Cells are composed of two main parts, the nucleus and the cytoplasm. Both nuclear and cytoplasmic features can help in identifying cell type, but nuclear features are more useful in assessing if a cell is benign or malignant. Cytoplasmic features can help to identify the cell type.

There are some general principles for assessing whether cells are likely to be benign or malignant, although there are exceptions to these rules, depending on cell and sample type.