Fig. 24.
Increased mitotic activity in adrenal cortical carcinomas. In adrenal cortical pathology, increased mitotic activity is defined when an adrenal cortical tumor shows a mitotic count that exceeds 5 mitoses per 10 mm2 (50 high-power fields). This cutoff has been widely applied in all traditional multiparametric diagnostic schemes in adults. A mitotic count that exceeds 15 mitoses per 4 mm2 (20 high-power fields) has been used in pediatric manifestations. This composite photomicrograph illustrates increased mitotic activity in a conventional adrenal cortical carcinoma (A). Mitotic figures are circled. PhosphoHistone-H3 immunohistochemistry (B) may facilitate mitotic count in low-grade adrenal cortical carcinomas. This biomarker also facilitates the distinction of mitotic figures from apoptotic figures and may also help identify atypical mitotic figures