Lymphoblastic lymphoma in children — what parents need to understand

Lymphoblastic lymphoma is a fast-growing cancer of the lymphatic system in which immature white blood cells — called lymphoblasts — form a solid tumour in a lymph node or group of lymph nodes rather than multiplying primarily in the bone marrow. It belongs to the same family of diseases as acute lymphoblastic leukemia (ALL), and the two conditions share many biological features. In children, the most common presentation is a large mass in the chest (the mediastinum) arising from T-cell precursors, or swollen lymph nodes in the neck arising from B-cell precursors. Because the cancer grows quickly, evaluation and treatment need to begin promptly after diagnosis.

Lymphoblastic lymphoma and acute lymphoblastic leukemia (ALL) come from the same type of immature cell, but they differ in where the disease is most active. In lymphoblastic lymphoma, less than 25% of the bone marrow is replaced by lymphoblasts and the primary disease is in a solid lymph node mass or organ. When more than 25% of the marrow is involved, the condition is classified as ALL. This is an important distinction because treatment protocols differ slightly, and doctors make the call based on bone marrow biopsy results. In practice, many specialists treat lymphoblastic lymphoma using protocols very similar to ALL, because the biology and the cells involved are closely related.

The symptoms depend on where the tumour is. A chest (mediastinal) mass — the most common presentation — often causes a persistent dry cough, mild breathlessness during exercise, swelling of the face or neck (because the enlarged mass presses on a blood vessel called the superior vena cava), or difficulty swallowing. Lymph node disease in the neck, armpit, or groin shows up as painless lumps that grow over days to weeks. General symptoms that can appear with any lymphoma include unexplained fever lasting more than a few weeks, drenching night sweats, and weight loss without a clear reason. Any of these symptoms that appear quickly or together should be evaluated promptly by a doctor.

Diagnosis requires a biopsy — a sample of the tumour or affected lymph node — which is sent to a specialist pathologist. The sample is examined under the microscope and with advanced tests including immunohistochemistry (to identify the exact cell type), flow cytometry (to study the cell surface markers), cytogenetics (to look for chromosomal changes), and molecular testing. A bone marrow aspiration is also done to determine how much, if any, marrow is involved — this result helps classify the disease as lymphoma versus leukemia. Imaging (CT scan, PET-CT, or MRI) maps the extent of disease in the body. All these results together tell the team what subtype your child has and guide the treatment plan.

Treatment follows a structured multi-phase approach similar to ALL protocols. The first phase — induction — uses combination chemotherapy to achieve remission, typically within four to six weeks. The second phase — consolidation — intensifies treatment to eliminate any remaining cancer cells, including those that may have reached the fluid around the brain and spinal cord; intrathecal (spinal) chemotherapy is given as part of this phase. The third phase — maintenance — involves lower-intensity treatment continued over one to two years to prevent relapse. Radiation is used selectively in some cases. For children whose disease does not respond well to initial treatment or who relapse, a stem cell transplant may be considered. Every child treated at CION has their case reviewed by a multidisciplinary tumor board — no single doctor makes treatment decisions alone.

Most lumps in a child's neck are caused by reactive swollen lymph nodes from ordinary throat infections or colds, and they usually shrink within two to four weeks once the infection clears. Lymphoblastic lymphoma is far less common. However, you should see a doctor promptly if the lump is growing quickly (over days to weeks rather than staying the same size), if it is firm and painless, if it does not reduce after a course of antibiotics, if there are other lymph nodes swollen at the same time in other parts of the body, or if your child also has a fever, night sweats, or unexplained weight loss. A blood test and an ultrasound of the neck are usually the first steps the doctor will arrange, and they can rule in or out a number of conditions including lymphoma.