There are numerous possible causes of a lump or mass in the stomach. A person may be able to feel the mass, or it might only be detectable with imaging or other diagnostic tests.

In this article, we cover some of the common causes of a mass in the stomach and the other symptoms that a person may experience. We also explain when a person should see a doctor.

A CT scan, which can reveal a mass in the stomach.Share on Pinterest
Imaging studies, an upper endoscopy, and blood tests can all help reveal the underlying cause of a mass in the stomach.

There are many possible causes of a mass in the stomach. Some examples of these causes include:

Abdominal aortic aneurysm

An abdominal aortic aneurysm (AAA) is a medical condition that causes a weak area to develop in the abdominal aorta, which is a large blood vessel in the abdomen that brings oxygen-rich blood to the heart. If an AAA is too large, it has the potential to rupture, which can cause severe and life threatening bleeding.

Symptoms: Most of the time, an AAA does not cause symptoms. However, a person may sometimes detect a pulsatile —meaning that it beats like the heartbeat — mass in the stomach. In the emergency event that a AAA ruptures, a person may experience a sudden, severe stomach pain and loss of consciousness.

Abdominal liposarcoma

Abdominal liposarcomas are a type of cancer that grows from fat cells in the body, including those at the back of the abdomen.

Symptoms: A person may experience stomach pain, abdominal swelling, indigestion, abnormal bowel movements, weakness, nausea, or vomiting.

Abdominal schwannoma

Abdominal schwannomas are a very rare type of tumor that grows from nervous system cells called Schwann cells. While these often grow in the spinal cord or other places in the central nervous system, they can grow in the stomach.

Symptoms: These may include a palpable abdominal mass that is tender to the touch, stomach pain, and a feeling of fullness in the abdomen.

Stomach cancer

Gastrointestinal stromal tumors usually grow in the stomach wall or the small intestine. Stomach cancer tumors are often small and relatively slow growing, so people may not be able to feel them.

Symptoms: These may include bloody bowel movements, stomach pain, abdominal swelling, nausea, feeling full after eating a small amount of food, appetite loss, and unexplained weight loss.

Abdominal masses

The stomach sits in the abdominal cavity, which is the space between the chest and pelvis. While masses can appear in the stomach itself, some conditions cause masses elsewhere in the abdominal cavity, such as in the intestines, kidneys, or liver.

Examples of conditions that can cause abdominal masses include:

In addition to feeling a lump or growth, a person with a stomach mass may experience some of the following symptoms:

  • abdominal bloating
  • stomach discomfort or pain
  • blood in the stool that may appear dark or bright red
  • feeling full even after eating just a small amount
  • nausea

The symptoms are likely to depend on the underlying condition that is causing the stomach mass.

A doctor will first diagnose a mass in the stomach by asking the person about their symptoms and medical history. They may then order diagnostic tests. Examples of these tests include:

  • Imaging studies: Imaging studies such as CT, MRI, or ultrasound scans can help a doctor detect or determine the size of a mass. Each imaging type has different capabilities in terms of identifying stomach masses.
  • Upper endoscopy: This diagnostic test involves using a lighted scope with a camera on the end to examine the esophagus (food pipe), stomach, and first part of the small intestine. A doctor may be able to see the mass and take tissue samples from it.
  • Blood tests: A doctor may order blood tests, such as a complete blood count or fecal occult blood test. If a person has low blood counts or hidden blood in the feces, this could indicate that they are losing blood via a tumor or other mass.

Sometimes, a stomach mass is an incidental finding, which means that a doctor discovers it while a person is having an imaging scan or other medical test for another purpose.

It can be easy to mistake a stomach mass for other medical conditions. Examples of conditions that may seem like a stomach mass include:

  • Hernias: Protrusions of tissue or intestine through the abdominal wall.
  • Lipomas: These lumps on the skin may be due to an excess of fat cells. A lipoma is different than a liposarcoma because it is not cancerous and usually feels softer and more movable to the touch.
  • Uterine fibroids: These noncancerous tumors grow from the muscle layers of the womb. If a fibroid is large enough, a person may mistake it for an abdominal mass.

A doctor can use diagnostic testing to determine whether an abdominal mass is due to a condition outside or inside the stomach.

The underlying cause of a stomach mass will determine the treatment options. A doctor will also consider a person’s symptoms and overall health when deciding on the best treatment.

A doctor may recommend surgically removing the mass, even if it is noncancerous. If the mass grows, it could potentially affect blood flow to the stomach.

If the mass is cancerous, a doctor may recommend radiation therapy to shrink the stomach mass. If possible, a surgeon will then remove the mass.

The possible complications of a mass in the stomach depend on the underlying cause and the size of the mass. If the mass is cancerous, it is possible that cancerous cells could travel to other locations in the body.

A stomach mass can be a serious medical condition. The mass can lead to bleeding, problems eating, and pain. A person should talk with their doctor about potential complications and their outlook based on their diagnosis.

A person should see a doctor if they notice a mass in their stomach. Some people may not be able to feel a mass but might notice other related symptoms, such as:

  • appetite loss
  • problems eating
  • unexplained stomach pain
  • unintentional weight loss

If a person experiences persistent or severe stomach-related symptoms, they should see a doctor.

Several different medical conditions can cause a mass inside or outside the stomach.

There are also medical conditions that affect the abdomen and lead to a mass or masses elsewhere in this part of the body.

If a person is concerned about their stomach-related symptoms, they should see a doctor.