Haemoblastoses are a group of neoplastic diseases of the blood system arising from mutations in hematopoietic cells. They are based on tumor progression, leading to the loss of normal hematopoietic functions and the development of malignancy.
EtiologyMutation and oncogene expression in hematopoietic progenitor cells.
Core ProcessEscalation of malignancy via tumor progression.
Key SignSuppression of normal hematopoietic lineages and leukemization.
ComplicationsThrombocytopenia, hemorrhages, and therapy resistance.
Mechanisms of Development
Haemoblastoses are based on the genetic transformation of a normal hematopoietic cell. The key driver of this process is oncogene expression.
Further disease progression is driven by tumor progression—a process in which cells constantly change, adapting to the body's environment and therapy. This leads to:
Heterogeneity: the tumor becomes diverse and nonuniform.
Autonomy: cell growth ceases to depend on the body's regulatory signals.
Resistance: the tumor "escapes" the effects of cytotoxic agents.
Types of Atypia
Tumor progression inevitably leads to atypia—qualitative differences between tumor cells and normal cells:
Cellular atypia: manifested by changes in the morphology and structure of the blast cells themselves.
Tissue atypia: disruption of the proper ratio between tumor cells and stroma (characteristic of lymphomas).
Biochemical anaplasia: loss of specific biochemical properties inherent in healthy blood elements.
Functional Disorders
Haemoblastoses disrupt the function of both malignant and healthy blood cells. The main consequences include:
Immunodeficiency: decreased phagocytic activity of leukocytes and impaired immune response.
Anemic syndrome: impaired gas transport by erythrocytes.
Hemorrhagic syndrome: thrombocytopenia and dysfunction of blood coagulation factors, leading to hemorrhages.
Leukemization: release of immature blast cells into the peripheral bloodstream.
Mnemonic
P-A-R-A: Progression, Atypia, Resistance, Anaplasia. These four pillars describe the life cycle of any haemoblastosis.
Frequently asked questions
How are haemoblastoses classified by the localization of the primary tumor focus?
Based on the localization of the primary neoplastic transformation, haemoblastoses are classified into two main groups.
Leukemias — primary involvement of the bone marrow with mandatory changes in the peripheral blood.
Lymphomas — primary tumor growth outside the bone marrow (in lymph nodes or the lymphoid tissue of organs), where tumor cells do not initially circulate in the blood.
Into which groups are leukemias divided depending on the degree of tumor cell differentiation?
Depending on the degree of differentiation (maturity) of the tumor substrate, leukemias are divided into two main groups:
Feature
Acute Leukemias
Chronic Leukemias
Tumor Substrate
Immature, blast elements
Maturing (differentiating), cytoid elements
Clone Origin
Mutation of an early progenitor cell, early differentiation block
Mutation of a committed progenitor cell, differentiation partially preserved
This division reflects the level of malignancy and differentiation block, rather than the actual duration of the disease course.
What specific blood picture changes (leukocyte differential) are characteristic of acute leukemia?
Acute leukemia is characterized by a specific blood picture change known as the leukemic hiatus.
Leukemic hiatus (hiatus leukaemicus) — the presence of blast and mature forms of cells in the peripheral blood with a complete absence of intermediate (maturing) forms between them.
This phenomenon is considered pathognomonic for acute myeloid leukemia.
What specific genetic mechanisms and chromosomal abnormalities underlie haemoblastoses?
Haemoblastoses are based on the transformation of normal hematopoietic cells into tumor cells as a result of mutation and/or oncogene expression. Malignant transformation initially occurs in a single cell, followed by proliferation and expansion of the tumor clone.
Cellular mechanisms of malignant transformation include:
blockage of the ability to undergo apoptosis;
blockage of differentiation.
Chromosomal aberrations occur in all forms and are important for diagnosis and prognosis.
Specific chromosomal abnormalities and genetic markers include:
Philadelphia chromosome (Ph+) — translocation t(9;22)(q34;q11) resulting in the formation of the bcr/abl chimeric gene; characteristic of chronic myeloid leukemia.
In acute lymphoblastic leukemia, unfavorable prognostic factors include translocations t(9;22), t(1;19), and t(4;11).
In acute lymphoblastic leukemia, favorable prognostic factors are a DNA index > 1.16 and translocation t(12;21).
In acute myeloid leukemia, chromosomal aberrations in blasts are detected statistically more frequently.
What is leukemization?
It is the process by which immature tumor (blast) cells escape from the bone marrow into the peripheral blood, changing the leukemia form from aleukemic to leukemic.
Why does a tumor become resistant to treatment?
As a result of tumor progression, cells constantly mutate, increasing their adaptability and allowing them to "escape" the effects of chemotherapy.
What is the difference between cellular and tissue atypia?
Cellular atypia involves changes within the cell itself, whereas tissue atypia involves the disruption of structure and ratios between tumor cells and the surrounding stroma.
Go deeper
Detailed classification of leukemia forms
Mechanisms of normal hematopoiesis suppression
Comparative characteristics of lymphomas and leukemias
Biochemical markers of tumor anaplasia
Dynamics of bone marrow changes during progression