Aplastic. Marrow biopsy. Fat cells are the clear ovoid or circular spaces and compose about three-quarters of the area of this section. Most of the remaining area is a clear pink matrix. No megakaryocytes are evident. Hematopoietic cells are profoundly decreased in number. In the aplastic marrow most of the cells are lymphocytes and occasional plasma cells. Rarely, “hot spots” are seen in aplastic marrow. These are very infrequent areas of residual hematopoietic cells.
Aplastic. Marrow biopsy. (A) Lower power view. Absence of marrow hematopoietic cells between bone trabeculae, characteristic of severe aplasia, as might be seen after irradiation or other profound marrow injury. Marrow totally replaced by fat cells. (B) Higher power view. Total replacement of hematopoietic marrow by fat cells. Each space represents fat dissolved during preparation. Contrast to V.A.001 in which some residual lymphocytes and plasma cells are present characteristic of autoimmune (autoreactive T cell-induced) aplastic anemia.
Aplastic Anemia. Marrow Biopsies. (A) Normal marrow, moderately hypercellular, but normal for this patient’s age, 15 years. (B) Normal marrow, Normocellular for patient’s age, 60 years. (C) Aplastic marrow, markedly hypocellular. In the latter situation lymphocytes and plasma cells are the principal residual cellular component.
Aplastic Anemia. Marrow Biopsy. Aplastic marrow, markedly hypocellular. Note two plasma cells and two lymphocytes that compose the principal residual cellular component.
Hypercellular. Marrow biopsy. Fat cells are absent. The marrow parenchyma is composed of 100% hematopoietic cells. The giant cells with pinkish cytoplasm are megakaryocytes. Several are transected at the level of the nuclei, the darker blue centrally placed structures. The very dark nuclei with scant cytoplasm are erythroblasts. The paler staining slightly larger cells with nuclei are developing neutrophils. Scattered cells with intensely reddish-orange cytoplasm are eosinophils. This magnification is best used for determining cellularity and megakaryocyte prevalence, a general impression of the erythroid to myeloid ratio, and in pathological states the presence of abnormal cells.
Hypocellular. Marrow biopsy. Fat cells are the clear ovoid or circular spaces and compose about two-thirds of the area of this section. The giant cells with pinkish cytoplasm are megakaryocytes. Two are transected at the level of the nuclei, the darker blue centrally placed structures. The very dark nuclei with scant cytoplasm are ...