Stratified diagnostic approach to fine needle aspiration of the breast.

The clinical value of fine needle aspiration (FNA) of the breast is enhanced by incorporating into the cytologic diagnosis explicit comments on the level of diagnostic certainty. This stratification of diagnostic certainty is based predominantly on the cytologic features but occasionally also takes into consideration the clinical situation. Strong clinical and mammographic suspicion of mammary carcinoma associated with FNA, diagnostic of typical, intermediate to high-grade mammary carcinoma, warrants proceeding to definitive therapy without further diagnostic studies. False-positive results are virtually eliminated by placing cases with any uncertainty into a "probable" category, which does not support definitive therapy. In addition, oversimplified "benign versus malignant" approaches to FNA diagnoses ignore the heterogeneity of breast masses, with in situ and low-grade carcinomas warranting special clinical management and usually being placed in the "probable" category. Thus, malignant diagnoses are stratified into "definite" and "probable," with only the former supporting definitive therapy. Within our recent series of 1,005 FNAs of the breast, we were able to confirm the diagnosis in all 62 patients with a "definite" carcinoma diagnosis, and only 3 of 25 "probable" cancer diagnoses were benign at tissue biopsy. Thus, false-positive results were successfully avoided in the "definite" category. Furthermore, a much greater incidence of unusual and good prognosis tumor types were identified by the "probable" category. If the clinical setting is relatively suspicious only, a definitive diagnosis of cancer by FNA is rare and not necessary because the clinical question to be addressed is only whether to biopsy. This approach to FNA diagnosis, unlike the oversimplified "benign versus malignant" scheme, provides an approach that is more likely to result in optimal therapy for breast neoplasms, with low-grade or in situ carcinomas requiring special clinical management since these types of cancers are found predominantly in the "probably malignant" category. It also provides additional security against false-positive diagnoses by incorporating clinical level of certainty statements into FNA diagnostic categories, which more closely reflect the diversity and inherent complexity in the appropriate diagnosis and therapy of mammary carcinomas.