How accurate can we diagnose breast lesion by fine needle aspiration cytology?

Fine needle aspiration cytology (FNA) is performed firstly in the diagnosis of breast lesion, as the FNA is less-invasive diagnostic procedure. Depending on the results obtained by the FNA, we subsequently perform core needle biopsy or Mammotome biopsy to determine the histological finding of the breast lesion. The purpose of the study is to evaluate the accuracy and limitation of diagnosis of breast lesion by FNA. The clinical data of 528 patients who underwent an operation for the breast lesion in the Shinshu University hospital from April 2004 to March 2009 were analyzed. Of 528 breast lesions, 488 were breast cancers, and 40 benign breast lesions. Of 528 breast lesions, 94 cases were excluded because CNB or MMT was performed firstly. In these cases, some were scheduled for the preoperative chemotherapy, and others were highly suspected to be ductal carcinoma in situ (DCIS), which was expected to be difficult to be diagnosed by FNA. Two hundreds and ninety two cases of 488 (59.8%) breast cancers and 21 of 40 (52.2%) benign lesions were diagnosed by FNA, respectively. Three of 299 cases (1%) determined to be 'malignant' by FNA were diagnosed as benign in the postoperative pathological diagnosis. 40 of 40 'suspicious for malignancy,' 40 of 46 'indeterminate,' 12 of 38 'normal or benign,' and 10 of 11 'inadequate' cases were finally diagnosed as cancer, in which scirrhous carcinoma, DCIS, small papillo-tubular carcinoma and lobular carcinoma were observed. It is speculated that enough specimens for diagnosis might not be obtained from these tumors by FNA, and that diagnosis by cytology itself might be difficult for these tumors. Although FNA is useful in the diagnosis of breast lesions, some lesions are very difficult to be diagnosed by FNA alone. We have to be careful in considering the conformity of the findings of image diagnoses with the cytological findings. Furthermore, when there is a lack of conformity between them, we should not to hesitate to perform CNB to obtain more histological information. (author)