“…That is, we identified cases in which the mass had been classified into Category B on the basis of EUS-FNAC but into Category C/D on the basis of EUS-FNAB and vice versa. We then evaluated cytologic features as: background (clear vs. necrotic background) ('clear background' was defined as viable cells with an absence of necrotic tissue; 'necrotic background' was defined as diffuse necrosis complicated with various numbers of conspicuous malignant cells); 15,16 quantity of atypical cells in the sample (few vs. numerous); characteristics of the nuclei, that is, arrangement (regular vs. irregular), atypia (mild, severe (with severe nuclear atypia manifested as anisonucleosis or irregularly shaped nuclei, or uneven distribution of coarse chromatin)); and the nuclear/cytoplasmic (N/C) ratio (<60%, ≥60%). Further, we examined the following histomorphologic features of these masses: background (clear, necrotic), quantity of atypical cells in the sample (few, numerous), atypical glandular structures (few <3, numerous ≥3) cytologic atypia (mild, severe), and atypical cells that appear degenerate or necrotic (few, numerous).…”