The B symptoms, such as fever, night sweats, and weight loss, are often present as well.Central nervous system (CNS) symptoms such as cranial neuropathies due to meningeal infiltration are identified in less than 10% of adults and less than 5% of children, particularly mature B-cell ALL (Burkitt leukemia) at presentation.The signs and symptoms of ALL are variable and include:
Generalized weakness and feeling tired
Anemia
Dizziness
Headache, vomiting, lethargy, neck stiffness, or cranial nerve palsies (CNS involvement)
Frequent or unexplained fever and infection
Weight loss and/or loss of appetite
Excessive and unexplained bruising
Bone pain, joint pain (caused by the spread of "blast" cells to the surface of the bone or into the joint from the marrow cavity)
Breathlessness
Enlarged lymph nodes, liver, and/or spleen
Pitting edema (swelling) in the lower limbs and/or abdomen
Petechiae, which are tiny red spots or lines in the skin due to low platelet levels
Testicular enlargement
Mediastinal mass

Cause
The cancerous cell in ALL is the lymphoblast. Normal lymphoblasts develop into mature, infection-fighting B-cells or T-cells, also called lymphocytes. Signals in the body control the number of lymphocytes so neither too few nor too many are made. In ALL, both the normal development of some lymphocytes and the control over the number of lymphoid cells become defective.ALL emerges when a single lymphoblast gains many mutations to genes that affect blood cell development and proliferation. In childhood ALL, this process begins at conception with the inheritance of some of these genes. These genes, in turn, increase the risk that more mutations will occur in developing lymphoid cells. Certain genetic syndromes, like Down Syndrome, have the same effect.
Age at diagnosis: children 1–10 years of age are most likely to develop ALL and to be cured of it. Cases in older people are more likely to result from chromosomal abnormalities (e.g., the Philadelphia chromosome) that make treatment more difficult and prognoses poorer. Older people are also likely to have co-morbid medical conditions that make it even more difficult to tolerate ALL treatment. White blood cell count at diagnosis of greater than 30,000 (B-ALL) or 100,000 (T-ALL) is associated with worse outcomes
Cancer spreading into the Central nervous system (brain or spinal cord) has worse outcomes. Morphological, immunological, and genetic subtypes
Persons response to initial treatment and longer length of time required (greater than 4 weeks) to reach complete remission
Early relapse of ALL
Minimal residual disease
Genetic disorders, such as Down syndrome, and other chromosomal abnormalities (aneuploidy and translocations)Cytogenetics, the study of characteristic large changes in the chromosomes of cancer cells, is an important predictor of outcome. Some cytogenetic subtypes have a worse prognosis than others. These include:
Person with t(9,22) positive-ALL (30% of adult ALL cases) and other Bcr-abl-rearranged leukemias are more likely to have a poor prognosis, but survival rates may rise with treatment consisting of chemotherapy and Bcr-abl tyrosine kinase inhibitors. A translocation between chromosomes 4 and 11 occurs in about 4% of cases and is most common in infants under 12 months.Hyperdiploidy (>50 chromosomes) and t(12;21) are good prognostic factors and also makeup 50% of pediatric ALL cases.Unclassified ALL is considered to have an intermediate prognosis risk, somewhere in-between the good and poor risk categories.