Juan Carlos Dupont

Chronic leukemias comprise a group of malignant hematological diseases characterized by an increase in the number of circulating leukocytes, a variable increase in the size of the spleen, and a variable alteration in the number of erythrocytes and platelets.

Chronic leukemias are more common in adults. Chronic myeloid leukemia (CML) is rare in children, and its incidence increases around the age of 45. Chronic lymphocytic leukemia (CLL) is rare before the age of 40 years and its incidence increases progressively with age.

Chronic myeloid leukemia

The natural history of CML can be divided into two clearly distinguishable phases: the chronic or stable phase and the blastic phase.

Usually the chronic phase is well controlled with classical treatment (Busulfan), which causes satisfactory hematological and clinical remission in 80-85% of cases. This remission lasts an average of 36 to 46 months before evolving into an accelerated or blastic phase.

The onset of the blastic phase is usually preceded by a reappearance of general symptoms (fever, sweating, weight loss, uncontrollable splenomegaly, leukositosis) that does not respond to classical treatment, accompanied by anemia. It is possible to detect an increase in basophilic granulocytes in the peripheral blood.

The duration of this state is variable, between weeks and months. Then a number of blasts that generally exceed 20-30% appear in peripheral blood and bone marrow. Morphologically, in 70-80% of cases they have characteristics of myeloid or undifferentiated blasts that very rarely have Auer blastons; they are usually granular and with highly variable expression in myeloperoxidases (see Acute leukemias). In the remaining percentage, the morphology is lymphoblastic.

This last variant is related to a better therapeutic response.

CML can be considered as an invariably fatal disease that evolves from a stable phase to an acceleration or blast phase that generally does not respond to chemotherapy and is the cause of death.

Study methodology (Table 54-2)

History and physical examination

The natural history of CML can be divided into commonly in a young adult with asthenia, with two clearly distinguishable phases: the chronic or rexia and occasionally with a stable anemic syndrome and the blast phase, with fever and weight loss. The most notable clinical feature is the presence of a palpable base, moderate to large in size, in 70-80% of cases. Some patients may have bleeding in the form of purpura or "easy bleeding."

Peripheral blood test

The hematological findings that guide the diagnosis are:

1. Leukocytosis that is generally on the order of 200,000 / mm
2. There may be generally moderate anemia (9 g Hb%)
3. Platelets can be normal in number, decreased or exaggeratedly high
4. The leukocyte formula shows an absolute predominance of segmented neutrophils, myelocytes and up to 5-10% of myeloid blasts. 20% of patients are asymptomatic and the diagnosis is established by a routine blood count.

Extended bone marrow.

It shows a proliferation of myeloid elements in all maturational stages, which displace the cryropoietic and megakaryocytic sectors. There may be a variable degree of fibrosis at the time of diagnosis.

Leukocyte alkaline phosphatase . It is a leukocyte enzyme whose specific function is unknown. It usually increases with infections, stress, corticosteroid treatment, and Hodgkin's disease. The leukocytes of patients with CML have very low to undetectable levels cytochemically.

Vitamin B 12 . Levels are increased due to increased transcobalamin.

Uric acid . It is regularly elevated due to increased cell turnover.

Cytogenetic studies . Between 80% and 90% of patients with a clinical diagnosis of CML present a chromosomal marker in metaphases obtainable in bone marrow. It consists of the break (deletions) of the long arms of chromosome 22, whose genetic material is “relocated” (translocation) in the long arms of chromosome 9. This marker is called Philadelphia (Ph ') And in general it does not disappear with treatment . As the disease progresses, anomalies such as duplication of Ph 'isochromosome 17, tri-sornia of No. 8, and others are usually added.

Chronic lymphatic leukemia

Chronic lymphatic leukemia (CLL) is a disease characterized by a proliferation of morphologically mature lymphocytes, which gradually invade the peripheral blood. bone marrow. lymph nodes and spleen. Eventually the extralymphatic tissues can be affected.

Symptoms and signs

Skin . From 25 to 50% of cases may have skin infiltration at some point during their illness. The lesions can be mistaken for psoriasis or mycosis fungoides. and they range from macules to infiltrative nodular lesions.

Lymphadenopathy . Mediastinals are rare. In the abdomen, on the other hand, they are present in more than 90% of cases. The latter can cause obstruction of the bile duct, intestine or vessels (inferior vena cava syndrome).

Liver . Liver infiltration can cause cholestatic jaundice and organ enlargement.

Lungs . In advanced and late stages of the disease, up to 30% of cases may present with pulmonary infiltrates and / or pleural effusion. In addition, due to the immunological deficit, slow-resolution lobar pneumonias are frequent.

Susceptibility to infections . HypogammagIobulinemia, linked to a failure in the maturation of antibody-producing cells, predisposes to infections in the skin, airways, and genitourinary tract, abscess formation, and the development of herpes zoster and generalized reactions after vaccinations with live viruses.

Infections are sometimes aggravated by neutropenia.

The clinical disease may be preceded by a positive Coombs autoimmune hemolytic anemia. Much less frequently, it is associated with lupus erythematosus, rheumatoid arthritis, or Sjögren's syndrome.

Ritcher syndrome . This is the name given to the appearance of a massive retroperitoneal tumor with histiocytic or Hodgkin lymphoma and lymphocyte depletion, which occurs in approximately 5% of cases.

Study methodology

Interrogation and physical examination . CLL is a variable disease in its presentation. In 25% of cases the diagnosis is made accidentally in a routine blood count.

The most frequent is to find patients with mild anemia, adenopathy of moderate size and is-plenomegaly that generally does not exceed 5 cm below the costal margin.

Sometimes there are manifestations of bleeding (purpura, ecchymosis, hematomas related to thrombocytopenia). The onset of the disease can be determined by infections such as pneumonia or herpes zoster.

Peripheral blood study . The haematological study generally reveals an absolute lymphocytosis greater than 15,000 / mm3, finding counts that exceed IOO.OOO / m3 '. The leukocyte formula is made up almost entirely of mature lymphocytes. Anemia (when present) is normocytic-normochronic, and sometimes, when associated with a positive Coombs test, it is microspherocytic. Platelets may be normal or sometimes decreased.

Extended bone marrow . It shows a replacement of normal cellularity by mature lymphocytes, requiring for the diagnosis that they exceed 40-50% of cellularity.

Plasma proteins . 50% of the cases present hypogammaglobulinemia. There are between 1 and 5% of patients that have a monoclonal component in their serum.

Immunological studies . CLL is primarily a monoclonal B-cell disorder with immunoglobulins on its surface, recognizable as IgM and IgD. There are rare cases in which the disorder involves T cells and is recognized by ram erythrocyte rosettes.