatively evaluate CD56 immunostaining H-scores in various thyroid tumors using digital image analysis.
• To determine the utility of CD56 expression levels in differentiating PTC from noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and its subtypes.

Main Methods:

• Digital image analysis was employed to assess CD56 immunostaining H-scores in 216 thyroid tumors.
• Statistical analysis (P-values) was used to compare CD56 H-scores across different thyroid tumor types and PTC variants.

Main Results:

• Papillary thyroid carcinoma (PTC) exhibited significantly lower CD56 H-scores compared to noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).
• CD56 expression was predominantly lost in classic PTC, infiltrative follicular variant, and diffuse sclerosing variant, while preserved in tall cell, Warthin-like, and cribriform-morular variants.
• Optimal H-score cutoffs of 180 and 30 were identified for distinguishing NIFTP from follicular adenoma and NIFTP from infiltrative follicular variant PTC, respectively.

Conclusions:

• CD56 expression is generally reduced in PTC, particularly in classic and infiltrative follicular variants, but preserved in NIFTP and other PTC subtypes.
• CD56 immunostaining is valuable for differentiating PTC from follicular-pattern thyroid neoplasms.
• Aberrant CD56 expression in uncommon PTC variants can pose a diagnostic challenge.