PNI is an acronym used in oncology, but its meaning depends on the clinical context. Most commonly, PNI refers to **perineural invasion**, a pathology finding where cancer cells are seen around or within nerves. PNI can also mean **prognostic nutritional index**, a calculated score based on blood tests that reflects nutrition and immune status. Both forms of PNI are used in cancer care to help describe risk and guide clinical discussions.

Perineural invasion is a pathology finding where cancer cells are seen tracking along or around a nerve. It is most often identified under the microscope in biopsy or surgery specimens. Clinicians use it as a feature that can help describe how a tumor is behaving locally. It commonly appears in pathology reports for several solid tumors, especially in the head and neck, skin, pancreas, prostate, and colorectal region.

LVI stands for lymphovascular invasion. It means cancer cells are seen inside lymphatic channels or blood vessels under the microscope. LVI is most commonly reported on a pathology report after a biopsy or surgery. Clinicians use it as one piece of information to understand cancer behavior and guide planning.

Lymphovascular invasion is a pathology finding where cancer cells are seen inside lymphatic channels or small blood vessels. It is identified under the microscope in tissue removed by biopsy or surgery. It helps clinicians understand how a tumor may spread beyond its original site. It is commonly discussed in surgical pathology reports and cancer staging or risk assessment.

R2 resection is a surgical margin classification used in oncology. It means the surgeon removed tumor tissue, but visible (macroscopic) cancer remains after the operation. R2 resection is commonly discussed in surgical oncology, pathology reports, and tumor board planning. It helps the care team describe how complete the surgery was and what additional treatment may be needed.

R1 resection is a surgical pathology term that describes a cancer operation where tumor cells are found at the cut edge (the “margin”) under a microscope. In plain terms, it means the tumor was removed, but microscopic cancer may still be left behind at the surgical boundary. It is commonly used in surgical oncology reports for solid tumors, alongside R0 (clear margins) and R2 (visible residual tumor).

R0 resection means a tumor has been surgically removed with **no cancer seen at the cut edges (margins) under a microscope**. It is a standard term used in **surgical oncology** and **pathology reports** for many solid tumors. R0 resection describes the **quality of tumor removal**, not a specific surgical technique.

Margins are the edges or borders of tissue around a tumor. They are most commonly discussed after cancer surgery and in the pathology report. Margins help describe whether tumor cells extend to the cut surface of the removed tissue. They are also used in radiation oncology and some ablation procedures to define treatment boundaries.

Tumor differentiation describes how closely cancer cells look and behave like the normal cells they came from. It is usually reported by a pathologist after a biopsy or surgery. It helps summarize how “mature” or “specialized” the tumor cells appear under the microscope. It is commonly used in pathology reports, tumor grading, and treatment planning discussions.

Mitotic index is a measure of how many cells in a tissue sample are actively dividing. It is commonly assessed by a pathologist when a biopsy or surgery sample is examined under a microscope. In cancer care, it helps describe how quickly a tumor may be growing. It is often reported as part of a tumor’s grade or risk assessment.