Difference Between Lesion and Tumor

Certain medical term scare patients; cancer, malignant, tumor, lesion and growth are a few of those important terms. However, this fear is groundless in many cases. While “cancer” and “malignant” truly refer to something bad, the terms “tumor” and “lesion” only mean that there is some abnormality.  Even the term cancer should not scare people because many cancers are slow-growing and minimally invasive. They can be removed completely by surgery to a point where no residual cancer is present.  However, this article intends to discuss in detail what lesion and tumor are, how they differ, and what they refer in different contexts.

What is Lesion?

Lesion is a general term used to refer to an abnormal region of tissue. It can be anything from a localized redness to widespread cancer. It can be a wound, acutely inflamed area, burn, a congenital structural abnormality etc. It can be visible to the naked eye or be microscopic.  The term lesion does not give a hint towards prognosis.

Here is a clinical scenario to explain the use of the word. When a patient presents with clear vaginal discharge not associated with periods, itching or drugs the gynecologist will do a vaginal examination. He might notice an abnormal area on the cervix. It may be something simple or sinister. The doctor does not know yet. He might write down on his notes that there is a “lesion” on the anterior lip of the cervix, about 1 centimeter in diameter, which bleeds on contact, without parametrium thickening. This lesion should not be misunderstood to be something bad at this point. It refers to an abnormality alone. Then the doctor may take a biopsy then and there or in theatre under anesthesia. The sample will be sent for tissue analysis. The report will tell if it is benign or malignant. The doctor may still use the word lesion, but now with histological analysis the words tumor, cancer, or growth may be more appropriate. Even if it is cancer the doctor may refer to it as “the lesion” to avoid alarming you or while in the company of others.

What is Tumor?

Tumor is an abnormal growth of tissue. It may be congenital or acquired. It may be visible to the naked eye or can be microscopic. Tumors may or may not compress surrounding tissues. This term also does not give an idea about the prognosis. Uterine fibroid is a benign tumor of the uterus. It does not spread or invade tissues. On the other end of the spectrum, malignant melanoma is a highly invasive tumor of the skin. See the use of the word “tumor” in the last three sentences. It was used to refer to both the sinister one and the simple one.

Pituitary micro-adenoma is a microscopic tumor of the anterior pituitary. It secretes prolactin and gives whitish breast discharge but does not cause any visual symptoms. Macro-adenomas of anterior pituitary compress the optic chiasma and gives bi-temporal hemianopia, in addition to whitish breast discharge. Here, the term “tumor” was used regardless of the size of the growth.

What is the difference between Lesion and Tumor?

• Lesion refers to any abnormal area of tissue while tumor more specifically refers to an abnormal outgrowth of tissue.

• Either one does not hint towards prognosis.

• Either one does not hint towards the site, size, shape or other characteristics.


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