title: An audit of "equivocal" (C3) and "suspicious" (C4) categories in fine needle aspiration cytology of the breast.
abstract: We have audited the frequency of use and outcome of the "equivocal/atypia probably benign" (C3) and "suspicious of malignancy" (C4) category for breast cytology in our Unit. A total of 14 935 cytological specimens were reported by at least one of the three pathologists with a special interest in breast pathology, according to five categories of the NHSBSP guidelines for cytology reporting, 1992; 3.7% (555 cases) and 3.9% (587 cases) of cases were classified as equivocal (C3) and suspicious (C4), respectively, giving a total rate (C3 + C4) of 7.6%. Of the C3 cases, 68% were subsequently benign and 32% were malignant. Of the C4 cases, 19% were subsequently benign and 81% malignant. The commonest benign lesions in both categories were fibroadenomas (7.6% of C3 and 19.8% of C4), fibrocystic change (14.3% of C3 and 12.5% of C4), radial scars (6.2% of C3 and 10.4% of C4) and papillomas (6.2% of C3 and 6.3% of C4). Of the malignant lesions (particularly those classified as C3), a high proportion were low grade or special type cancers. The categories of atypia probably benign (C3) and suspicious of malignancy (C4) in breast cytology provide a strategy for classification of problematic or uncertain cases; this maintains the predictive value of the benign (C2) and malignant (C5) categories, and allows separation of these difficult cases into clinically useful groups with differing probabilities of malignancy.
authors.affiliation: Department of Histopathology, Nottingham City Hospital NHS Trust, Hucknall Road, Nottingham NG5 1PB, UK.
authors.forename: R A
authors.initials: RA
authors.lastname: Deb
authors.forename: P
authors.initials: P
authors.lastname: Matthews
authors.forename: C W
authors.initials: CW
authors.lastname: Elston
authors.forename: I O
authors.initials: IO
authors.lastname: Ellis
authors.forename: S E
authors.initials: SE
authors.lastname: Pinder
mesh_terms: D001707:Biopsy, Needle; D001940:Breast / Q000473:pathology*; D001941:Breast Diseases / Q000145:classification / Q000175:diagnosis*; D001943:Breast Neoplasms / Q000145:classification / Q000175:diagnosis*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008485:Medical Audit; D011237:Predictive Value of Tests