Application of Returned Cell Block Method (Cell Block from a Papanicolaou Staining Smear on a Glass Slide) for the Evaluation of Fine Needle Aspiration Cytology of Tumors of the Breast

BACKGROUND: In the fine needle aspiration cytology (FNAC) for tumors of the breast, evaluation is frequently difficult because of the thick‐layered cell clusters and blood inclusion. Such problems may be resolved by the returned cell block method, but its use has not spread worldwide. Here, we examined the application of the returned cell block method to cases involving difficulty in the evaluation of FNAC to diagnose tumors of the breast. METHODS: In Juntendo University Nerima Hospital, there were 22 cases which were difficult to diagnose by Papanicolaou stain only, and they underwent additional examination using the returned cell block method (cell block from a Papanicolaou staining smear on a glass slide). The usefulness of the returned cell block method in these cases was examined. RESULTS: Among the 22 cases, a correct diagnosis was facilitated in 20 cases using the returned cell block method. In 16 of the 20 cases, the difficulty in FNAC was because of thick‐layered cell clusters (12 cases) and blood inclusion (four cases). Among the 12 cases with difficulty because of the thick‐layered cell clusters, 10 cases (83%) comprised intraductal papilloma (six cases) and intraductal papillary carcinoma (four cases). Papilloma and papillary carcinoma were correctly diagnosed by the addition of histological images and immunostaining of myoepithelial cells using the returned cell block method. CONCLUSION: The application of the returned cell block method is useful for precise evaluation of the cytological diagnosis of tumors of the breast, especially papillary lesions. Diagn. Cytopathol. 2016;44:505–511. © 2016 The Authors Diagnostic Cytopathology Published by Wiley Periodicals, Inc.