Oncology: Leukemia, Lymphoma, and Solid Tumors
Leukemia
Acute lymphoblastic leukemia is the most common childhood malignancy; presentation includes pallor, bruising, bone pain, and lymphadenopathy. Risk stratification uses age, white count, cytogenetics, and minimal residual disease after induction. Central nervous system prophylaxis is mandatory because the CNS is a sanctuary site. Acute myeloid leukemia, particularly acute promyelocytic leukemia with t(15;17) PML-RARA, is a hematologic emergency: start all-trans retinoic acid on suspicion, before genetic confirmation, because early death from disseminated intravascular coagulation is preventable.
Lymphoma and solid tumors
Hodgkin lymphoma presents with painless cervical adenopathy and a mediastinal mass that can obstruct the airway. Burkitt lymphoma grows fast and is highly curable but causes dramatic tumor lysis. Neuroblastoma secretes catecholamines and can produce opsoclonus-myoclonus; Wilms tumor presents as an abdominal mass and metastasizes to lung. Osteosarcoma arises near the knee and spreads to lungs; Ewing sarcoma favors the diaphysis. Retinoblastoma presents with leukocoria.
Emergencies
Tumor lysis syndrome - hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia - is managed with vigorous hydration, rasburicase (contraindicated in G6PD deficiency), and close monitoring. Febrile neutropenia requires empiric anti-pseudomonal antibiotics within an hour. Hyperleukocytosis with leukostasis needs cytoreduction. Spinal cord compression and superior vena cava syndrome need urgent steroids and oncology involvement.
Rule of thumb
For any new mediastinal mass, avoid general anesthesia until imaging and tissue are obtained, because supine positioning can precipitate airway collapse.
Trap
Do not delay all-trans retinoic acid for a lumbar puncture or for confirmation of the translocation in a child with suspected acute promyelocytic leukemia and coagulopathy.