Bone marrow disorders Flashcards
How frequent are bone marrox disorders in cats
Bone marrow disorders are not common in cats
What is myelophtisis
This is a consequence of particular bone marrow diseases rather than a disease entity in itself
Myelophtisis refers to a condition in which the hematopoietic components are crowded out of the bone marrow cavity by an infiltrative disease such as myelofibrosis, leukemia, lymphoma or other neoplastic processes
- as a consequence, the displaced cells are forced to undergo extra-medullary hematopoiesis (for example in the liver or spleen)
What is a myelodysplastic syndrome
A myelodysplastic syndrome is characterized by maturation defects and abnormal development in one or more cell lines
- the bone marrow appears hypercellular on cytological evaluation
- however as hematopoiesis is ineffective, peripheral cytopenias are common
- and the cells that are produced may fail to function properly
What condition can follow a myelodysplastic syndrome
The myelodisplastic syndrome is often a prelude to full-blown leukemia and may be associated with persistent FeLV infection
What are the two types of myelodisplastic syndrome predominantly seen in cats
Myelodisplastic syndrome is classified into six separate types in human medicine, and two of these types are predominantely seen in cats:
- refractory cytopenias with multi-lineage dysplasia (RCMD)
- refractory anemia with excess blasts (RAEB)
What are the key features for refractory cytopenias with multi-lineage dysplasia (RCMD)
Affected cats tend to have moderate to severe macrocytic, normochromic, non-regenerative anemia, often with excessive nucleated RBCs
These cases can also have auto-agglutination
Many have concurrent thrombocytopenia and leucopenia
The prognosis is generally guarded, however some cats may respond to prednisolone +/- cytarabine or vincristine
What are the key features for refractory anemia with excess blasts (RAEB)
These cats have bi- or pancytopenia (including moderate to severe non-regenerative anemia, with increased nRBC +/- autoagglutination) with dysplasia seen in all cell lines and myeloblasts on bone marrow examination
This disease has been observed in both FeLV-positive cats (median age 3 years) and FeLV-negative cats (median age 9 years)
The prognosis for this condition is grave with most cats progressing to acute myeloid leukemia
What are the key features for aplastic anemia
Bone marrow examination is characterized by depletion of hematopoietic cells and replacement with fatty tissue
Causes:
- Infectious: FPV, FeLV, histoplasmosis, toxoplasmosis
- Drugs: chemotherapeutics, albendazole, griseofulvin (especially FIV-positive cats), chloramphenicol
- Idiopathic
Prognosis depends on the inciting cause
Treatement generally consists of providing transfusion and prevention/treatment of secondary infections until the bone marrow can recover
What are the key features of myelofibrosis
Myelofibrosis is characterised by the proliferation of the stromal elements (i.e., fibroblasts, extracellular collagen) within the bone marrow, which ultimately leads to the destruction of the normal hematopoietic structures
Causes:
- Idiopathic
- chronic IMHA
- bone marrow necrosis
- leukemia/other neoplasia
- myelodysplasia
The prognosis is guarded and dependent on the underlying cause
How frequent is primary bone marrow neoplasia (i.e., leukemia) frequent nowadays
Given the decline in prevalence of FeLV infection, feline leukemia is uncommon
What are the key features for acute leukemias
Predominantly manifest with:
- marked peripheral cytopenia
- increased numbers of immature blast forms on bone marrow cytology
Tend to have an aggressive clinical course
What are the key features of chronic leukemias (also known as myeloproliferative neoplasia)
Cells tend to have relatively normal morphology
Tend to have increased numbers of a particular cell type in the peripheral blood (+/- concurrent mild decreases in other cell lines)
Tend to have a more indolent clinical course
Which neoplastic conditions can involve the bone marrow (i.e. neoplastic infiltration)
The following conditions may involve the bone marrow:
- multiple myeloma
- lymphoma
- malignant histiocytosis
- mast cell tumors
