In suspicious for malignancy thyroid nodule aspirates, nuclei characteristics deserves special attention in reported cytology analysis - real world scenario cohort.

Objective: To identify cytologic characteristics in a suspicious for malignancy cohort that may help to recognize false positives in cytopathological tests of thyroid nodules in a "real world scenario", with histopathological reports as the gold standard.

Methods: Cytomorphologic features of suspicious for malignancy thyroid nodules in a 13-year retrospective database were reviewed. Therefore, we identified false positive cases, analyzed the possible causes of cytopathological diagnostic failure and calculated the frequency of false positive results and the risk of malignancy in the suspicious for malignancy cohort.

Results: Among the 289 suspicious for malignancy type nodules, 283 were malignant, 5 were benign, and 1 was a noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). The most frequently reported cytology features were nuclear grooves and pseudoinclusions; however, they were present in malignant and benign specimens. Statistical analysis revealed that the presence of micronucleoli (p < 0.001) and/or irregular/oval nuclei (p = 0.05) were the characteristics most strongly associated with malignancy. The risk of malignancy was 98% in this study.

Conclusion: The presence of micronucleoli and nuclear irregularity was highly predictive of malignancy according to suspicious for malignancy cytology and were not present in false positive patients. Hence, careful examination of nuclear characteristics can be helpful for identifying true malignancies via suspicious for malignancy cytology. This was significant even when only a qualitative analysis was taken into account.