Bone Marrow Failure Workup

Bone marrow failure can present as isolated cytopenias such as pure red cell aplasia or amegakaryocytic thrombocytopenia; or with pancytopenia, as in aplastic anemia.

Peripheral blood findings

Anemia is common, with red cells usually demonstrating normal morphology, though occasionally patients can present with macrocytic mean corpuscular volumes (MCVs) accompanied by inappropriately low reticulocyte counts (usually is less than 1%0, indicating a lack of red cell production. 

Platelet counts are lower than normal, with a paucity of platelets in the blood smear. Platelet size is normal, but a low platelet count may cause greater heterogeneity in size.

Agranulocytosis (ie, a decrease in all granular white blood cells, including neutrophils, eosinophils, and basophils) and a decrease in monocytes are observed. A relative lymphocytosis occurs (ie, increased percentage) without an increase in numbers.

Ham test

The Ham test, or sucrose hemolysis test, result may be positive in a patient with underlying paroxysmal nocturnal hemoglobinuria, but a recent transfusion with packed red blood cells may induce a false-negative test result (ie, because the normal transfused red cells are tested). Folate, vitamin B12, and serum erythropoietin levels usually are increased.

Fanconi anemia screening

The diagnosis of Fanconi anemia should be considered in all children and young adults presenting with any of the following:

• Hypoplastic or aplastic anemia ^[10] or other cytopenias
• Unexplained macrocytosis
• Myelodysplastic syndrome
• Acute myelogenous leukemia
• Epithelial malignancies
• Subtle, but characteristic, physical anomalies

The criterion standard screening test for Fanconi anemia is based on the characteristic hypersensitivity of Fanconi anemia cells to DNA crosslinking agents (eg, mitomycin C, diepoxy butane [DEB], cisplatin) and involves exposing a culture of replicative cells (ie, phytohemagglutinin [PHA]–stimulated peripheral blood lymphocytes or skin fibroblasts) to low doses of mitomycin C or DEB and then examining the cells in metaphase for evidence of chromosomal breaks and radial chromosomes.

Identification of gene mutations

Mutated genes can be identified by retroviral complement studies, by direct sequencing or by denaturing high-performance liquid chromatography (DHLP).

Dyskeratosis congenita screening

Screening for dyskeratosis congenita should be considered in children and adults who have:

1. Bone marrow failure, acute myelogenous leukemia, or myelodysplastic syndrome
2. Negative mitomycin C and DEB test results (which would rule out Fanconi anemia) and either
3. Hypopigmented macules, reticulated hypopigmentation, dystrophic nails, or oral leukoplakia or
4. Evidence in their family history, obtained via genomic deoxyribonucleic acid (DNA) screening, of X-linked or autosomal dominant forms of dyskeratosis congenita (DKC1-3)

Diamond-Blackfan anemia and Shwachman-Diamond syndrome characteristics

Diamond-Blackfan anemia is a pure red cell aplasia that usually manifests in early infancy. Shwachman-Diamond syndrome is a syndrome of bone marrow failure (classically neutropenia), exocrine pancreatic insufficiency, and metaphyseal dysostosis that also manifests in early childhood.

Histologic findings

A bone marrow biopsy is the definitive method to diagnose bone marrow failure and can reveal the status of each precursor cell line, as follows:

• Pure red cell aplasia characteristically affects erythroid progenitor cells.
• Amegakaryocytic thrombocytopenia is evidenced by a lack of megakaryocytes.
• The presence of hypoplastic bone marrow differentiates aplastic anemia from aleukemic leukemia; the latter results in the production of blast cells in the marrow. ^[11]

Bone marrow activity can be measured by radiographic methods. Ferrokinetic studies have been conducted using a radioactive label, such as iron-59 or indium-111, both of which are taken up by erythroid cells. Radioactive iron is no longer available in the United States.

Magnetic resonance imaging (MRI) can be used to differentiate bone marrow fat cells from hematopoietic cells, based on the differences in their densities and intensity signals.

Positron emission tomography (PET) scanning with radiolabeled oxygen can measure the metabolic activity difference between hypoplastic marrow and cellular marrow.

A bone marrow aspirate and biopsy should be performed to assess the cellularity and morphology of the residual cells. In general, the marrow is replaced with fat cells and stromal cells are replaced with lymphocytes, with very few hematopoietic cells. Occasionally, localized pockets of marrow are present (ie, from a sampling error), which can be misleading. To evaluate cellularity, the core biopsy specimen should be at least 1 cm long.

Residual erythroid cells may show evidence of dysplasia with nuclear-cytoplasmic maturation dissociation (commonly described, in the absence of a folate or vitamin B12 deficiency, as megaloblastoid features).