8. Bone Marrow

Why do we perform a Bone Marrow (BM) study?

To evaluate hematopoiesis when peripheral blood findings are inconclusive.

What are some clinical indications for performing a BM?

Unexplained cytopenias, suspected leukemia or myeloma, staging for lymphomas, storage diseases, or systemic infections.

What does hematologic disease lead to?

Morphological abnormalities of peripheral blood cells.

How should bone marrow findings be interpreted?

Along with peripheral blood smear.

What is a minimal risk associated with a bone marrow biopsy?

It is a procedure that carries minimal risk with experienced hands and current needles.

What is the role of sinuses in bone marrow structure?

Sinuses are formed from several joining vessels and serve as areas where hematopoiesis occurs.

Where does hematopoiesis occur in the bone marrow?

In hematopoietic cords that lie outside the sinuses.

What is the average lifespan of a red blood cell (RBC)?

120 days.

What stages are involved in granulopoiesis?

Proliferating pool (myeloblasts, promyelocytes, myelocytes) and maturation storage pool (metamyelocytes, bands, segmented neutrophils).

What is the average lifespan of neutrophils in blood circulation?

6-10 hours.

How long does it take for megakaryocytes to produce platelets?

Approximately 5 days.

What are the two characteristics of marrow stem cells?

Self-renewal and multilineage differentiation.

What are hematogones?

Committed progenitor cells of lymphoid lineage.

In which conditions may hematogones be increased?

Neuroblastoma, iron deficiency anemia, idiopathic thrombocytopenic purpura (ITP).

What are colony stimulating factors (CSF’s)?

They influence the differentiation of progenitor cells in the bone marrow.

What influences erythropoiesis?

Erythropoietin.

What should be considered before performing a bone marrow procedure?

The procedure can be painful and should only be performed when indicated.

What are common indicators for bone marrow studies?

Anemia, polycythemia, leukocytosis, unexplained leukopenia, and presence of blasts.

Where is the most common site to obtain a BM sample?

Posterior iliac crest.

What is the purpose of the Jamshidi needle in a bone marrow procedure?

For performing the bone marrow aspiration and biopsy.

What is the two-part procedure for BM?

Aspiration for cell morphology and differential counts; biopsy for evaluating cellularity.

What is the first step in the BM aspiration procedure?

Preparing the site with antiseptic and local anesthetic.

How much marrow is typically drawn during aspiration?

1-1.5 ml of marrow.

What should the aspirated material be used for?

Preparing smears immediately.

What is important for preparing bone marrow smears?

Quality of smear depends on the lab tech's skill and speed.

What are touch imprints used for in BM sampling?

Cytomorphology and differential counts when aspirate smear is inadequate.

What staining technique is used for touch preparations?

Stained with Wright-Giemsa after fixing in absolute methanol.

What can be evaluated through core marrow biopsy?

Cellularity, architecture, and presence of granulomas or tumors.

What is the expected cellularity range for a 60-year-old patient?

30-50%.

What does an increased M:E ratio indicate?

Infection, chronic myeloid leukemia (CML), or erythroid hypoplasia.

What does a decreased M:E ratio suggest?

Erythroid hyperplasia (polycythemia) or myeloid suppression.

What is hemosiderin?

Storage iron in the bone marrow visualized as granules on Wright-Giemsa stained smears.

What does the Prussian Blue stain indicate in iron studies?

It is the gold standard for identifying iron stores and sideroblasts.

When is iron storage reported as absent?

When no stainable iron is detected.

What indicates sideroblasts' presence?

Aberrant rings around erythroblast nuclei.

What patient information is included in a Bone Marrow Report?

Patient data including age, clinical summary, and diagnosis.

What types of studies can samples from BM be processed for?

Histologic, flow cytometric, cytogenetic, microbiology, and molecular studies.

What are the rare sites for obtaining a BM sample?

Anterior iliac crest and spinal processes.

How should the patient be advised after the bm procedure?

To lie on the biopsy site for about 15-30 minutes.

What is a significant benefit of obtaining bone marrow samples?

They provide a large sample representing marrow in natural relationships.

What kind of surgical considerations must be taken in children during BM procedures?

Avoids sternum to prevent complications.

What is an aspiration artifact?

Hemorrhage into the biopsy site that complicates evaluation of cellularity.

What are the implications of cellularity on a differential count?

Marrow cellularity and M:E ratio are crucial for diagnosis.