Is Hairy Cell Leukemia a Chronic Lymphocytic Leukemia (CLL)?

Chronic lymphoid leukemia (CLL) is an oncohematological entity included in the chronic lymphoproliferative syndromes characterized by an increase in a dysfunctional lymphoid population; it is the most common leukemia in western countries. On the other hand, hairy cell leukemia is a different pathology; however, both share certain characteristics in common. So, hairy cell leukemia is not a chronic lymphocytic leukemia.

Chronic lymphocytic leukemia is a type of chronic lymphoproliferative syndrome with leukemic expression.

CLL is a cancer of the blood in which the bone marrow and organs of the lymphatic system produce too many B lymphocytes, a type of white blood cell. Under normal conditions, B and T lymphocytes are responsible for fighting infections, either by producing antibodies that attack the harmful elements that invade or occur in our body (B lymphocytes), or attacking them directly (T lymphocytes).

In CLL, B lymphocytes progressively infiltrate the bone marrow, lymphatic tissues (lymph and spleen mainly) and other organs such as the liver. The clinical manifestations of the disease are a consequence of this infiltration that displaces the normal elements of the blood and prevents the proper functioning of the affected organs. Additionally, the produced lymphocytes do not function correctly and cannot fulfill their mission of defense of the body.

Usually, CLL affects people over 60 years of age (median age is 70 years, only 20% are under 65), being extremely exceptional in children, and progresses very slowly. In many cases, people suffering from this disease have no symptoms for years. It is only leukemia in which a higher incidence among family members has been described (5%).

Symptoms and Diagnosis of CLL

In more than 80% of the patients, the CLL is diagnosed by a routine analysis or by chance, since they are usually totally asymptomatic.

In the remaining cases, the main symptoms can be asthenia (weakness, lack of energy and strength), lymphadenopathy (enlarged lymph nodes) and repeated infections. It is not strange that there is splenomegaly (inflammation of the spleen) or hepatomegaly (enlargement of the liver) that can cause abdominal discomfort. Unlike what happens in lymphomas, fever, night sweats and weight loss are not frequent (10%).

To establish the diagnosis of CLL, the morphological and immunophenotypic study of the blood is sufficient, although the study is usually completed by examining the bone marrow, obtained by means of a puncture of the sternum or the bone of the hip. For correct assessment, their cytogenetic and molecular characteristics must also be analyzed. It is also usual to study which ganglion territories are affected by imaging techniques (radiographs, ultrasound, scintigraphy, scan or magnetic resonance).

Treatment of Chronic Lymphocytic Leukemia

Patients with an early-stage CLL usually do not require treatment for years and can lead a normal life, except for the periodic controls they are required to control if the disease progresses or remains stable. The criteria for starting treatment are the presence of:

Very evident systemic symptoms (fever, sweating, weight loss).
Adenopathies or splenomegaly of large size that causes discomfort to the patient.
Recurrent infections.
Progressive increase in anemia and/or thrombocytopenia (low levels of platelets).
Time of duplication of lymphocytes very fast (less than 12 months).
Very high lymphocyte counts are not, by themselves, a criterion for starting treatment.

These patients should receive treatment with one of the multiple chemotherapy regimens currently used, based mostly on a highly effective agent called fludarabine that is associated with other chemotherapeutic agents (cyclophosphamide, mitoxantrone, chlorambucil, bendamustine, etc.) or a biotherapeutics agent such as rituximab.

Unlike other leukemias, CLL is not usually treated with a transplant of hematopoietic progenitors due to the advanced age of most patients. However, young patients with aggressive CLL may benefit from this therapeutic measure if they have a histocompatible donor, as this is the only therapy that allows the disease to be cured. Currently, experts are starting to treat, with hopeful results, older patients who have a donor compatible with a new modality of hematopoietic transplant, the so-called reduced intensity transplants.

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Is Hairy Cell Leukemia a Chronic Lymphocytic Leukemia (CLL)?