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.

1. The specimen is scanty, poorly preserved or poorly prepared, but some cells with features of malignancy are present.
2. 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.
3. 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).