Pancoast Tumor (cont.)
Exams and Tests
The blood exam for persons with Pancoast tumor is not specific, and the results are not diagnostic.
- Chest x-rayM film
- In the early stages, Pancoast tumors are difficult to detect on chest x-ray films because the top of the lung is located in an area of the body that is difficult to visualize clearly on an x-ray film. Shadows (visual interference from nearby body structures) that lie over the lungs make the image on the x-ray film unclear. Many patients end up consulting orthopedic surgeons and neurologists before a definitive diagnosis is made.
- A Chest x-ray film may reveal asymmetry of the tops of the lungs in the form of a small, uniform patch of tissue or pleural thickening (a thickened, abnormal area of tissue) on the apex of one lung. The x-ray film may show a thin plaque (patch of abnormal tissue) at the lung apex in the area of the superior sulcus, or the x-ray film may reveal a large mass, depending on the stage when it is first diagnosed.
- The plain chest x-ray film may show that the tumor has invaded one or more ribs or parts of the vertebrae. Bone destruction 1-3 of the back ribs may sometimes be visible on the x-ray film.
- Enlargement of the mediastinum (area of the chest between the lungs) may be visible on the x-ray film.
- CT scan of the chest: A CT scan helps the doctor determine if the tumor has invaded the brachial plexus, chest wall, mediastinum, vertebra, or a combination thereof. CT images can also reveal involvement of the vena cava, trachea (windpipe), and esophagus (food pipe). Contrast CT scanning, with the help of an injected, radioactive dye that is visible on the scan, is useful for assessing if the tumor has involved the blood vessels under the clavicle (collarbone).
- MRI of the chest: MRI findings are more accurate than CT scan findings in identifying the extent of the tumor involvement. An MRI can also better assess the tumor’s invasion of nearby structures and vertebral bodies and if cord compression is occurring. However, MRI findings have no advantage over CT scan findings in the evaluation of the mediastinum. In fact, CT scan findings are much better than MRI for assessing the mediastinum to determine if the tumor has involved the lymph nodes.
- Arteriogram or a venogram (an x-ray taken after the injection of an opaque [nontransparent] substance into a vessel): Rarely, the Pancoast tumor involves the artery or the vein under the clavicle; therefore, an arteriogram or a venogram may be helpful.
- Bronchoscopy (using a tubular, illuminated instrument for inspecting the airways of the lung) helps evaluate the tracheal and bronchial cavities; however, because most Pancoast tumors form on the periphery of the lung, bronchoscopy does not usually help the doctor make a diagnosis.
- Biopsy (removal of cells for examination under a microscope): Following a biopsy, the doctor can make a diagnosis in 95% of persons based on results from percutaneous (through the skin) needle biopsy, either with the guide of fluoroscopy (procedure using an x-ray machine and a fluorescent screen to view inside the body) or with CT-guided procedures.
- Although more than 90% of patients can be correctly diagnosed based on clinical and radiological findings (chest x-ray, CT, MRI) alone, open biopsy of the tumor for confirmation may be performed through a supraclavicular (above the collarbone) incision. A definite diagnosis is important before proceeding with treatment of the Pancoast tumor. Results from a needle biopsy are also useful in determining the cell type prior to treatment. Even though clinical diagnosis is relatively simple, performing a tissue biopsy is always necessary.
Exams to determine spread
- Among other considerations, CT or MRI of the brain is recommended in the initial evaluation because distant metastases to the brain are not infrequent, and diagnosis of these is necessary for staging.
- Mediastinoscopy: This procedure is performed to determine the extent the tumor has spread into the mediastinum. It is a procedure in which a tube is inserted behind the breastbone through a small cut at the lowest part of the neck. Samples of lymph nodes are taken from this area to look for cancer cells.
- Staging of the cancer is based on scalene (neck muscle) node biopsy results from palpable (capable of being felt) nodes or mediastinoscopy findings.
- Liver and bone scans are performed to determine if the cancer has spread.
- Positron emission tomography (PET) scans (a nuclear imaging technique used to view body functions) may help identify involved lymph nodes and the distant spread of cancer.
Shreekanth V Karwande, MBBS
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