Comparison of Cytoscrape Cell Blocks With Conventional Cytology Smears in the Diagnosis of Suspicious and Malignant Breast Lesions at Kenyatta National Hospital

Abstract

Background: Histological examination of formalin fixed tissue sections is the gold standard for diagnosis in pathology laboratories. Cell blocks, however, can be prepared when surgical biopsy is not available or contraindicated. This study investigated the cytoscrape cell block (CSB), a valuable yet not popular technique in routine clinical practice. The technique utilizes conventional smears as fixed and stained on the slide for an improved architectural picture and sections for ancillary studies. Study design: Analytical cross-sectional study. Study setting: Kenyatta National Hospital (KNH), histology and cytology laboratories. Methodology: 55 smears of breast lesions reported as suspicious of malignancy or malignant at KNH between January, 2017 and December, 2020 were obtained and included in the study. The smears were de-coverslipped, destained and scraped directly into filter papers for cell block preparation. Thin sections were prepared for Hematoxylin and Eosin (H&E) staining and immunocytochemistry using specific monoclonal antibodies to determine expression of Estrogen Receptor (ER), and Human Epidermal growth factor Receptor 2 (HER-2). Agreement between techniques was determined using Cohen’s kappa statistic and sensitivity analysis performed against the gold standard (histology). Ethical approval was obtained from UON/KNH Ethics and Research Committee (Approval no. P679/10/2023). Results: The agreement between CSB and conventional smears was 72.3% (0.43 kappa value). CSB showed an agreement of 85% with histology against conventional smears’ 75% (0.69 kappa value). On sensitivity analysis, CSB had 83% accuracy (sensitivity of 100%, specificity of 66.7%, with PPV of 78.6% and NPV of 100%). Immunohistochemistry was performed in 47 cases out of 55 with sufficient diagnostic material. The findings showed that 38% (n =18) were immunoreactive. Among those with negative findings 62% (n =29), five of the cases did not have diagnostic cells and 24 were negative for both Her-2 and ER markers. Conclusion: CSB offers significant advantages over conventional cytology in detecting breast cancer, therefore a combination of the techniques is useful in breast cancer diagnosis when surgical biopsies are not available. Diagnostic laboratories should therefore adopt CSB technique given its higher accuracy to enhance diagnostic precision and patient outcome