Micronucleus study on breast cytology aspirate smears and its diagnostic utility

Abstract

Background:Micronucleus is a small fragment of nucleus present in the cells which have undergone chromosomal damage. It is used as a biomarker of genomic damage.Aims:We aim to study the presence of micronucleus on breast cytology smears and the use of scoring the micronucleus as an additional criteria for the classification of breast lesions with emphasis on borderline gray zone categories.Settings and Design:This is a cross-sectional retrospective descriptive study.Materials and Methods:Retrospective analysis of breast cytology smears received over a period of 2 years formed the basis of the study. Micronucleus scoring was done by counting the number of micronuclei in 1000 epithelial cells under oil immersion and compared in the benign, adenosis, usual/atypical ductal hyperplasia, and the three grades of infiltrating ductal carcinomas.Statistical Analysis:Descriptive analyses and one-way analysis of variance was used for statistical analysis.Results:Of the 243 cases, the average statistically significant (P < 0.05) micronuclei scores of the benign (190), adenosis (7), usual (11)/atypical (5) hyperplasia, grade 1, 2, and 3 carcinomas (30) were 0.5, 2, 2.9, 6.6, 13.2, 20.6, and 27.5, respectively (the corresponding median scores were 0.5, 2, 3, 6, and 20, respectively). Micronucleus score of ≤1 had a high sensitivity (100%) and specificity (99%) in confirmation of benign cases. Micronucleus score of ≥5 and <10 had a moderate sensitivity (60%) but a high specificity of 99% in detecting atypical ductal hyperplasia. Micronucleus score of ≥10 had a high sensitivity (96%) and specificity (99%) of detecting carcinomas.Conclusion:Micronucleus scores showed a gradual increase across the categories proving the gradual occurrence of genomic damage. Micronucleus scoring serves as an additional criterion for the diagnosis of breast lesions.

Study of micronuclei as a potent biomarker in breast cytology aspirates

“…An Unpaired t test (with Welch's correction) showed significant difference in Micronuclei score between malignant and benign breast lesions (P = 0.0046, df = 7.018). Similar findings were observed Sylvia MT et al 13 Hemalatha et al 16 in their study reported a significant difference in occurrence of micronuclei between benign and malignant cases as well as between various grades of malignancy. There was overlapping of values between few fibroadenoma cases and infiltrating ductal carcinoma and a score of less than 5 for 1000 cells was seen in most cases of fibroadenoma, and a higher score of more than 5 per 1000 cells was seen in infiltrating ductal carcinoma.…”

“…In our study, we observed 02 cases were grade 1 with average micronucleus score /1000 epithelial cells of 8, 02 cases were grade 2 and the average micronucleus score was 18.5 and 02 cases were grade 3 with average micronucleus score of 27.5. In Sylvia MT et al study 13 10 cases (33.3%) were grade one, 14 cases (46.6%) were grade two, and 6 cases (20%) were grade three tumors, and the average micronucleus score of these groups were 13.2 ± 5.7, 20.36 ± 8.5, and 27.5 ± 4.18, respectively.…”

“…In the present study, the mean micronucleus score of the benign cases was 1.42 ± 0.85 (Range 0-4). In a study conducted by Sylvia MT et al 13 the mean micronucleus score of the benign cases was 0.5 ± 0.52 (Range 0-1).…”

“…The peak incidence of benign tumors was in the third decade of life while malignancy was more frequent in the fifth decade. In Sylvia MT et al study 13 the average age group of women with fibroadenoma was 25 years and phyllodes was 60 years. The mean age of this group was 25 years.In Mangam SN et al study 15 the mean ages (± standard deviation) of the fibroadenoma and IDC groups were 28.74 ± 8.44 and 49.84 ± 12.62 years, respectively.…”

“…Out of these 60 cases, 38 cases were reported as fibroadenoma, 10 cases as adenosis, 04 cases as usual ductal hyperplasia, 02 cases as atypical ductal hyperplasia, 6 cases of infiltrating ductal carcinomas. In a study conducted by Sylvia MT et al 13 there were 190 cases of benign tumours (fibroadenoma/phyllodes); 90 cases of benign proliferative breast disease, 30 cases of cystic diseases (fibrocystic disease, abscess, simple cysts), 7 cases of adenosis, 11 cases of usual ductal hyperplasia, 5 cases of atypical ductal hyperplasia and 30 cases of infiltrating ductal carcinomas. Basher ES et al 14 examined (74) benign breast tumors and (26) malignant tumors (Infiltrating ductal carcinoma, not otherwise specified).…”