[The "gray zone" in fine needle aspiration cytology of the breast]

Fine needle aspiration cytology (FNAC) is an essential procedure in the diagnosis of premalignant and malignant lesions of the breast. A "gray zone" exists between benign and malignant lesions in FNAC of breast; there an unequivocal diagnosis cannot be reached. Lesions in "gray zone" are categorized as "probably benign with atypia" (C3) and "probably malignant" (C4). Authors compared the cytology with histopathology and clinical follow-up of "gray zone" breast lesions, classified either as C3 or as C4 by FNAC. Amongst the total of 1679 FNACs, 85 (5%) were diagnosed as C3, whereas 101 (6%) were diagnosed as C4. Of the C3 cases, 48 patients underwent surgical biopsy. Histology proved malignancy in 21 (44%) cases, and was benign in 27 (56%) cases. Eighty-five open biopsies were performed out of the C4 cases. The histology was malignant in 76 (89%) cases, and benign in 9 (11%) cases. Lesions belong to "gray zone" should be taken into consideration in the FNAC of the breast and patients must be informed regarding this fact.