Young investigator challenge: The accuracy of the nuclear-to-cytoplasmic ratio estimation among trained morphologists

The estimation of the nuclear-to-cytoplasmic ratio (N:C ratio) is an important factor in diagnosing atypia and malignancy in pathological specimens, particularly in cytology. Many algorithms for determining malignant potential make reference to specific, decimal N:C ratios without specifying how the ratio should be measured, with the implication that the observer is intended to estimate this ratio by eye. The authors wanted to determine how accurate trained morphologists (including attending pathologists, pathology residents, and cytotechnologists) are at estimating the N:C ratio without a measuring device.

Two surveys were prepared containing ideal and real cell images of various N:C ratios. Participants were instructed to select their best estimate from a list of decimal ratios. The data were tabulated and analyzed to determine how accurate the estimates were and whether there was any performance difference between ideal and real images.

The absolute and percentage deviation from the actual N:C ratio decreased steadily with increasing N:C ratio. Aggregate performance was found to be closely correlated between real and ideal images, although interobserver variation was not significantly different among participants in the real images quiz, but was significantly different on the ideal images quiz.

Trained morphologists make relatively accurate estimations of the N:C ratio and become increasingly more accurate as the depicted N:C ratio increases. This suggests that including N:C ratio decimals as a criteria for the diagnosis of atypia is valid for high N:C ratios.