What is acute lymphoblastic leukemia (ALL)? Acute lymphoblastic leukemia (ALL) is a malignant clonal disease that originates from lymphocytes. The incidence rate is about 2.7/100,000, and the peak incidence of ALL is in childhood (0-9 years old), which can account for more than 70% of childhood leukemias and about 20% of adult leukemias. Clinical manifestations of acute lymphocytic leukemia (ALL): ALL has a rapid onset and the clinical manifestations are related to the proliferation and infiltration of leukemic cells. There are four major clinical manifestations as follows: anemia: more than 80% of patients are anemic at the onset; fever and infection: infection sites are common in the oral cavity, gums, lungs, skin and soft tissues, perianal area, etc.; bleeding: bleeding is a common manifestation, with skin and mucous membrane bleeding being the most common; organ tissue infiltration: it can manifest as lymph node enlargement, testicular leukemia, etc. Acute lymphoblastic leukemia (ALL) diagnosis, typing? The diagnosis of ALL is currently based on cytomorphological, immunological, cytogenetic and molecular biology (MICM) diagnostic models. The latest WHO classification criteria for acute leukemia considers a bone marrow smear with a percentage of primitive/naive lymphocytes ≥ 20% to be diagnostic. Different subtypes can be diagnosed and classified according to different differentiation antigens on the surface of leukemic cells using immunological techniques. They are generally classified into T and B cell lineages. How is acute lymphoblastic leukemia (ALL) treated? Treatment of childhood ALL is more effective, with a 5-year event-free survival rate of 80%. Adult ALL treatment has learned from the successful experience of childhood ALL, and the efficacy has also improved significantly, with a complete remission rate of up to 70% or more with initial treatment, and a possible cure expected for about 30% of patients. 1.Induction of remission: Induction of remission is the use of chemotherapeutic drugs to minimize leukemia cells after disease diagnosis to achieve complete remission. 2.Consolidation and intensive treatment: After complete remission, there are still residual leukemia cells of different degrees, and further consolidation and intensive treatment with chemotherapeutic drugs are needed. 3.Maintenance therapy: It is an integral part of treatment after complete remission, and good results have been achieved in children with ALL. 4.Hematopoietic stem cell transplantation: Allogeneic hematopoietic stem cell transplantation is recommended for patients with suitable donors in adults, especially those with high risk factors. 5.Central nervous system: Early prevention of central nervous system is emphasized in any type of ALL, mainly by intrathecal injection of chemotherapeutic drugs.