Leukaemia in children: Viva

This is a branching oral built to probe the reasoning that holds the risk stratification and the resuscitation-before-diagnosis at the centre, and to expose the candidate who has memorised the headline without the corners. The questions escalate from the framing to the stabilisation, the diagnosis, the risk assignment, and the definitive therapy, with deliberate probes into the pitfalls. [1]

Opening question: framing the problem

The examiner opens with the film and the count and asks how you frame this problem in a single sentence, and what your first priority is. [9]

A strong answer names acute leukaemia with the circulating lymphoblasts, and states that the first priority is the resuscitation of the dangerous elements, the anaemia, the bleeding risk, the neutropenic fever, and the tumour lysis risk. [7]

Model answer. This child has a trilineage cytopenia with circulating lymphoblasts, which is acute lymphoblastic leukaemia until proven otherwise. My first priority is to resuscitate the dangerous elements, and then to confirm the diagnosis with an urgent bone marrow aspirate and trephine biopsy in a specialist centre. [1]

Probe one: the resuscitation

The examiner presses for exactly what you do in the first four hours, and why you choose those blood products. [7]

A strong answer reproduces the three legs. Red cells are transfused for the symptomatic anaemia, given slowly, and all the cellular products are irradiated and leucodepleted to prevent the transfusion-associated graft-versus-host disease. Platelets are held for a count under ten times ten to the nine per litre in the stable child and under twenty in the febrile or the bleeding child. Tumour lysis is prevented with the hyperhydration using an isotonic fluid without potassium, the rasburicase for the high-risk child, and the four-to-six-hourly biochemistry. The febrile neutropenia gets an empiric antipseudomonal beta-lactam within one hour after the blood cultures. [3][7]

Pitfall probe. Why must you check the glucose-6-phosphate dehydrogenase status before the rasburicase? Because the rasburicase causes the severe haemolysis and the methaemoglobinaemia in the deficiency, and the allopurinol is used where the status is unknown in the at-risk child. [3]

Probe two: the diagnostic pathway and the risk assignment

The examiner asks how you confirm the diagnosis, what ancillary studies you send on the marrow, and how you assign the risk group. [1]

A strong answer describes the bone marrow aspirate and the trephine biopsy at the posterior iliac crest, with the aspirate providing the cells for the morphology, the flow cytometry to define the B-cell lineage by the CD19 and CD10, and the cytogenetics and the molecular panel that drive the risk stratification. The standard risk is the age of one to under ten years with a white cell count under fifty times ten to the nine per litre, and this boy qualifies by the clinical criteria. The favourable genetics are the ETV6-RUNX1 and the high hyperdiploidy, and the minimal residual disease at the end of the induction has the final word on the intensity. [1]

Pitfall probe. What would a mediastinal mass on the chest film tell you instead? It would raise the T-cell acute lymphoblastic leukaemia, the classic anterior mediastinal mass of the older boy, and it would convert any procedure into an airway-first emergency, with no sedation before the airway is secured. [7]

Branch one: the Down syndrome neonate

The examiner pivots to a two-week-old with the Down syndrome and a white cell count of sixty with the circulating blasts, and asks what this is and what its natural history is. [6]

A strong answer names the transient myeloproliferative disorder, driven by a truncating GATA1 mutation, affecting roughly one in ten neonates with the trisomy twenty-one, resolving spontaneously in most, but carrying the risk of the hepatic fibrosis in the minority and of the acute megakaryoblastic leukaemia in roughly ten to twenty percent of the survivors within the first few years. Every affected neonate enters a surveillance programme, and the pitfall is to over-treat the transient disorder or to lapse the surveillance and miss the later leukaemia. [6]

Branch two: the Philadelphia positive disease

The examiner pivots to an older child whose marrow shows the BCR-ABL1 fusion, and asks how the treatment changes. [10]

A strong answer states that the Philadelphia chromosome positive ALL, once uniformly fatal, is now treated with the tyrosine kinase inhibitor, the imatinib or the dasatinib, added to the standard chemotherapy backbone, and continued through the maintenance. The survival has risen into the range of the other high-risk leukaemias, and the stem cell transplant is reserved for the refractory disease. [1][10]

Branch three: the relapse

The examiner pivots to a child two years into the maintenance who develops the marrow relapse, and asks how the relapsed ALL is managed. [10]

A strong answer names the relapse as the commonest cause of the death from the childhood cancer, with the marrow, the central nervous system and the testis as the sanctuary sites. The treatment rests on the re-induction, the risk stratification, the stem cell transplant for the high-risk relapse, and the contemporary immunotherapies, the blinatumomab and the chimeric antigen receptor T-cell therapy, which have transformed the relapsed B-cell disease. [10]

Closing question: counselling the family

The examiner closes with the diagnosis confirmed, and asks how you counsel the family. [1]

A strong answer describes the honest and hopeful conversation that names the diagnosis, explains that it is the commonest childhood cancer, that the contemporary survival exceeds ninety percent on the modern protocols, and that the treatment runs over two to three years through the phases of the induction, the consolidation and the maintenance. The family is introduced to the multidisciplinary team, given a written plan, taught the neutropenic precautions and the fever emergency, and supported by the social work and the educational liaison. [1]