Combined Core Needle Biopsy and Fine Needle Aspiration Cytology UsingReturned Cell Block Method is Effective for Diagnosis of Cystic Lesions ofthe Breast

Background: Core needle biopsy (CNB) and fine needle aspiration cytology (FNAC) are useful methods to diagnose cystic lesions of the breast. The first English article describing the returned cell block method (RCBM: cell block from a Papanicolaou staining smear on a glass slide) was reported by us, and we also reported the usefulness of RCBM for the FNAC-based evaluation of tumors of the breast. In the present study, diagnostic procedures of CNB and FNAC using RCBM for cystic lesions of the breast were studied. Methods: Forty-seven patients with cystic lesions of the breast diagnosed by sonographic examination and sonographically-guided FNAC were evaluated. In all cases, the evaluation of FNAC was performed by Papanicolaou staining smears, and RCBM was added in cases that were difficult to evaluate. The data from CNB (26 cases) and surgery (15 cases) were also evaluated. Results: The accuracy of diagnosing carcinoma of FNAC from Papanicolaou staining smear was 56.2%. The diagnostic accuracy increased to 75% on using RCBM, and the same level of accuracy was found on CNB. In 4 cases, a diagnosis of carcinoma was made by CNB only (2 cases) or FNAC using RCBM only (2 cases). Subsequently, the accuracy increased to 87.5% due to the combination of CNB and FNAC using RCBM. Conclusions: Combined CNB and FNAC using RCBM is effective for the diagnosis of cystic lesions of the breast. Based on this new finding, we propose a procedure to diagnose cystic lesions of the breast by CNB and FNAC using RCBM.