Constitutive Cytomorphologic Features of Medullary Thyroid Carcinoma Using Different Staining Methods

• Main Authors: Chih-Yi Liu, Chien-Chin Chen, Andrey Bychkov, Shipra Agarwal, Yun Zhu, Jen-Fan Hang, Chiung-Ru Lai, Hee Young Na, So Yeon Park, Weiwei Li, Zhiyan Liu, Deepali Jain, Ayana Suzuki, Mitsuyoshi Hirokawa, Noel Chia, Min En Nga, Tikamporn Jitpasutham, Somboon Keelawat, Shinya Satoh, Dilini Gunawardena, Priyanthi Kumarasinghe, Chan Kwon Jung, Kennichi Kakudo
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: Diagnostics
• Subjects: cytology; fine-needle aspiration; medullary thyroid carcinoma; sensitivity; specificity; thyroid
• Online Access: https://www.mdpi.com/2075-4418/11/8/1396

(1) Background: Accurate preoperative identification of medullary thyroid carcinoma (MTC) is challenging due to a spectrum of cytomorphologic features. However, there is a scarcity of studies describing the cytomorphologic features as seen on fine-needle aspiration (FNA) smears prepared using different staining methods. (2) Methods: We performed a retrospective study on MTC cases with available FNA slides from 13 hospitals distributed across 8 Asia-Pacific countries. The differences in the constitutive cytomorphologic features of MTC with each cytopreparatory method were recorded. A comparative analysis of cytologic characteristics was carried out with appropriate statistical tests. (3) Results: Of a total of 167 MTC samples retrospectively recruited, 148 (88.6%) were interpreted as MTC/suspicious for MTC (S-MTC). The staining methods used were Papanicolaou, hematoxylin-eosin, and Romanowsky stains. Seven out of the eleven cytologic criteria can be readily recognized by all three cytopreparatory methods: high cellularity, cellular pleomorphism, plasmacytoid cells, round cells, dyshesive cells, salt-and-pepper chromatin, and binucleation or multinucleation. An accurate diagnosis was achieved in 125 (84.5%) of the 148 samples whose FNAs exhibited five or more atypical features. Conclusions: The present work is the first study on MTC to compare the morphological differences among the cytologic staining techniques. We investigated the constitutive features and the reliability of diagnostic parameters. A feasible scoring system based upon cytomorphologic data alone is proposed to achieve a high degree of diagnostic accuracy.