Doctors use many tests to diagnose a tumor and find out if it is cancerous, and if so, whether it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of tumors, a biopsy is the only way to make a definitive diagnosis. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the tumor has metastasized. 

The diagnosis of PPB depends on an examination under a microscope of material from inside the chest, either cyst material or solid tumor tissue. In Type I (cystic) PPB, the cysts appear only slightly abnormal, but very close evaluation shows that the walls of the cysts contain very small collections of cancerous cells. In Types II and III PPB, it is obvious when looking under a microscope that tissue inside the chest is cancerous, but, because PPB is so rare, it may be difficult for the doctors to determine exactly what type of tumor it is. Often, doctors will send tissue samples to other experts for help determining the correct diagnosis.

In addition to a physical examination, the following tests may be used to diagnose PPB:

Biopsy [2]. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that a tumor is present, but only an examination of a piece of the tumor can make a definite diagnosis. The sample removed during the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluates cells, tissues, and organs to diagnose disease).

X-ray. An x-ray is a way to create a picture of the structures inside of the body using a small amount of radiation.

Computed tomography (CT or CAT) scan [3]. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail. After a chest x-ray shows something abnormal in the lungs, a CT scan is the best method for obtaining more information.

Magnetic resonance imaging (MRI) [4]. An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture. MRI is not a very good way to look inside the chest, but it is often the best test for looking at other parts of the body to determine if the tumor has spread.

Bone scan [5]. A bone scan uses a radioactive tracer to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears gray to the camera, and areas of injury, such as those caused by a tumor, appear dark.

Learn more about what to expect when having common tests, procedures, and scans [6].

After these diagnostic tests are done, your child’s doctor will review all of the results with you. If the diagnosis is a tumor, these results also help the doctor describe the tumor; this is called staging [7]. Learn more about the first steps to take after a diagnosis of a tumor [8].