100+ Free Cert Medical Oncology(SA) Paed Practice Questions

Explanation: The t(12;21)(p13;q22) translocation generates the ETV6-RUNX1 (formerly TEL-AML1) fusion gene. Present in approximately 22-25% of childhood precursor B-ALL cases, it is associated with cryptic translocation detectable by FISH or RT-PCR and portends an excellent (favorable) event-free and overall survival under modern risk-adapted therapy.

Explanation: T-cell acute lymphoblastic leukaemia (T-ALL) characteristically presents in older children/adolescents (predominantly males) with hyperleukocytosis, a large anterior mediastinal mass, pleural/pericardial effusions, and high risk of superior vena cava (SVC) syndrome and acute airway compression.

Explanation: In pediatric ALL protocols (COG, BFM, NOPHO), end-induction MRD negativity is defined as < 0.01% (< 10^-4, or fewer than 1 leukemic blast per 10,000 nucleated cells). Patients achieving < 0.01% MRD at end-induction have significantly higher event-free survival and lower relapse rates.

Explanation: Infant ALL (< 12 months of age) is a biologically distinct entity characterized by high rate of KMT2A (formerly MLL) gene rearrangements located on chromosome 11q23 (most commonly t(4;11) KMT2A-AFF1). It typically presents with high WBC, hepatosplenomegaly, CNS involvement, and a pro-B CD10-negative immunophenotype with poor event-free survival.

Explanation: Burkitt lymphoma is a highly aggressive mature B-cell non-Hodgkin lymphoma characterized by t(8;14)(q24;q32) in ~85% of cases (or variant translocations t(2;8) or t(8;22)), leading to constitutive overexpression of the MYC proto-oncogene under the control of immunoglobulin gene enhancers. Histology demonstrates the classic 'starry-sky' appearance.

Explanation: Standard first-line therapy for pediatric APML (driven by the t(15;17)(q22;q21) PML-RARA fusion) is the chemo-free targeted combination of All-trans retinoic acid (ATRA) and Arsenic trioxide (ATO). This combination induces differentiation and degradation of the PML-RARA fusion protein, achieving cure rates >95% while dramatically reducing chemotherapy toxicities.

Explanation: Transient Myeloproliferative Disorder (TMD), or transient leukaemia, occurs in ~10% of neonates with Down syndrome. It is caused by acquired somatic mutations in exon 2 of the erythroid/megakaryocytic transcription factor gene GATA1. Most cases undergo spontaneous regression within 1-3 months, though ~20-30% subsequently develop myeloid leukaemia of Down syndrome (ML-DS / AMKL) within 4 years.

Explanation: Nodular sclerosis classic Hodgkin lymphoma (NScHL) accounts for approximately 70-80% of Hodgkin lymphoma cases in adolescents and young adults. Histology shows collagen bands encapsulating nodular aggregates of lymphocytes, plasma cells, eosinophils, and lacunar Reed-Sternberg variants expressing CD15 and CD30.

Explanation: ALK-positive Anaplastic Large Cell Lymphoma (ALCL) is characterized in >80% of cases by the t(2;5)(p23;q35) translocation, which fuses the Nucleophosmin (NPM1) gene to the Anaplastic Lymphoma Kinase (ALK) gene, leading to constitutive ALK tyrosine kinase activation.

Explanation: Blinatumomab is a bispecific T-cell engager (BiTE) antibody construct that simultaneously binds CD19 on precursor B-lymphoblasts and CD3 on cytotoxic T-cells, triggering T-cell activation and blast lysis. Massive systemic T-cell activation releases proinflammatory cytokines (IL-6, IFN-gamma, TNF-alpha), causing Cytokine Release Syndrome (CRS), treated with Tocilizumab (anti-IL-6 receptor antibody) and supportive care.