Hemogram and bone marrow morphology in children with chronic aplastic anemia and myelodysplastic syndrome

Aplastic anemia (AA) and myelodysplastic syndrome (MDS) are both acquired disorders in which bone marrow fails to produce or release sufficient blood cells. Anemia, infections and thrombocytopenia are common signs of such diseases. Clinically, it is difficult to distinguish chronic aplastic anemia (CAA) from MDS, especially from MDS without splenomegaly. As prognosis and treatment of AA and MDS are different, it is extremely important to make a differential diagnosis for the two diseases.

The medical records of 31 patients with CAA and 17 patients with MDS were retrospectively reviewed. Hemogram, bone marrow smear and biopsy for those patients were analyzed.

The mean counts of monocytes and platelets in the peripheral blood of the CAA patients were significantly lower than those of the MDS patients. Bone marrow smear showed a reduction of cellularity in CAA patients. The mean counts of myeloblasts+promyelocytes, myeloblasts+proerythroblasts, and megakaryocytes in the bone marrow of CAA patients were markedly lower than those in MDS patients. But the mean lymphocyte count was reversed. Bone marrow cells showed morphological abnormalities in MDS. Hematopoietic tissue in the bone marrow biopsy decreased obviously in more than 96% of the patients with CAA. Adipose tissue in the bone marrow of CAA patients increased obviously. A reduction or deficiency (<2 cell/piece) of megakaryocytes was noted in 28 patients with CAA. Fibrous tissue in the bone marrow was detected in 5 patients with CAA. Bone marrow biopsy results showed hypercellular changes in 12 MDS patients. Ten patients showed aggregated erythroblasts which were in the same stage of development, and 15 patients had abnormal localization of immature precursors (ALIP).

Blood cell counts can be decreased in addition to the reduction of cellularity in the bone marrow without dyshematopoiesis in CAA patients. Peripheral blood monocytes, fibrous tissue and cellularity in bone marrow are increased in MDS. Dyshematopoiesis and ALIP may appear characteristically in the children with MDS. Histology of bone marrow is important in the differential diagnosis of MDS and CAA.