• Leukemoid reactions

    Leukemoid reactions - pathological changes in blood composition, similar to the picture of blood in leukemia. To cause leukemoid reactions, viruses, tissue helminth toxins, blood cell decay products( in hemolysis) and tumors, sepsis, etc. can occur. This leads to hyperplasia of the hematopoietic cells with normal ratios of individual elements in the red bone marrow.

    Leukemoid reactions can be single, double and triple, myeloid, eosinophilic, lymphoid, monocytic, and symptomatic erythrocytosis.

    ■ Leukemoid reactions of the myeloid type are characterized by a pattern of peripheral blood resembling chronic myelogenous leukemia. This is the most frequent type of leukemoid reactions. The development of this type of reactions can result in infections( sepsis, scarlet fever, erysipelas, pyoinflammatory processes, diphtheria, pneumonia, tuberculosis), ionizing radiation, shock, exogenous and endogenous intoxications( sulfanilamide preparations, GC, uremia, carbon monoxide poisoning), lymphogranulomatosis, metastasis of a malignant tumor into the bone marrow, acute hemolysis, acute blood loss. In the peripheral blood, moderate leukocytosis with a subleukemic shift in the leukocyte formula is revealed, with toxic granularity and degenerative changes in neutrophilic granulocytes. The number of platelets is within the norm. Myelogram is characterized by an increase in the content of young cells of the neutrophilic series, with the predominance of more mature elements( myelocytes, metamyelocytes).In chronic myelogenous leukemia, unlike leukemoid reactions, a sharp increase in the cellularity of the bone marrow is revealed with an increase in the leucoerythroblastic ratio and an increase in the number of megakaryocytes. Eosinophil-basophilic association, often observed in chronic myelogenous leukemia, is absent in the leukemoid reaction.

    ■ Leukemoid reactions of the eosinophil type. The causes of this type of reaction are mostly helminthiases - trichinosis, fascioliasis, opisthorchiasis, strongyloidiasis, migration of the larvae of ascarids, amebiasis, etc. More rarely, leukemoid reactions of the eosinophil type are observed in collagenoses, allergies of unclear etiology, lymphogranulomatosis, immunodeficiency states, endocrinopathies. In peripheral blood, leukocytosis is detected up to 40-50x109 / l with high eosinophilia( 60-90%) due to mature forms of eosinophils. The bone marrow examination allows differentiating this type of reaction with the eosinophilic version of chronic myeloid leukemia and with acute eosinophilic leukemia. Bone marrow punctate in the leukemoid reaction is characterized by the presence of more eosinophilic cells, more mature than in leukemia, and the absence of blast cells pathognomonic for leukemia.

    ■ Leukemoid reactions of lymphatic and monocytic type.

    □ Infectious mononucleosis is an acute viral disease, which is based on hyperplasia of the reticular tissue, manifested by changes in blood, reactive lymphadenitis and enlarged spleen. In peripheral blood, increasing leukocytosis to 10-30x109 / l due to the increase in the number of lymphocytes and monocytes. The content of lymphocytes reaches 50-70%, monocytes - 10-40%.In addition to these cells, plasma cells, atypical mononuclears, pathognomonic for this disease can appear. In the period of convalescence, eosinophilia occurs. The number of erythrocytes and the level of Hb is usually within the norm and decreases only with infectious mononucleosis complicated by autoimmune hemolytic anemia. In the punctate bone marrow against the background of normal cellularity, a slight increase in the content of

    of monocytes, lymphocytes, plasma cells is revealed, 10% of them are atypical mononuclears.

    □ Symptomatic infectious lymphocytosis is an acute benign epidemic disease that occurs with lymphocytosis primarily in children in the first 10 years of life. The causative agent of the disease is an enterovirus from the Coxsackie group of the 12th type. In peripheral blood - pronounced leukocytosis to 30-100x109 / l due to the increase in the amount of content to 70-80%.In 30% of cases, eosinophils( 6-10%) are detected, polysegmentation of neutrophil granulocyte nuclei. In the myelogram, lymphoid metaplasia is absent. Symptomatic lymphocytosis can also be a symptom of infectious diseases such as typhoid fever, paratyphoid, brucellosis, visceral leishmaniasis, etc.

    □ Cat scratch disease is an acute infectious disease( the causative agent is Rochalimaea henselae), which occurs after a cat bite or scratch. At the beginning of the disease in peripheral blood, leukopenia is noted, which in the period of severe clinical manifestations is replaced by moderate leukocytosis - up to 12-16x109 / l with a shift to the left. Individual patients may have lymphocytosis up to 45-60%, the appearance of lymphoid elements resembling atypical mononuclears in infectious mononucleosis. Necessity in the study of red bone marrow usually does not arise.