Classification of hemoblastoses
Depending on the primary site of tumor growth, two main types are distinguished:
- Leukemias (leukemia): primary lesions of the bone marrow. The tumor substrate is formed by stem or pluripotent cells that have undergone malignant transformation directly within the bone marrow tissue.
- Lymphomas: monoclonal tumors arising from lymphatic cells at various stages of differentiation. They develop both before and after contact with the central organs of lymphopoiesis (the thymus, lymph nodes, or spleen).
Morphological features and dissemination
A key characteristic of leukemias is the ability of tumor cells to disseminate hematogenously. The process of organ involvement typically occurs in two stages:
- Primary stage: involvement of hematopoietic organs (spleen, liver, lymph nodes).
- Secondary stage: involvement of other tissues and organs of the body.
Microscopically, this manifests as the formation of leukemic infiltrates. They are located in the interstitium, surrounding blood vessels and penetrating their walls. Such diffuse infiltration inevitably leads to the destruction of the functional parenchyma of the affected organ.
Briefly: answers to topical questions
Which organs are considered central organs of lymphopoiesis in the context of lymphoma development?
In the context of lymphoma development, the central organs of lymphopoiesis include the thymus, lymph nodes, and spleen.
Lymphomas arise before or after contact of a malignant lymphatic cell of varying levels of differentiation with these organs. Meanwhile, in the general scheme of immunogenesis, the central (primary) lymphoid organs where antigen-independent differentiation occurs include:
- Thymus — ensures the maturation of T lymphocytes.
- Bone marrow — ensures the development of B lymphocytes and natural killer (NK) cells.
Leukemia — "bone marrow" (internal), Lymphoma — "lymph nodes" (external).
Class and exam questions
What is the main difference between leukemia and lymphoma?
Leukemia primarily affects the bone marrow, whereas lymphomas develop from lymphatic cells in lymphoid organs.
Why does organ parenchyma undergo necrosis in leukemias?
Due to the formation of diffuse leukemic infiltrates around blood vessels, which disrupt tissue structure and blood supply.
Which organs are primarily affected in leukemias?
Hematopoietic organs are affected first: the spleen, liver, and lymph nodes.
What else to study on this topic
- Cytogenetic basis of stem cell transformation
- Differential diagnosis of leukemia types
- Stages of lymphoma development depending on contact with the thymus
- Comparative characteristics of diffuse and focal infiltration
- Impact of cell differentiation grade on disease prognosis
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