Lymphomas originate from cells in the body’s lymph nodes and mainly manifest as painful, growing and palpable lumps that are attached to the underlying tissue. There are two main types of this cancer, Hodgkin’s lymphoma and non-Hodgkin’s lymphoma, and many subtypes. Lymphomas are the third most common type of childhood tumors after leukemia and brain tumors and are seen in areas where lymph nodes are mostly located, such as the head and neck, armpits, around the heart and abdominal cavity. Although the location and spread of lymph node cancer can be monitored with tests such as computed tomography and MRI, PET scan is especially important in evaluating both the extent and treatment response. Lymphomas are primarily treated with chemotherapy, but depending on the course of the disease, targeted molecular therapy and autologous or allogeneic stem cell transplants may be used for treatment.