Pediatric Hematology and Oncology
What to master
Know anemia classification by MCV (microcytic, normocytic, macrocytic) and the common causes at each age. Master iron deficiency-the most common nutritional anemia-and its stages (depleted stores, iron-deficient erythropoiesis, frank anemia). Understand hemoglobinopathies: sickle cell disease (vaso-occlusive crises, acute chest syndrome, splenic sequestration, aplastic crisis) and thalassemia (microcytic, target cells, iron overload with transfusions). Know bleeding disorders: hemophilia A/B (X-linked, prolonged PTT) versus von Willebrand disease (mucocutaneous bleeding, prolonged PTT and bleeding time). Understand leukemia presentation (pallor, bruising, bone pain, hepatosplenomegaly) and lymphoma differences (Hodgkin vs non-Hodgkin).
Concepts that recur
Neutropenic fever is an emergency-start broad-spectrum antibiotics immediately after cultures. Tumor lysis syndrome causes hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia. Splenic sequestration in sickle cell disease causes sudden anemia and shock-treat with transfusion. Aplastic crisis is usually parvovirus B19. Know transfusion reactions and iron overload monitoring.
Traps
Examiners test microcytic anemia differential-iron deficiency versus thalassemia trait; the Mentzer index and iron studies help. Another trap is assuming a normal platelet count excludes bleeding disorder-coagulation factor defects have normal platelets. Beware sickle cell pain crisis management: hydration, analgesia, oxygen if hypoxic, and look for triggers.
Rule of thumb
Fever in a neutropenic child is a medical emergency: cultures then empiric antibiotics within an hour. For microcytic anemia, check ferritin and hemoglobin electrophoresis before treating.