Mitotic Index
The number of mitotic figures per unit area in histologic examination, used for grading neuroendocrine tumors.
Full Definition
The mitotic index, typically expressed as mitoses per 10 high-power fields (HPF) or per 2 mm², is a key histopathologic parameter used in the grading and classification of neuroendocrine tumors. Along with the Ki-67 proliferation index, it helps determine tumor grade (G1, G2, or G3) according to WHO classification schemes. A higher mitotic index generally correlates with more aggressive tumor behavior and poorer prognosis. Pathologists must carefully count mitotic figures in the most proliferatively active areas of the tumor to ensure accurate grading.
Usage
Usage note: Always specify the counting method (per 10 HPF or per 2 mm²) for clarity.
In Context
- "The pancreatic neuroendocrine tumor showed a mitotic index of 8 per 10 HPF, consistent with grade 2 classification." — Pathology report
- "Mitotic index and Ki-67 staining were both elevated, supporting a diagnosis of poorly differentiated neuroendocrine carcinoma." — Histopathology assessment