Source / episode info
- **Episode:**82
- **Title:**Divine Intervention Episode 82 – USMLE Step 1 Hematology Review Part 4 (Oncology)
- **Published:**2019-02-25
- Source:Episode page
One-liner
This episode reviews key concepts in hematopathology, covering lymph node anatomy (paracortex/follicles), common metastatic patterns, and detailed comparisons of B-cell lymphomas (Burkitt's, Follicular, MCL) and leukemias (CLL, Hairy Cell), emphasizing specific translocations and immunophenotypes.
High-yield summary
- Lymph Node Architecture: In response to bacterial infection, the germinal follicles show follicular hyperplasia with well-demarcated architecture; this is distinct from a true lymphoma where the node architecture is effaced by neoplastic cells.
- Bimodal Age Distribution: Hodgkin Lymphoma (HL) classically presents in two peaks: young adulthood (15–34 years) and older age (>50 years).
- Translocation Signatures: Burkitt's Lymphoma involves t(8;14) leading to c-MYC overexpression. Follicular Lymphoma involves t(14;18) leading to BCL2 overexpression. Mantle Cell Lymphoma (MCL) involves t(11;14) leading to Cyclin D1 overexpression.
- Immunophenotype Differentiation: CLL is CD5+ and CD23+. MCL is CD5+ but lacks CD23 expression. T-cell lymphomas are typically positive for CD3, CD5, CD7.
- Clinical Pearls: The classic triad for Hairy Cell Leukemia includes massive splenomegaly, hepatosplenomegaly, and a "dry tap" on bone marrow aspiration.
- Metastatic Patterns: Left supraclavicular lymphadenopathy (varicose node) suggests abdominal/GI tract malignancy; right supraclavicular suggests lung or GI malignancy.
Learning objectives
- Differentiate between follicular hyperplasia and true lymphoma based on nodal architecture preservation.
- Identify the characteristic translocations (t(8;14), t(14;18), t(11;14)) associated with major B-cell lymphomas.
- Recognize the key clinical presentations and markers for CLL, MCL, and Hairy Cell Leukemia.
- Apply knowledge of lymph node drainage patterns to localize metastatic primary cancers (e.g., left vs right supraclavicular).
- Understand the difference between T-cell and B-cell lineage markers in lymphoma diagnosis.