Master Acute Lymphoblastic Leukemia (ALL) with Picmonic for Medicine

Acute lymphoblastic leukemia (ALL) is a neoplasm of immature B and T cells (pre B and pre T cells), which are referred to as lymphoblasts. About 85% of ALLs are B cell tumors and typically manifest in children less than 15 years of age. The less common T cell ALLs tend to present in adolescents as a thymic lymphoma in the mediastinum. In these cancers, the bone marrow is typically hypercellular and packed with lymphoblasts, which replace the normal elements within the bone marrow. Therefore, common symptoms include fatigue due to anemia and bleeding due to thrombocytopenia. Neoplastic infiltration of bone marrow can also cause bone pain from marrow expansion and infiltration of the subperiosteum. Immunostaining for terminal deoxynucleotidyl transferase (TdT), a specialized DNA polymerase that is expressed only in pre B and pre T lymphoblasts is positive in more than 95% of cases. Majority of these B-cell tumors also express the common acute lymphoblastic leukemia antigen (CALLA). Approximately 90% of ALLs demonstrate chromosomal changes, most commonly hyperploidy of chromosomes. These chromosomal aberrations are thought to cause the dysregulation of the expression and function of transcription factors that are required for normal B and T cell development. A fraction of B cell tumors contain a translocation of genes 12;21 involving the genes TEL and AML1, two genes required in very early hematopoiesis. This translocation is associated with better prognosis. This tumor is known to spread to the CNS and testes. With aggressive chemotherapy, about 95% of children with ALL obtain complete remission.