Constitutive Cytomorphologic Features of Medullary Thyroid Carcinoma Using Different Staining Methods

Area of Science:

• Cytopathology
• Oncology
• Surgical Pathology

Background:

• Medullary thyroid carcinoma (MTC) diagnosis preoperatively is challenging due to varied cytomorphologic features.
• Limited research exists on MTC cytomorphology in fine-needle aspiration (FNA) smears using different staining methods.

Purpose of the Study:

• To compare cytomorphologic features of MTC across various staining techniques.
• To identify reliable diagnostic parameters for MTC on FNA smears.
• To propose a scoring system for improved diagnostic accuracy.

Main Methods:

• Retrospective analysis of MTC FNA slides from 13 hospitals in 8 Asia-Pacific countries.
• Evaluation of cytomorphologic features using Papanicolaou, hematoxylin-eosin, and Romanowsky stains.
• Comparative analysis of cytologic characteristics with statistical testing.

Main Results:

• Out of 167 MTC samples, 148 (88.6%) were MTC or suspicious for MTC.
• Seven key cytologic criteria (high cellularity, pleomorphism, plasmacytoid cells, round cells, dyshesion, salt-and-pepper chromatin, binucleation/multinucleation) were consistently recognized across all three stains.
• Accurate diagnosis was achieved in 125 (84.5%) of cases with five or more atypical features.

Conclusions:

• This study is the first to compare MTC morphological differences across cytologic staining techniques.
• Constitutive features and diagnostic parameter reliability were investigated.
• A scoring system based on cytomorphologic data alone is proposed for high diagnostic accuracy.