reactive zone
The rim of normal tissue surrounding a tumor that shows inflammatory and healing responses to the adjacent malignancy.
Full Definition
The reactive zone represents the interface between tumor and normal tissue, characterized by inflammatory infiltration, increased vascularity, fibroblast proliferation, and other healing responses triggered by the presence of malignant tissue. This zone is distinct from true tumor extension but may contain microscopic tumor cells and inflammatory mediators that could promote tumor growth. In surgical planning, the reactive zone must be considered when determining adequate margins, as leaving reactive tissue behind may contribute to local recurrence. The width and characteristics of the reactive zone vary depending on tumor type, grade, and host response factors.
Usage
Usage note: Not synonymous with tumor margin, as it represents host response rather than tumor extent.
In Context
- "Histologic examination revealed tumor cells scattered throughout the reactive zone." — Pathology report
- "The reactive zone demonstrated increased enhancement on contrast-enhanced MRI." — Imaging interpretation