Chronic lymphocytic leukemia diagnosis
The most important part of the diagnosis in chronic lymphocytic leukemia is a complete blood cell count. In some cases, it is the only way to diagnose the disease because patients are asymptomatic and the discovery is nothing but casual. Tests will show lymphocytosis, and blood cell count usually reaches 5000 B-lymphocytes per microliter or more. The diagnosis is made by looking at the signs and symptoms and performing another test after 3 months, which shows the same type of lymphocytosis.
In some cases, patients have fewer than 5000 B-lymphocytes per microliter with swollen lymph nodes, and differential diagnosis should be made with small lymphocytic lymphoma. In these cases, it is necessary to confirm the diagnosis through a lymph node biopsy.
It is also important to perform a microscopic examination of the peripheral blood to confirm lymphocytosis. There will be around 50% of large and cleaved lymphocytes, but more than that is usually due to another type of leukemia, called prolymphocytic leukemia.
Other tests such as flow cytometry should be done to confirm clonality. It is useful to check the presence of surface proteins such as CD20, CD23, CD5, and CD19.
In patients with recurrent infections, it will be necessary to perform immunoglobulin tests and consider the administration of monthly immunoglobulin in patients with lower than 500 mg of IgG.
Another differential diagnosis includes hairy cell leukemia. This type of leukemia has positive surface immunoglobulin, and it is negative for certain surface proteins, including CD21 and CD5.
It may be necessary to perform a bone marrow aspiration, especially when trying to diagnose complicated cases of chronic lymphocytic leukemia. In the majority of cases, it is not required. Other tests usually performed in the diagnostic phase and later on include an abdominal ultrasound to detect liver or spleen enlargement.