Mechanisms of development
Hemoblastoses are based on the genetic transformation of a normal hematopoietic cell. The key driver of this process is the expression of oncogenes.
The further development of the disease is determined by tumor progression—a process in which cells constantly mutate, adapting to the body's conditions and therapy. This leads to:
- Heterogeneity: the tumor becomes inhomogeneous.
- Autonomy: cell growth ceases to depend on the body's regulatory signals.
- Resistance: the tumor "escapes" the effects of cytostatics.
Types of atypia
Tumor progression inevitably leads to the formation of atypia—qualitative differences between tumor cells and normal ones:
- Cellular atypia: manifests as changes in the morphology and structure of the blast cells themselves.
- Tissue atypia: disruption of the correct ratio between tumor cells and stroma (characteristic of lymphomas).
- Biochemical anaplasia: loss of specific biochemical properties inherent in healthy blood elements by cells.
Functional disorders
Hemoblastoses disrupt the function of not only tumor cells, but also healthy blood cells. The main consequences include:
- Immunodeficiency: decreased phagocytic activity of leukocytes and immune response failures.
- Anemic syndrome: impaired gas transport by erythrocytes.
- Hemorrhagic syndrome: thrombocytopenia and coagulation factor dysfunction, leading to hemorrhages.
- Leukemization: release of immature blast cells into the peripheral bloodstream.
Briefly: answers to topical questions
How are hemoblastoses classified according to the localization of the primary tumor focus?
Based on the localization of the primary tumor transformation, hemoblastoses are classified into two main groups.
- Leukemias—primary bone marrow involvement with mandatory changes in the peripheral blood.
- Lymphomas—primary tumor growth outside the bone marrow (in lymph nodes or lymphoid tissue of organs), where tumor cells do not initially circulate in the blood.
What groups are leukemias divided into depending on the degree of differentiation of tumor cells?
Depending on the degree of differentiation (maturity) of the tumor substrate, leukemias are divided into two main groups:
| Sign | Acute leukemias | Chronic leukemias |
|---|---|---|
| Tumor substrate | Immature, blast elements | Maturing (differentiating), cytic elements |
| Clone origin | Mutation of an early progenitor cell, differentiation block at an early stage | 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 changes in the blood picture (leukocyte formula) are characteristic of acute leukemia?
Acute leukemia is characterized by a specific blood picture change called a leukemic hiatus.
- Leukemic hiatus (hiatus leukaemicus)—the presence of blast and mature cell forms in the peripheral blood with the complete absence of intermediate (maturing) forms between them.
In sources, this phenomenon is indicated as pathognomonic for acute myeloblastic leukemia.
What specific genetic mechanisms and chromosomal abnormalities underlie hemoblastoses?
Hemoblastoses 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 malignancy include:
- blocking the ability to undergo apoptosis;
- blocking differentiation.
Chromosomal aberrations occur in all forms and are important for diagnosis and prognosis.
Specific chromosomal abnormalities and genetic markers indicated in the sources:
- Philadelphia chromosome (Ph+)—translocation t(9;22)(q34;q11) with the formation of the bcr/abl chimeric gene; characteristic of chronic myeloid leukemia.
- In acute lymphoblastic leukemia, unfavorable prognostic factors include t(9;22), t(1;19), and t(4;11) translocations.
- In acute lymphoblastic leukemia, favorable prognostic factors are a DNA index greater than 1.16 and the t(12;21) translocation.
- In acute myeloid leukemia, chromosomal aberrations in blasts are detected statistically more often.
P-A-R-P: Progression, Atypia, Resistance, Anaplasia. These four pillars describe the life cycle of any hemoblastosis.
Class and exam questions
What is leukemization?
This is the process of immature tumor (blast) cells exiting the bone marrow into the peripheral blood, changing the form of leukemia from aleukemic to leukemic.
Why does a tumor become resistant to treatment?
As a result of tumor progression, cells constantly mutate, which increases their adaptability and allows them to "escape" the effects of chemotherapy.
What is the difference between cellular and tissue atypia?
Cellular atypia concerns changes inside the cell itself, while tissue atypia concerns the disruption of structure and the ratio between tumor cells and the surrounding stroma.
What else to study on this topic
- Detailed classification of leukemia forms
- Mechanisms of normal hematopoiesis lineage suppression
- Comparative characteristics of lymphomas and leukemias
- Biochemical markers of tumor anaplasia
- Dynamics of bone marrow changes during progression
Master the entire topic in the "Pathophysiology" course
This is a summary. The course covers everything tested in classes and exams.
- Full study guide on "Hemoblastoses" and 4,913 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 135 video lessons on the subject
Other topics in "Chapter 21. Typical Pathology Forms of the Blood System"
Free video lessons: pathophysiologyShort lessons with lecture notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.