✅ Model Answer: • Oral finding: Gingival hypertrophy with erythema, swelling, and bleeding – leukemic infiltration of the gums.
• Most suggestive of: Acute myelogenous leukemia (AML), particularly the monocytic subtype (FAB M4/M5).
• Key features: Swollen, boggy, erythematous, hypertrophied gums with spontaneous or easily induced bleeding.

✅ Model Answer: • Incidence: 10-20% of pediatric AML cases.
• Associated subtypes:
- FAB M4 (acute myelomonocytic leukemia).
- FAB M5 (acute monocytic leukemia).
- AML with 11q23 (KMT2A) rearrangements (e.g., t(9;11)).
- AML with monocytic differentiation (CD14+, CD64+).
• Gingival infiltration is a form of extramedullary leukemia (myeloid sarcoma/chloroma).

✅ Model Answer: • Clinical features of AML:
- Pancytopenia: Anemia (pallor, fatigue), neutropenia (fever, infections), thrombocytopenia (easy bruising, bleeding).
- Bone marrow failure: Pallor, fatigue, petechiae, epistaxis, gum bleeding.
- Extramedullary involvement: Gingival hypertrophy (swollen, bleeding gums), skin (leukemia cutis), orbit (chloroma/granulocytic sarcoma), CNS involvement (headache, cranial nerve palsies).
- Hepatosplenomegaly and lymphadenopathy.
- Fever: Often due to infection or the leukemia itself.
- Bone pain: Especially in long bones.
- Weight loss, anorexia.

✅ Model Answer: • Pathophysiology: Leukemic blasts with monocytic differentiation have a high affinity for tissues, especially the gingiva, skin, and other extramedullary sites.
• Monocytic blasts express adhesion molecules (e.g., CD11b, CD18) that facilitate infiltration into the gingival connective tissue.
• This leads to proliferation of leukemic cells in the gingival stroma, causing hypertrophy, swelling, and bleeding.
• The gingival involvement is a form of myeloid sarcoma (chloroma) – an extramedullary collection of immature myeloid cells.

✅ Model Answer: • Cytogenetic abnormalities in pediatric AML:
- Favorable risk: t(8;21)(q22;q22) (RUNX1-RUNX1T1), inv(16)(p13q22) (CBFB-MYH11), t(16;16).
- Intermediate risk: Normal karyotype, t(9;11)(p22;q23) (KMT2A-MLLT3).
- High risk (adverse): 11q23 rearrangements (other than t(9;11)), monosomy 7, monosomy 5, complex karyotype, FLT3-ITD (internal tandem duplication), KMT2A rearrangements.
- Other: NPM1 mutations (favorable in adults, variable in children), CEBPA mutations (favorable).
- Note: 11q23 rearrangements are more common in infants and are associated with extramedullary disease (gingival, skin, CNS).

✅ Model Answer: • Diagnostic workup:
- Complete blood count (CBC): Pancytopenia (anemia, neutropenia, thrombocytopenia), presence of blasts.
- Peripheral blood smear: Myeloblasts (Auer rods in some cases).
- Bone marrow aspiration and biopsy: Gold standard – ≥20% blasts. Morphology, cytochemistry (myeloperoxidase, Sudan black, non-specific esterase).
- Flow cytometry: Identifies myeloid/monocytic markers (CD13, CD33, CD14, CD64, CD117, CD34, HLA-DR).
- Cytogenetics and FISH: Identifies karyotypic abnormalities (11q23, t(8;21), inv(16), FLT3-ITD, NPM1).
- Molecular studies: KMT2A rearrangements, FLT3-ITD, NPM1, CEBPA.
- Lumbar puncture: For CNS involvement (cytospin).
- Imaging: CXR (mediastinal mass), echocardiogram (cardiac function before anthracyclines).

✅ Model Answer: • Treatment of pediatric AML:
- Induction chemotherapy: Standard "7+3" regimen – cytarabine (7 days) + anthracycline (3 days) – daunorubicin or idarubicin.
- Consolidation chemotherapy: High-dose cytarabine (HiDAC) ± additional agents.
- Allogeneic stem cell transplant (SCT): For high-risk features (11q23, FLT3-ITD, MRD+, complex karyotype, monosomy 7/5).
- Supportive care: Aggressive management of febrile neutropenia, tumor lysis syndrome prophylaxis (allopurinol/rasburicase), transfusion support (PRBCs, platelets), antifungal prophylaxis.
- Extramedullary disease: Systemic chemotherapy is primary treatment; local radiation may be used for orbital chloromas or CNS involvement.

✅ Model Answer: • Role of allogeneic SCT:
- Indications (high-risk AML):
- 11q23 (KMT2A) rearrangements (excluding t(9;11)).
- FLT3-ITD (especially high allelic ratio).
- Minimal residual disease (MRD) positive after induction/consolidation.
- Monosomy 7, monosomy 5, complex karyotype.
- Secondary AML.
- Relapsed AML (in second remission).
- Benefits: Graft-versus-leukemia effect, higher cure rates in high-risk groups.
- Risks: Graft-versus-host disease (GVHD), transplant-related mortality, infections.

✅ Model Answer: • Extramedullary manifestations of AML:
- Gingival infiltration: Swollen, bleeding gums (most common in monocytic AML).
- Leukemia cutis: Skin nodules, papules, or plaques; often violaceous.
- Chloroma (myeloid sarcoma): Solid tumor of immature myeloid cells; can occur in orbit, skin, bone, soft tissue, CNS.
- Orbital involvement: Proptosis, periorbital swelling (especially in infants).
- CNS involvement: Meningeal leukemia (headache, vomiting, cranial nerve palsies).
- Lymphadenopathy and hepatosplenomegaly.
- Mediastinal mass (rare in AML, more common in T-ALL).

✅ Model Answer: • AML:
- More extramedullary involvement (gingival hypertrophy, skin, orbit, chloroma).
- Bone marrow failure (anemia, neutropenia, thrombocytopenia) is prominent.
- Auer rods on peripheral smear.
- Age: More common in infants and older children (bimodal).
- Myeloid markers on flow cytometry (CD13, CD33, CD117).
- Associated with 11q23 rearrangements, FLT3-ITD.
• ALL:
- More common in children (peak age 2-5 years).
- Bone pain, lymphadenopathy, hepatosplenomegaly are more prominent.
- Extramedullary: CNS (meningeal) is more common than gingival.
- Lymphoblastic markers (CD19, CD10, CD20, TdT).
- Associated with hyperdiploidy, ETV6-RUNX1, BCR-ABL.

✅ Model Answer: • Flow cytometry role:
- Identifies myeloid lineage: Expression of CD13, CD33, CD117, CD34, HLA-DR.
- Monocytic differentiation: CD14, CD64, CD11b, CD4 (dim).
- Distinguishes AML from ALL: Lacks lymphoid markers (CD19, CD10, TdT).
- Subtype classification: Helps differentiate FAB subtypes (M0-M7) based on marker expression.
- Detection of minimal residual disease (MRD): Follows treatment response using leukemia-associated immunophenotypes.
- Rapid and sensitive: Results within hours.

✅ Model Answer: • Differential diagnoses:
- Leukemia (AML/ALL): Gingival infiltration with pancytopenia, fever, and other systemic signs.
- Gingivitis/periodontitis: Localized inflammation, usually no systemic symptoms, no pancytopenia.
- Drug-induced gingival hyperplasia: Phenytoin, cyclosporine, nifedipine (calcium channel blockers) – history of medication use.
- Scurvy (vitamin C deficiency): Swollen, bleeding gums, perifollicular hemorrhages, poor wound healing.
- Gingival fibromatosis: Hereditary or idiopathic, slow-growing, no systemic signs.
- Granulomatosis with polyangiitis (Wegener's): Strawberry gingivitis, but rare in children; associated with respiratory and renal involvement.
- Neurofibromatosis type 1: Gingival enlargement (rare).

✅ Model Answer: • "Your child has been diagnosed with acute myelogenous leukemia (AML), a type of blood cancer that affects the bone marrow and blood cells."
• "The swollen, bleeding gums are a sign of leukemic cells infiltrating the gum tissue – this is a common feature of this type of leukemia."
• "We will start intensive chemotherapy to destroy the leukemic cells and achieve remission. Treatment typically involves several cycles of chemotherapy and may include a stem cell transplant if high-risk features are present."
• "During treatment, your child may experience side effects like low blood counts, infections, and bleeding. We will support them with transfusions, antibiotics, and close monitoring."
• "The treatment is intensive, but the cure rate for AML in children has improved significantly. We are here to support you and your child throughout this journey."
• "We will also arrange genetic testing to determine the subtype and guide treatment decisions."

✅ Model Answer: • Prognosis: Has improved significantly with modern chemotherapy and supportive care.
- Overall survival (OS): ~60-70% for pediatric AML.
- Event-free survival (EFS): ~50-60%.
- Prognostic factors:
- Favorable: t(8;21), inv(16) – excellent prognosis (~90% survival).
- Intermediate: Normal karyotype, t(9;11) – moderate prognosis.
- Adverse: 11q23 (other than t(9;11)), FLT3-ITD, monosomy 7/5, complex karyotype – poor prognosis, higher relapse risk.
- Infants: Higher incidence of 11q23 rearrangements, often lower survival.
- Minimal residual disease (MRD): MRD positivity after induction is an independent predictor of relapse.
- Stem cell transplant: Improves survival in high-risk patients.

✅ Model Answer: • Supportive care role:
- Transfusion support: Packed red blood cells for anemia, platelets for thrombocytopenia.
- Infections: Empiric antibiotics for febrile neutropenia; antifungal prophylaxis (fluconazole, caspofungin); antiviral prophylaxis (acyclovir).
- Tumor lysis syndrome prophylaxis: Hydration, allopurinol (or rasburicase for high-risk).
- Nutritional support: Maintain adequate nutrition, consider TPN if needed.
- Pain management.
- Dental hygiene: Gentle oral care (soft toothbrush, saline rinses) to minimize gum bleeding and infection.
- Psychological support: For the child and family.
- Fever management.