BACKGROUND: Fine-needle aspiration cytology (FNAC) of both palpable and non-palpable breast carcinomas has a high accuracy and sensitivity in dedicated centres. It is generally though that low-grade carcinomas have a distinctly lower sensitivity due to a discrete cellular atypia that might be difficult to appreciate. Grade 1 carcinomas make up about 45 % of screening detected breast carcinomas and about 20 % of symptomatic breast cancers. The aim of this study was to evaluate the diagnostic sensitivity of G1 carcinomas and identify the critical features in the cytological diagnostic work-up of these tumours.
MATERIAL AND METHODS: There were FNAC smears from 494 histologically confirmed grade 1 carcinomas diagnosed during 1996-2004. The cytological diagnoses were compared with the histology.
RESULTS: A definitive malignant diagnosis was given in 382 cases (77.3 %). 16.2 % were diagnosed as equivocal or suspicious, 4.8 % had been given a benign or probable benign diagnosis (false negatives). 13 cases (2.6 %) were unsatisfactory. The complete sensitivity was 92.7%. Invasive ductal carcinomas comprised 81.3 % of all cases. A definite malignant preoperative diagnosis was given in 80.8 % of these. Invasive lobular and tubular carcinomas comprised 7.1 % and 5.5 % of cases, respectively. They received a definitive, malignant preoperative diagnosis in 51.4 % and 55.6 %, respectively.
CONCLUSION: Preoperative FNAC diagnosis of grade 1 breast carcinoma has a high accuracy and sensitivity, especially in ductal carcinomas. Invasive lobular and tubular carcinomas receive a definite preoperative diagnosis in about 50 % of the cases. The main reason for not reaching a definitive malignant diagnosis was sampling error due to small tumours < 1 cm in diameter, irrespective of tumour subtype.
Key words: breast carcinoma, grading, fine needle aspiration, grade 1 carcinoma, pleomorphism, nuclear size, dissociation pattern.