C4 (Suspicious of malignancy)
This category encompasses the aspirates with highly atypical features, almost certainly coming from a malignant lesion although a confident diagnosis cannot be made.
- The specimen is scanty, poorly preserved or poorly prepared, but some cells with features of malignancy are present.
- The sample may show some malignant features in the absence of overtly malignant cells. The degree of abnormality should be more severe than in the previous category.
- The sample has an overall benign pattern with large numbers of naked nuclei and/or cohesive sheets of cells but with occasional cells showing distinct malignant features.
(Modified from: GUIDELINES FOR NON-OPERATIVE DIAGNOSTIC PROCEDURES AND REPORTING IN BREAST CANCER SCREENING. NHSBSP Publication No 50 June 2001).