Your pathology report is the document that defines your diagnosis and drives your treatment. It can look intimidating — full of unfamiliar terms — but it follows a logical structure, and learning to read it can help you feel more in control.
Here are the parts you're most likely to see:
- Diagnosis / integrated diagnosis. The headline. In the modern era, this is usually a combined statement of tumor type, grade, and key molecular features — for example, "Astrocytoma, IDH-mutant, CNS WHO grade 3." This single line tells your whole team a great deal.
- Histology. What the tumor cells look like under the microscope, including features like cell density, abnormal nuclei, and whether there's necrosis (dead tissue) or microvascular proliferation (abnormal new blood vessels) — features that traditionally signaled higher grade.
- WHO grade. The grade (1–4), now written in Arabic numerals.
- Molecular results. IDH status, 1p/19q, MGMT methylation, and other markers relevant to your tumor.
- Ki-67 / MIB-1 index. A measure of how many tumor cells are actively dividing — a rough indicator of how proliferative the tumor is. Higher percentages generally suggest more active growth, though it's interpreted alongside everything else.
- Immunohistochemistry (IHC). Stains used to detect specific proteins (for example, IDH1 R132H or ATRX loss) that help classify the tumor.
A few tips. First, don't try to interpret the report alone — the same word can mean different things in different contexts, and your oncologist puts it all together. Second, request a copy of your report and pathology; you're entitled to it, and it's invaluable for second opinions. Third, for serious or unusual diagnoses, a second pathology opinion at an experienced brain-tumor center is reasonable and common.
Reading your report won't replace your care team, but it can turn a frightening mystery into something you can ask informed questions about.