Stereological estimation of mean nuclear volume as a prognostic factor in canine subcutaneous mast cell tumors

Classification schemes regarding canine subcutaneous mast cell tumors (csMCTs) remain elusive, lack consensus, and are prone to interobserver variability and bias. This observational study aimed to assess the reproducibility and the prognostic significance of volume-weighted mean nuclear volume ((Formula presented.)), a stereological estimation offering insights into nuclear size and its variability, in csMCTs. Thirty csMCTs were selected with information regarding outcome, and (Formula presented.) was estimated using the “point-sampled intercept” method. Interobserver and intraobserver (Formula presented.) reproducibility yielded concordance coefficients near or above 0.90. Regarding previously reported risk factors (pattern, mitotic count, and multinucleated cells), no statistically significant differences were identified between patterns and clinical outcome, nor between patterns and (Formula presented.) ; however, the infiltrative pattern was represented more in the poorer outcome group and had higher (Formula presented.) values. When comparing (Formula presented.) and clinical outcome, a statistically significant difference emerged. Cases with poorer outcomes had higher (Formula presented.) values ((Formula presented.) = 192.9) than cases with more favorable outcomes ((Formula presented.) = 120.5), and this association was statistically significant on both univariable and multivariable analyses. This study suggests that (Formula presented.) is highly reproducible and is associated with clinical outcome in csMCTs.