What is a Hypoattenuating Lesion?

A hypoattenuating lesion refers to an abnormality on a CT scan which is darker in density then the surrounding tissues.  We refer to the brightness of a lesion as density.  The term hypoattenuating does not indicate a diagnosis but simply describes an abnormality as being darker then the normal tissues.

What does Hypoattenuating lesion indicate?

Hypoattenuating lesions simply means a dark looking lesion on CT.  Often the radiology physician will also provide additional description of the abnormality seen other then simply saying hypoattenuating.  The term Hypoattenuating lesion is sometimes used in the impression and conclusion of the report.  This is especially true when we do not know what it is and additional testing may be needed.

What can hypoattenuating lesions be?

Hypoattenuating lesions can represent anything from benign abnormalities like cysts which contain fluid to cancerous abnormalities like tumors and metastasis (cancer spread).  The term is used by radiologists to describe the abnormality to someone reading the report.  Hypoattenuating lesions can be found anywhere in the body.

Hypoattenuating lesions in thyroid

An example would be a Hypoattenuating lesion in the thyroid.  This usually refers to a nodule or spot which is darker then the normal thyroid.  This can represent something like a cyst or solid nodule. The radiologist will usually provide more details to help determine whether the Hypoattenuating lesion can be cancerous and needs biopsy.

Hypoattenuating lesions in the abdomen

In the abdomen, Hypoattenuating lesions can be found in any organs.  It is common to see these lesions in the kidneys, pancreas, liver and spleen. Hypoattenuating lesions can represent many diagnosis in these organs.  Other imaging features of these lesions help us make a diagnosis.  Hypoattenuating lesion in these organs tells us nothing about the diagnosis alone.

In the liver, we can see a single or multiple hypoattenuating lesions.  Depending on the appearance, these can represent,cysts, cancer or other diagnosis.  We can not tell the diagnosis from simply hearing they are hypoattenauting.

Hypoattenuating lesions in the pelvis

Hypoattenuating lesions in the pelvis can be seen in organs like the uterus and ovaries.  In the uterus, a Hypoattenuating lesion is most commonly a fibroid.  Hypoattenuating lesions in the ovaries can be cysts or masses.  We often need an ultrasound to tell what an ovarian abnormality is.

Hypoattenuating findings on CT simply tell us that an abnormality is darker then the surrounding normal tissues.  We often need more information to know what the abnormality is.  Additional testing may be needed to include additional imaging tests.  Hypoattenuating is a term used by radiologists, particularly when we are not clear about the diagnosis.