In patients who are having symptoms from this disease, there is often an enlarged spleen felt on physical examination. In the original series published by Dr. Bertha Bouroncle, more than 90% had an enlarged spleen. Subsequently over the years, the finding on an enlarged spleen is more often identified in about 80% of the patients. Therefore, the failure to identify an enlarged spleen does not preclude the diagnosis of hairy cell leukemia. Most patients will have reduced hemoglobin, neutrophiles, and monocytes. Thrombocytopenia is also quite common. A careful examination of the peripheral blood smear will identify the circulating leukemic cells with a serrated cytoplasmic border.

If the physician is planning to find the cause of an enlarged spleen or the reason for an abnormal blood test, you will need to have a physical examination and blood work drawn.

The spleen is located in the upper left side of your abdomen. Sometimes the spleen is enlarged and can be felt by the physician during your examination. It may be necessary for the physician to order a CAT scan of the abdomen to look for the size of the spleen. This study may also show enlargement of lymph nodes that are located in the abdomen.

Your blood work will often show anemia (low red blood cell count), low white blood cell count with abnormal forms of cells, and a low platelet count (that can predispose to bleeding). On reviewing the blood smear, the appearance of cells with hairy borders can be observed. These leukemic cells have a distinct appearance under the microscope. You may also have a reduced number of the normal white blood cells that protect from infection. The absolute numbers of these cells can be useful in determining when treatment should be initiated as well as in establishing the diagnosis.

There are sophisticated studies that can be done on your blood sample to identify certain markers on the surface of the leukemic cells. The markers are called immunophenotype markers. There are characteristic patterns of markers expression that will help to confirm the correct diagnosis.

The physician will likely refer you to a hematologist or oncologist who specializes in the diagnosis and treatment of patients with leukemia. Patients often have a bone marrow biopsy performed that will help in understanding the diagnosis and treatment options. A bone marrow biopsy is performed by using a needle to take a sample of bone from the area near the rear area of your hip. While this is painful, the physician can give both local and other medication to reduce the pain. This procedure is relatively quick, and provides a very useful confirmation of the diagnosis.