Table 2.
Definition of features used for the evaluation of benign and malignant processes
| Cytological feature | Definition | Grading scheme used |
|---|---|---|
| Pleomorphic parakeratosis10 | Pleomorphic, hyperchromatic nuclei of varying diameter in the stratum corneum | Present or absent |
| Mitotic figures11 – 13 | Condensed and separating chromosomes, typically arranged in a bipolar spindle | Quantity/five HPFs (mitotic index) |
| Abnormal mitotic figures12 – 15 | Mitotic figures were recognized as abnormal when they had tri/quadri/multipolar spindle instead of a bipolar spindle | Present or absent |
| Nuclear overlap (crowding)9,16,17 | Adjacent nuclei in contact or overlapping one another | Grading system 0–4 |
| Irregular nuclei9,17 | Deviations from round or oval shapes of nuclei (sharp angulations/clefts and curves in nuclear membrane), compared with cells in the uninvolved adjacent epidermis | Grading system 0–4 |
| Increased nuclear-cytoplasmic ratio5,9,18 | Ratio greater than 1 : 1 (i.e. when nucleus occupied more than half of the cell volume). (Normal nuclear-cytoplasmic ratio in squamous cells ranges 1 : 3–4 in different layers of the epidermis.) | Grading system 0–4 |
| Nuclear hyperchromasia2,9,13 | Increase in tinctorial properties of a nucleus or intensity of chromatin staining because of an increase in its chromatin content. To minimize the effect of staining, fixation and processing artifact, we evaluated this feature in lesional cells in comparison with uninvolved cells in the adjacent epidermis | Grading system 0–4 |
| Conspicuous nucleoli8,9 | Enlarged nucleoli easily visible at ×100 magnification or nucleoli that were approximately 2–3 μm or more in diameter were included in this category | Grading system 0–4 |
| Inconspicuous nucleoli8,9 | Small single delicate nucleoli visible only at higher magnifications (×200 or ×400) | Grading system 0–4 |
| Coarse chromatin2,9,12 | Multiple chromatin clumps, some of which may represent poorly formed nucleoli | Grading system 0–4 |
| Necrotic cells12 | Hypereosinophilic cells with pyknotic nuclei | Quantity/five HPFs (necrotic index) |
HPF, high-power field.