If children need chemotherapy that will make their hair fall out, it's important to tell them that when they get to that point. If a mother is crying, I'll explain to the child that it's because she feels bad about the illness. Then hopefully the parent and child can talk to each other. Leukemia isn't something that you miss. There isn't any proof so far that diagnosing the disease early on makes a difference in overall prognosis.
Lymphocytic leukemia involves the lymphoid cells, and myelogenous involves the myeloid cells.
The B cells go through many stages of development and leukemia can occur at any one of these stages. The significance of all this is that you need different forms of treatment for the myeloid and lymphoid forms of the disease. Outcomes for myeloid forms of the disease have not been as favorable, but are getting better. Hodgkin's disease is a specific form of lymphoma. Both involve similar cells, and sometimes similar medications, although different combinations of drugs work better depending on the type of lymphoma.