This chapter contains notes on bone marrow (strictly relevant to hematology). This document is an excellent companion to the chapter on hematopoiesis available in my store. Topics include but are not limited to bone marrow composition, function, relevant bone marrow laboratory procedures, stem cell...
Bone marrow, as discussed is the hematopoiesis section, plays an integral
role in the production, maturation, and maintenance of blood cells. It can
also be a good indicator of blood-related disorders and diseases.
Colony-stimulating factors influence stem cell differentiation within
the bone marrow
CSFs are produced from certain ells after exposure to monocyte
interleukin (IL-1) and tissue necrosis factor (TNF)
BONE MARROW STRUCTURE AND COMPONENTS
Artery enters bone and branches to the periphery area called
sinuses
Several sinuses join to make a collecting sinus
This becomes a central vein that returns into systemic circulation
Hematopoiesis occurs in hematopoietic cords
Cords lie outside the sinuses
After maturation, cells cross the walls of sinuses to enter circulation
BONE MARROW IRON STORES
Storage of iron in bone marrow is hemosiderin
Has higher content than ferritin
Appears as brownish bluish granules on Wright-Giemsa-stained
smears
Prussian Blue stain used to be more precise
Hemosiderin and some ferritin granules are seen as bright blue
specks
o Hgb iron and dispersed ferritin do not stain
REPORTING IRON STORES
When no stainable iron is detected on the bone marrow smear or
tissue it indicates iron storage depletion or absence
This may be reported as:
o Absent
o Decreased
o Adequate
o Moderately increased
o Markedly increased
Also can be reported numerically from 0-4 with 2 being normal
In children, iron mainly stores as ferritin and does not stain with
Prussian Blue
, Some derangements in iron metabolism result in aberrant ringing
around erythroblast nuclei-termed side oblasts
STEM CELLS IN BONE MARROW
2 characteristics
o Self-renewal
o Multilineage differentiation
Can be further subcategorized
o Pluripotent: gives rise to many different cell lines
o Committed (progenitor): dedicated to one lineage and cannot
self-renew
Marrow stem cells are morphologically indistinguishable from small
lymphocytes
bone marrow and thymus are primary lymphoid organs of antigen-
independent progenitor lymphoid cell proliferation
HEMATOGONES
Committed to progenitor cells of lymphoid lineage
Increased in normal infants, older children, and sometimes in adults
May be increased in:
o neuroblastoma
o iron deficiency anemia
o idiopathic thrombocytopenic purpura (ITP)
Resemble lymphoblastic leukemia
Be aware of the conditions in which they occur
HEMATOLOGIC DISEASES
Morphological abnormalities of peripheral blood cells
Bone marrow should be interpreted alone with a peripheral smear
Experienced hands and current needles should perform a biopsy,
which minimizes risks
INDICATIONS FOR BONE MARROW STUDIES
Biopsies of bone marrow are expensive and painful. It’s important to know
when it is indicated that the patient could benefit from the diagnostic results
of bone marrow analysis. Hematologic diseases affecting primarily the bone
marrow and causing an increase/decrease in any cellular blood element (or
more than one in the case of leukemias) are the basis for performing a bone
marrow biopsy.
Examples:
Anemia
Polycythemia
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