NCLEX Hematology Practice Test

Aplastic anemia is a bone marrow failure where the stem cells are destroyed or suppressed, so the marrow becomes hypocellular and is replaced by fat. On biopsy, you see very little hematopoietic tissue and increased adipose (fat) spaces. This lack of productive marrow explains the pancytopenia and the very low reticulocyte count seen in these patients.

In contrast, a hypercellular marrow with more hematopoietic cells would point to a condition with marrow overproduction or a reactive process, not to aplastic anemia. A normal cellularity marrow doesn’t fit the cytopenias, and erythroid hyperplasia would indicate increased red cell precursors, which again isn’t consistent with marrow failure.