Metastatic Bone Lesions on CT

Metastatic bones lesions are identified when a cancer has spread from its primary site.  Metastatic cancer has a worse prognosis.  Metastatic cancer can spread to many places throughout the body including the organs, brain, lungs, and bones.

What cancers go to bones?

CT scans are commonly used to both stage and follow all types of cancers.  CT can often show bone abnormalities related to cancer.  The normal bone will be replaced with cancerous lesions.  All types of cancers can go to the bones.  Some common ones include breast, prostate, lung and kidney.

What does cancer look like on CT?

Cancerous lesions can look sclerotic or whiter then normal bone.  They can also be lytic which means the bone lesion is lighter then normal bone.  This looks like a hole in the bone.   Some bone lesions are not identified on CT.  Other tests like bone scan and PET scan may be better.

Can we say where the cancer came from?

Metastasis on CT do not tell us the origin of the cancer.   Some bone lesions are more likely to be sclerotic or whiter then normal bone.  Some of these include prostate and breast cancer.  Other lesions are more likely to be lytic or like a hole.  Some of these are kidney and thyroid.   There is however overlap.

Some benign lesions can look like metastasis on CT in the bones. Therefore, a biopsy may be needed if the bone lesion being cancer changes the management or treatment.   Multiple bone lesions in the skeleton are more likely to be cancerous.  This is especially true if there is already a diagnosis of cancer known.

What other tests are done for bone metastasis?

Further evaluation of skeletal or bone metastasis is often done with bone scan.  This is a nuclear medicine test where a small amount of radioactive pharmaceutical is injected into the vein and the body is scanned.  This is a test that allows us to survey the entire skeleton from skull to toes.  This test is best for detecting metastasis which causes bone turnover and those which are sclerotic.  One downside is that this test detects many other abnormalities which can look cancerous like fractures, infections and bone tumors.

PET scans are also often used to stage cancer.  They are good for detecting all kinds of bone lesions.  The test also detects cancer all throughout the body.  The test uses a radioactive sugar to go where it is used most.  The idea being that cancer uses more sugar then normal tissues in the body.

Metastasis in the bone on CT can be detected and can impact management and treatment.  They can be lytic in appearance or sclerotic.  Many different kinds of cancers can go to the bone.  We can’t tell what the cancer is by looking at the bone lesion.  Some benign bone lesions can also look like cancer.  Further testing may be needed including biopsy.