A hypoechoic mass is tissue in the body that’s more dense or solid than usual. This term is used to describe what is seen on an ultrasound scan. Ultrasound uses sound waves that are absorbed by or bounce off of tissues, organs, and muscles. The waves form the black and white image you see on an ultrasound screen.

Ultrasound is a useful tool to see if any part of your body has changed from its baseline state. One tissue type may have a different echogenicity than another. This is the amount of sound waves that are reflected or echoed back.

A change may show up as hypoechoic or hyperechoic. These masses differ in a number of ways:

Hypoechoic massHyperechoic mass
more solidless dense
less echogenic (absorbs more ultrasound waves)more echogenic (reflects more ultrasound waves)
appears gray or darker than surrounding tissueappears lighter or brighter than surrounding tissue
made up of muscle or fibrous connective tissuemay be air-, fat-, or fluid-filled

A hypoechoic mass can form anywhere in the body. It has a number of causes, including harmless ones.

A hypoechoic mass may be a tumor or abnormal growth. It may be benign or malignant. A benign tumor may grow but it will not spread (metastasize) to other organs. A malignant (cancerous) tumor can spread and invade other parts of the body.

In some cases, an ultrasound scan may be the first exam to check organs and tissues. It acts like a flashlight beam that shows shapes and shadows inside the body. An ultrasound cannot tell whether a hypoechoic mass is benign or malignant, or what has caused it.

If you have a hypoechoic mass, your doctor may recommend other tests to learn more about it, including:

  • CT scan
  • MRI scan
  • mammogram
  • biopsy
  • blood tests
  • follow-up ultrasound scans

Scans show features which may indicate a cancerous mass, such as:

  • a shadow or halo appearance
  • a fuzzy or irregular outline rather than smooth
  • a branching or starburst pattern
  • an angular shape rather than rounded or oval
  • fading rather than a uniform shade
  • fast growth
  • calcifications
  • tentacle-like growths
  • blood vessels in or around it

Breast

Breast cancer is the second leading cause of cancer-related death in women. Regular breast exams and screening are important. However, most growths found in the breast are benign. Most benign and malignant masses in the breast are hypoechoic.

Some benign masses in the breast can look like cancer because they have similar features.

Causes of benign hypoechoic masses in the breast include:

Other causes of benign masses include infections, trauma, and inflammatory conditions due to:

Some malignant breast tumors are:

  • invasive ductal carcinoma
  • invasive lobular carcinoma
  • inflammatory breast cancer

Cancerous hypoechoic masses of the breast will typically have distinct characteristics, such as:

  • being deeper or taller than they are wide
  • having a duct extension
  • having both hypoechoic and hyperechoic lines radiating from its surface

Liver

Hypoechoic masses in the liver are commonly discovered during scans of the abdomen. They typically form as a single spot in the liver, but some people may have more than one. More than 20 percent of adults have a benign liver hypoechoic mass. They can occur in a healthy liver and may not cause symptoms. Some benign types are:

A cluster of hypoechoic masses in the liver may be caused by cancer that has spread from another part of the body. This is called liver metastasis. Other malignant causes include:

Kidney

Ultrasound scans are particularly important in examining the kidneys, and changes in the tissues can be easily seen.

Almost 25 percent of hypoechoic masses in the kidneys are benign (noncancerous) or indolent (grows slowly) cancer, such as:

  • oncocytoma
  • angiomyofibroma

The most common malignant tumor in the kidney is renal cell carcinoma. It makes up almost 86 percent of all cancers of the kidney. This growth can be a hypoechoic mass.

Other cancerous hypoechoic masses in the kidneys include:

  • adenocarcinoma
  • clear cell carcinoma
  • kidney metastasis
  • papillary renal cell carcinoma
  • squamous cell carcinoma
  • transitional cell carcinoma
  • Wilms tumor

Uterus

Fibroids, also called leiomyomas or myomas, are common growths in the uterus. They show up as hypoechoic masses on an ultrasound. These benign tumors may occur in almost 70 percent of women by the age of 50. Fibroids are solid masses that are normally made up of fibrous connective tissue and smooth muscle. Most women with fibroids will have more than one.

Other types

In the pancreas, cancerous tumors and a benign condition called pancreatic and peripancreatic tuberculosis (PPT) are hypoechoic on an ultrasound.

Hypoechoic masses can also form in the:

Ultrasound waves cannot see through the skull and other bony areas as well as they can in softer, tissue areas. The lungs are also difficult to view with an ultrasound because they’re air-filled. Other scans are commonly used to check for tumors in these areas.

Treatment for a hypoechoic mass depends on the type, size, location, and symptoms.

Wait and see approach

You may not require treatment at all. In some cases, the underlying infection, inflammation, or condition may be treated. Or, a hypoechoic mass may shrink on its own. Your doctor may take a wait-and-see approach if it’s safer to carefully monitor the mass instead of removing it.

Surgery

Surgery may be the best option to remove larger hypoechoic masses. Benign growths can cause pain, obstruction, and other complications. In some cases, a benign mass may become cancerous, or rupture and cause bleeding inside the body. Masses that affect organs, blood vessels, and nerves are commonly removed. Others may be removed for cosmetic reasons.

Tumor surgery may be done with a keyhole, laparoscopic, or endoscopic procedure. This technique requires tiny surgical incisions or none at all. Some masses may require traditional open surgery.

Ablation

Radiofrequency ablation is another less invasive procedure that shrinks masses with electrical currents.

If there’s any doubt about a diagnosis, your doctor may recommend surgery to remove it. Removing a mass is one way to help reduce the risk of cancer.

Additional treatment

Hypoechoic masses that are diagnosed as malignant require more aggressive treatment. This includes surgery, radiation therapy, chemotherapy, and other cancer treatments.

Healing time and expectations

Healing time depends on the type of tumor and treatment. You may require pain management, as well as antibiotics to reduce the risk of infection after some procedures.

Hypoechoic masses that are benign don’t normally grow back once they’re removed. Malignant tumors can sometimes grow back even after surgery and treatment. Follow-up scans help to ensure that if there is a new growth, it’s caught and treated as early as possible.

A hypoechoic mass is a nonspecific finding that means you may need further tests. It’s not a measurement or a diagnosis. Ultrasound is an important medical tool that helps doctors detect abnormalities and determine what should be done next.

Your doctor will consider your medical history, physical examination, current symptoms, and all other necessary scans and tests before making an evaluation.

Immediately inform your doctor if you have any signs or symptoms, such as:

  • discomfort or pain
  • tenderness
  • bloating or gassiness
  • fatigue
  • chills
  • fever
  • night sweats
  • loss of appetite
  • weight loss
  • nipple discharge
  • a lump or thickened area
  • skin changes such as a rash or sore
  • blood in the urine or stool
  • excessive menstrual bleeding

See your doctor if you feel or see anything out of the ordinary. Regular checkups are important, because you may not have any symptoms at all. Early detection increases the chances of successful medical treatment.