Essence of the pathological process
The disease is based on a marked suppression of hematopoiesis in the bone marrow. The main issue lies in the impaired proliferation and differentiation of hematopoietic stem cells. Due to the inhibition of these processes, profound pancytopenia develops in the peripheral blood.
Clinical manifestations
Patients face severe clinical manifestations caused by blood cell deficiency:
- Severe hypoxemic syndrome due to a lack of erythrocytes.
- Hemorrhagic syndrome manifested by an increased tendency to bleeding.
- Secondary immunodeficiency leading to frequent infectious complications.
At the same time, it is important to remember that splenomegaly is not characteristic of this disease.
Laboratory and morphological findings
Key changes are detected upon examination of the blood and bone marrow:
- Bone marrow trephine biopsy: hematopoietic tissue is massively replaced by adipose tissue, with only small islands of myeloid tissue remaining.
- Peripheral blood: erythrocytes remain normocytic or macrocytic, as well as normochromic, but reticulocytes are completely absent.
Differential diagnosis and specific variants
The disease must be differentiated from a number of other conditions, including preleukemic states and myelodysplastic syndrome (MDS).
Particular attention is drawn to myelophthisic anaemia, which clinically resembles aplastic anaemia. It occurs against the background of myelofibrosis, granulomatous diseases, or tumor metastasis to the bone marrow.
Among specific variants, pure red cell aplasia is distinguished, which is more commonly diagnosed in adults and is often associated with a benign thymoma.
Briefly: answers to topical questions
Deficiency of which specific peripheral blood cells causes the development of hemorrhagic syndrome in aplastic anaemia?
The development of hemorrhagic syndrome in aplastic anaemia is associated with a deficiency of platelets in the peripheral blood — thrombocytopenia. In the total form of aplastic anaemia, thrombocytopenia of 60–30 × 10⁹/L and hemorrhagic syndrome are described; a platelet count below 100.0 × 10⁹/L is also a diagnostic criterion for aplastic anaemia. Bone marrow examination in aplastic anaemia shows the absence or disappearance of megakaryocytes.
A decrease in the count of which cells leads to the development of secondary immunodeficiency in aplastic anaemia?
The development of secondary immunodeficiency and infectious complications in aplastic anaemia is associated with a decrease in white blood cells, primarily neutrophils and granulocytes. Peripheral blood tests reveal leukopenia with profound neutropenia, as well as marked granulocytopenia (granulocyte levels drop below 2.0 × 10⁹/L). It is the deficiency of these cells that predisposes patients to severe infections.
What exogenous factors (chemical, physical, infectious) can cause acquired aplastic anaemia?
Acquired aplastic anaemia can be caused by the following exogenous factors:
- Physical factors — ionizing radiation, X-rays.
- Chemical factors and medications — benzene, cytostatics, immunosuppressants, sulfonamides, chloramphenicol, phenylbutazone, gold preparations, cimetidine, meprobamate, chlorpromazine.
- Infectious factors — hepatitis virus, infectious mononucleosis virus, herpes, tuberculosis.
What hereditary (congenital) forms of aplastic anaemia exist?
Hereditary (congenital) forms of aplastic anaemia include the following variants:
- Fanconi anaemia — a total form that is often combined with skeletal malformations or congenital heart defects.
- Estren-Dameshek anaemia — a familial hypoplastic anaemia presenting as a total form with the development of pancytopenia.
- Diamond-Blackfan anaemia — a congenital pure red cell hypoplastic anaemia characterized by a deficiency of erythroid cells only.
What cellular composition changes are detected in the myelogram during sternal puncture in patients with aplastic anaemia?
The myelogram obtained from bone marrow puncture in patients with aplastic anaemia reveals a sharp decrease in the number of all nucleated cells. A characteristic diagnostic sign is a general decrease in bone marrow cellularity. In addition, the cytological preparation shows the complete disappearance (absence) of megakaryocytes. In total forms of the disease, these changes reflect the suppression of all hematopoietic lineages and the development of profound pancytopenia.
Aplastic anaemia = A-plasia (no stem cell growth) + Fat instead of marrow + Zero reticulocytes + Spleen not enlarged.
Class and exam questions
What happens to the bone marrow in aplastic anemia?
A dramatic suppression of hematopoiesis occurs. Trephine biopsy reveals that active hematopoietic tissue is replaced by adipose tissue, with only isolated islands of myeloid cells remaining.
What changes are found in the peripheral blood?
Profound pancytopenia develops. Erythrocytes may be normocytic or macrocytic, normochromic, but a characteristic feature is the complete absence of reticulocytes.
Which pathology clinically resembles aplastic anaemia?
Myelophthisic anaemia, which develops in granulomatous diseases, myelofibrosis, or replacement of the bone marrow by tumor metastases.
What else to study on this topic
- Pathogenesis of hematopoietic stem cell proliferation impairment
- Differential diagnosis with myelodysplastic syndrome
- Features of myelophthisic anaemia and its causes
- Association of pure red cell aplasia with thymoma
- Causes and mechanisms of development of hemorrhagic syndrome and secondary immunodeficiency
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