Touch imprint and crash preparation intra operative cytology versus frozen section in thyroid nodule

Intra operative cytology (IC), including touch imprint (TI) and crash preparations (CP), in general has been demonstrated to be a diagnostic tool for many organs but its validity and reliability for diagnosis of thyroid nodules remain controversial. We evaluate the diagnostic value of frozen section, touch imprint, crash preparation and the combination of touch imprint and crash preparation and the combination of frozen section, touch imprint and crash preparation.

[corrected] 55 intra operative specimens from patients with thyroid nodules who underwent thyroidectomy were evaluated at Alzahra and vali-Asr hospital laboratories. For all of the patients frozen section (FS), touch imprint (TI) and crash preparation (CP) was obtained and reviewed by two pathologists at the same time. Serial TI and CP, and FS, TI and CP were reviewed by the same pathologists. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and accuracy were calculated according to the permanent section as the gold standard test.

In our study sensitivity, specificity and accuracy for FS was 100%, 97.6% and 98.1% respectively; for TI they were 78.6%, 95% and 92.4%; for CP they were 78.6%, 92.7% and 89.9%; for serial TI and CP they were 85.7%, 92.7% and 90.9%; and for the combination of FS and TI and CP they were 100%, 97.6% and 98.18% respectively.

Intra operative cytology (including TI and CP) seems to be a useful, valuable and inexpensive method in clinics, which do not have equipment for frozen sections. Intra operative cytology combined with FS increased the overall accuracy of diagnosis. Further studies are needed to validate the obtained results of this study.