How is Kaposi sarcoma diagnosed?
Kaposi sarcoma (KS) is often found when a person goes to the doctor because of signs or symptoms they are having. Sometimes KS may be found during a routine physical exam. If KS is suspected, further tests will be needed to confirm the diagnosis.
Signs and symptoms of Kaposi sarcoma
KS usually appears first on the skin, forming purple, red, or brown patches (not raised above the surrounding skin), plaques (flat areas that are slightly raised), or nodules (bumps) that are called lesions. The skin lesions of KS most often develop on the legs or face, but they can also appear in other areas. Lesions can also develop on mucous membranes such as those inside the mouth. The lesions are usually not painful or itchy. Some lesions on the legs or in the groin area might block the flow of fluid out of the legs. This can lead to painful swelling in the legs and feet.
KS lesions can also sometimes appear in other parts of the body. Lesions in the lungs might block part of an airway and cause shortness of breath. Lesions that develop in the intestines can cause abdominal pain, diarrhea, or bleeding from the rectum.
Medical history and physical exam
If your doctor suspects you might have KS, you will be asked about your medical history to learn about illnesses, operations, your sexual activity, and other possible exposures to Kaposi sarcoma herpesvirus (KSHV) and HIV. The doctor will ask you about your symptoms and about any skin tumors you have noticed.
As part of a complete physical exam, the doctor will examine your skin and the inside of your mouth to look for KS lesions. Sometimes KS lesions develop inside the rectum (the part of the large intestine just inside the anus). A doctor might be able to feel these lesions during an exam with a gloved finger. The doctor may also check the stool for occult (unseen) blood, since KS in the intestines can cause bleeding.
To be sure that a lesion is caused by KS, the doctor will need to take a small sample of tissue from the lesion and send it to a lab to be analyzed. This is called a biopsy. A specially trained doctor called a pathologist can often diagnose KS by looking at the cells in the biopsy sample under a microscope.
For skin lesions, the doctor will usually perform a punch biopsy, which removes a tiny round piece of tissue. If the entire lesion is removed, it is called an excisional biopsy. These procedures can often be done with just local anesthesia (numbing medicine).
Lesions in other areas, such as the lungs or intestines, can be biopsied during other procedures such as bronchoscopy or endoscopy, which are described below.
The lungs may be x-rayed to see if KS is there. If the x-ray shows something abnormal, other tests might be needed to tell for sure if it is KS or some other condition.
If someone is known to have KS in the lung, chest x-rays can be used to see how the disease is responding to treatment.
Bronchoscopy lets the doctor look into the windpipe (trachea) and the large airways of the lungs. This procedure is often done if the patient is having problems such as shortness of breath or coughing up blood, or if the chest x-ray shows something abnormal. Any of these could mean that KS is in the lungs.
Before starting the bronchoscopy, the patient is put to sleep with a light anesthesia. Then the doctor inserts the bronchoscope (a thin, flexible lighted tube with a small video camera on the end) through the mouth, down the windpipe, and into the lungs. If the doctor sees an abnormal area that might be KS, it can be biopsied through the bronchoscope. Bronchoscopy with biopsies can also be used to help diagnose other lung problems seen in AIDS patients, such as pneumonia.
One or more of these tests might be done when the doctor suspects that KS is in the stomach or intestines and is causing problems.
- Upper endoscopy (also called esophagogastroduodenoscopy, or EGD) is used to look at the inner lining of the esophagus, the stomach, and the first part of the small intestine. For this procedure, the patient is first given drugs to make them sleepy. Then, the doctor guides the endoscope (a thin, flexible, lighted tube with a small video camera on the end) through the mouth and esophagus and into the stomach and small intestine. This lets the doctor see things like ulcers, infections, and KS lesions. If an abnormal area is seen, the doctor can use small surgical instruments through the endoscope to biopsy it.
- Colonoscopy is used to look inside the large intestine (colon and rectum). Before this test can be done, the colon and rectum must be cleaned out to remove any stool. This often means drinking a large amount of a liquid laxative the night before and the morning of the procedure. Sometimes enemas are used as well. Just before the procedure, the patient is given intravenous (IV) medicine to make him or her relaxed or even asleep. Then a colonoscope (a long, flexible, tube with a light and video camera on the end) is inserted through the rectum and into the colon. Any abnormal areas seen can be biopsied.
- Capsule endoscopy is a way to look at the small intestine. It is not truly a type of endoscopy, since it doesn’t use an endoscope. Instead, the patient swallows a capsule (about the size of a large vitamin pill) that contains a light source and a very small camera. Like any other pill, the capsule goes through the stomach and into the small intestine. As it travels through the small intestine (usually over about 8 hours), it takes thousands of pictures. These images are transmitted electronically to a device worn around the person’s waist while he or she goes on with normal daily activities. The images can then be downloaded onto a computer, where the doctor can look at them as a video. The capsule passes out of the body during a normal bowel movement and is discarded. A disadvantage of this test is that it doesn’t allow the doctor to biopsy any abnormal areas.
- Double balloon enteroscopy is another way to look at the small intestine. Regular endoscopy cannot look very far into the small intestine because it is too long and has too many curves. This method gets around these problems by using a special endoscope that is made up of 2 tubes, one inside the other. The patient is given intravenous (IV) medicine to make him or her relaxed, or even asleep. The endoscope is then inserted either through the mouth or the anus, depending on if there is a specific part of the small intestine to be examined. Once inside the small intestine, the inner tube, which has the camera on the end, is advanced about a foot as the doctor looks at the lining of the intestine. Then a balloon at its end is inflated to anchor it. The outer tube is then pushed forward to near the end of the inner tube and is anchored in place with a second balloon. This process is repeated over and over, letting the doctor see the intestine a foot at a time. The doctor can even take a biopsy if something abnormal is seen. This procedure is more involved than capsule endoscopy (and may take as long as 2 hours to complete), but it has the advantage of letting the doctor biopsy any lesions seen.
KS can also affect other organs, such as the liver, spleen, heart, or bone marrow. These areas do not often need to be biopsied if the patient is already known to have KS based on biopsies of other tissues, such as skin, lungs, or intestines.
Last Medical Review: 02/20/2013
Last Revised: 02/20/2013