A tumor of uncertain malignant potential is a tumor that a pathologist cannot clearly call benign or malignant. It has some worrisome features, but not enough to diagnose cancer. Most of these tumors behave like benign tumors. A small number come back after removal or, rarely, spread.
This article explains what this diagnosis means, which tumors receive it, how doctors treat them, and what your report may say.
Uncertain malignant potential means the pathologist cannot confidently predict how the tumor will behave. A benign tumor stays in one place and does not spread. A malignant tumor, or cancer, can grow into nearby tissue and spread. A tumor of uncertain malignant potential has features of both. The term describes this uncertainty honestly. It is not a vague diagnosis.
The pathologist decides whether a tumor is benign or malignant by looking at specific features under the microscope. Each tumor type requires certain features. A tumor receives this label when it shows some of them, but not enough. The key features include:
Doctors use this term for specific tumor types. Each has its own rules. Examples include:
The two terms describe a similar idea. Both mean a tumor between benign and malignant. The term used depends on the organ. In the ovary and for phyllodes tumors of the breast, pathologists say borderline tumor. Examples include serous borderline tumor of the ovary and borderline phyllodes tumor. For the tumors listed above, pathologists describe them as having uncertain malignant potential.
Surgery to remove the whole tumor is the main treatment. For most of these tumors, surgery alone is enough. Chemotherapy and radiation are not usually needed. Because a small risk remains, doctors usually recommend regular follow-up.
Uterine STUMP shows how this works. About 1 in 10 come back, and a recurrence is more often another STUMP or a fibroid than a cancer. Follow-up often means an exam and an ultrasound every six months for five years, then once a year. Teams differ in their exact plans.
Reports describe these tumors in a few standard ways. Each laboratory phrases them a little differently: