Utility of morphological markers of chromosomal instability in breast cytology- A study of 100 cases.

Aim: Carcinogenesis is associated with multiple mutations that lead to chromosomal instability (CIN). Our aim was to study the role of markers of CIN on breast cytology and correlate with histopathological diagnosis.

Materials and methods: A retrospective observational study was conducted over a year on 100 breast cytology cases. Leishman-stained smears were examined for the number of micronuclei (MN), chromatin bridge (CB), and multipolar mitosis (MPM). MNs were counted manually in 1,000 cells under oil immersion (1000×). The frequency of CB and MPM was also noted. The malignant cases were graded as low (grades 1 and 2) and high (grade 3).

Results: The mean age of the patients was 43.47 ± 15.81 years. The mean MN score for fibroadenoma cases was 4.54 (±1.5) and for malignant cases was 29.32 (±8.15). The receiver-operator curve (ROC) curve analysis confirmed >9 MN score as 100% specific and 100% sensitive for malignancy (area under the curve [AUC] =1). A significant comparison was noted between the mean MN of benign and malignant cases (P < 0.000001). The mean MN score for low-grade cases was 26.64 (±5.85) and for high-grade cases was 33.68 (±5.85) with a significant difference observed on comparing the population mean MN with a grade of malignancy (P-value = 0.01886). The difference between the frequencies of CB in low and high-grade cases was also found to be significant (P-value = 0.04135).

Conclusion: The presence and scoring of markers of CIN (MN, CB, and MPM) on breast cytology have potential significance in the diagnosis of breast lesions.