Bone Marrow Flashcards
Hematopoiesis
Myeloid stem cell —> RBC, granulocytes, monocytes, platelets
Lymphopoiesis
Lymphoid stem cell —> T cell, B cell, plasma cell
Erythropoiesis
Erythropoietin (from kidney) regulates RBC production
Hypoxia (or ILs, CSFs, hormones) —> Epo release
Granulopoiesis
Myeloid series production (granulocytic + Monocytic cells)
Inflammatory mediators (ILs, TNFa) —> cytokine (G-CSF, GM-CSF) production —> stimulate granulopoiesis + monocytopoiesis
Megakaryopoiesis
Thrombopoietin (Tpo) by liver regulates thrombopoiesis (constitutively produced)
Megakaryocytes —> endomitosis to become polyploid —> extend into bone marrow venous sinusoids —> fragment to platelets
Cytology
Identification of cell types within tissue or fluid by evaluation of smears made from specimen
Faster than biopsy, more detail of internal cell structures
Sacrifices anatomic relationship
Core biopsy
Histologic assessment
Definitive determination of cellularity and fibrosis
Within the environment of tissue
Dynamic nature of bone marrow
Peripheral demands for WBC/RBC/platelets —> shift in bone marrow cytologies profiles due to hyperplastic responses
Disease of bone marrow —> impacts peripheral leukocyte, erythrocyte, platelet numbers
Reasons to evaluate bone marrow
Unexplained/persistent dec or inc in particular cell line
Abnormal or immature cells in circulation
Atypical cell reactions
FUO
Unexplained lab findings - hypercalcemia, hyperglobulinemia
Staging of neoplasia - lymphoma or mast cell tumors
NEED CONCURRENT CBC
Indications for core biopsy
Bone changes
Abnormal bone marrow cellularity (hypo/hyper cellular, aplasia)
Focal lesions
Unsuccessful aspiration
Parameters to evaluate in bone marrow
Cellularity + particles
Maturation sequences + morphology
Frequency of lymphocytes, macs, plasma cells, other cells
Adequacy of iron
Presence of abnormal cells
MYELOID:ERYTHROID ratio (M:E)!!
Erythroid series
Rubriblast —> prorubricyte —> rubricyte —> metarubricyte —> polychromatophil —> RBC
Myeloid series
Progranulocyte —> myelocyte —> metamyelocyte —> band cell —> neutrophil, eosinophils, basophil
Hyperplasia
Increase in response to peripheral demand for specific cell type
PREDICTIBLE
Causes of erythroid hyperplasia
Hemorrhage (trauma, coagulopathies, neoplasia)
Hemolysis (IMHA, toxin, infectious, oxidant injury, enzyme deficiencies, hypophosphatemia)
Trigger for erythropoiesis
Low Hb —> hypoxemia —> Epo by kidneys —> erythropoiesis in marrow
Clinical indication of erythroid hyperplasia
M:E decreases, immature RBC in blood (polychromatophilic RBC - bluish cells, and reticulocytes in blood)
Response to acute severe hemolysis or hemorrhage
Abrupt decrease in hemoglobin —> immediate tissue oxygen compromise —> tissue necrosis —> concurrent myeloid hyperplasia —> peripheral leukocytosis
M:E may be normal with increase in both myeloid + erythroid line
CONCURRENT CBC required for M:E evaluation
Myeloid hyperplasia
Response to increased need for granulocytes and/or monocytes (i.e. infection)
M:E increases
Immature cells in blood increase with “left shift” in maturation
Megakaryocytic hyperplasia
In response to destruction, loss consumption of platelets
(Immune mediated disease, DIC)
Bone marrow hypoplasia
Hypoplasia of a cell line results in peripheral decrease in that cell type
Clinical signs reflect missing cell type
Causes of bone marrow hypoplasia
Anemia of chronic disease / inflammation
Immune-mediated
Cytotoxic or drug-induced
Infection (viral)
Endocrine-induced
Iron deficiency
Renal failure
Malnutrition
Inherited disorders
Idiopathic
Anemia of chronic disease or inflammation
Bone marrow hypoplasia
Most common cause of non regenerative anemia
Not as predictible as hyperplasia
Types of bone marrow inflammation
Acute myelitis
Granulomatous or pyogranulomatous
Myelodysplastic Syndrome
Group of Clonal myeloid proliferative disorders
Abnormal cell morphology
Marrow profile indicates hyperplasia of one or more cell line without improvement in peripheral cell count
Can be associated with FeLV, FIV
Leukemia
Malignant hematopoietic neoplasm originating in bone marrow
OFten significant number of neoplastic cells in blood
Lymphocytic or myelogenous, acute or chronic
Myelogenous leukemia
AML: peripheral blood smear with blast cells, lack of appropriate maturation of marrow cells, most common in FeLV cats; poor prognosis
CML: high peripheral cell count, normal morphology (process of elimination diagnosis); rare, chronic,
Lymphoid leukemia
ALL: immature lymphocytes, may efface marrow, young to middle aged
CLL: well-differentiated lymphocytes, usually do not efface marrow, usually older animals
Multiple myeloma
Plasma cell neoplasm in marrow, malignant
Myelofibrosis
Generally secondary (scar formation, GF-induced fibroblast proliferation)
Difficult to aspirate
Histologic diagnosis
