What hematologic disorder is characterized by a decrease in all blood cell lines?

Pancytopenia is characterized by a decrease in the number of red blood cells, white blood cells, and platelets, resulting in a reduction across all blood cell lines. This condition can arise from various underlying causes such as bone marrow failure, autoimmune disorders, hypersplenism, or extensive infiltration of the bone marrow by malignancies or fibrosis.

The key distinguishing feature of pancytopenia is that it affects all three major cell types found in the blood, leading to symptoms related to the deficiencies of each, such as fatigue (due to anemia), increased susceptibility to infection (due to leukopenia), and increased bleeding or bruising (due to thrombocytopenia).

Other conditions mentioned do not present the same broad decrease across all cell lines. Thrombocytopenia, for example, specifically refers to a reduction in platelet count only. Leukemia primarily affects white blood cells, often leading to an increase in immature white blood cells rather than a decrease across all types. Anemia is characterized specifically by a decrease in red blood cells. Therefore, the comprehensive impact of pancytopenia on all blood components makes it the correct diagnosis for the described scenario.