Poorly Differentiated
A histologic grade indicating high-grade neuroendocrine tumors with aggressive behavior and poor prognosis.
Full Definition
Poorly differentiated is a histopathologic classification for high-grade neuroendocrine tumors (Grade 3) characterized by high mitotic rates, elevated Ki-67 proliferation indices, and lack of organized neuroendocrine architecture. These tumors typically have mitotic counts exceeding 20 per 10 HPF and Ki-67 indices greater than 20%. Poorly differentiated neuroendocrine carcinomas are distinguished from well- and moderately-differentiated neuroendocrine tumors by their aggressive clinical behavior, tendency for early metastasis, and generally poor response to conventional NET therapies. They often require platinum-based chemotherapy regimens similar to those used for other high-grade carcinomas.
Usage
Usage note: Hyphenate when used as a compound adjective before a noun.
In Context
- "Histologic examination revealed a poorly differentiated neuroendocrine carcinoma with extensive necrosis." — Pathology report
- "The poorly differentiated tumor required aggressive chemotherapy rather than standard somatostatin analog therapy." — Treatment planning