Role of fine-needle aspiration biopsy in breast lesions: analysis of a series of 4,110 cases.

From January of 1990 to December of 1992, 6,954 consecutive cytologic breast fine-needle aspiration biopsies (FNAB) were performed at the Laboratory of Pathology of Sant'Anna Hospital in Turin. Of these cases 62% were solid nodes, 35% were cystic nodes, and 2.7% were nonpalpable breast lesions (stereotaxic or ultrasound guided FNAB). We verified 4,110 cases: 913 cases underwent surgery and 3,197 were evaluated clinically, and/or cytologically, and/or with mammography at least 1 yr after the first diagnosis, or checked with the database of the Tumor Registry of Turin. In our series the FNAB sensitivity was 94.6%, specificity was 99.9%, accuracy was 98.8%, inadequate samples were 6.4%, false-negative rate was 1.4%, and false-positive rate was 0.3%. Our results indicate that the use of cell block improves sensitivity (from 85.2 to 94.6%) and strongly reduces false-negative results (from 3.9 to 1.4%). We conclude that FNAB is a discriminant procedure to the surgical biopsy in cases with clinical, ultrasound, or mammographic low or intermediate suspect, contributing to allow a high malignant/benign surgical biopsy rate and to reduce the need for frozen section diagnosis and medical costs.