Researchers have developed a simple scoring system that can be used to preoperatively identify patients who are at high risk of developing medullary thyroid carcinoma (MTC), according to a study published in Diagnostics.

They achieved this by first evaluating the constitutive cytomorphologic features of MTC using various staining methods and then combining the diagnostic parameters identified. This approach achieves a desirable accuracy when 6 or more atypical features are present. 

The first-line method for diagnosing MTC is fine-needle aspiration (FNA) with an ultrasound scan. However, the diverse appearance of MTC on aspiration cytology presents a challenge to reaching an accurate diagnosis. A lack of research into the different cytomorphologic features as seen on FNA using various staining methods confounds the problem.


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The exact reporting of indeterminate FNA samples can affect the extent of surgery performed. The purpose of this study is to assess the merits of each staining method in an effort to improve diagnostic performance. 

Read more about MTC etiology

Researchers conducted a retrospective study on 167 confirmed MTC cases with the participation of 23 cytopathologists from 13 hospitals across 8 Asia-Pacific countries. The differences in the constitutive cytomorphologic features of MTC with the different staining methods (Papanicolaou, hematoxylin-eosin, and Romanowsky) were identified. Researchers then carried out a comparative statistical analysis of the cytologic characteristics observed. 

From the 167 MTC samples, a total of 148 (88.6%) were interpreted as MTC or suspicious for MTC. Seven cytological criteria could be identified from all 3 staining methods (>50% frequency): 

  • High cellularity
  • Dyshesive cells
  • Plasmacytoid cells
  • Cellular pleomorphism
  • Salt-and-pepper chromatin
  • Round cells
  • Binucleation or multinucleation

Of the 148 samples whose FNAs exhibited 5 or more atypical features, an accurate diagnosis was made in 125 of them (84.5%). According to the Youden index, the optimal cutoff was equal to or larger than 6, with a specificity of 68.4% (95% CI, 43.4%-87.4%) and a sensitivity of 66.2% (95% CI, 58%-73.8%).

Reference

Liu C-Y, Chen C-C, Bychkov A, et al. Constitutive cytomorphologic features of medullary thyroid carcinoma using different staining methods. Diagnostics. Published online August 2, 2021. doi:10.3390/diagnostics11081396