Lymphomas and Lymphoid Neoplasms

Lymphoma Classification & Basics - Cellular Chaos Kickoff

• Lymphoma: Malignant lymphoid cell tumors, primarily in solid tissues (nodes, extranodal). Differentiated from leukemia (marrow/blood primary).
• WHO Classification: Based on:
  • Cell of origin (B, T, NK)
  • Morphology (cell/tissue appearance)
  • Immunophenotype (CD markers, e.g., CD20, CD3)
  • Genetics (translocations, mutations)
  • Clinical features (age, site, course)
• Clonality: Hallmark; neoplastic cells from a single progenitor.

⭐ Most Non-Hodgkin Lymphomas (NHLs), ~85-90%, are B-cell derived.

Hodgkin Lymphoma - Reed's Rogue Roster

• Key: Reed-Sternberg (RS) cells ("owl-eye"); classic are CD30+, CD15+.
• Clinical: Bimodal age (15-35 & >50 yrs), contiguous spread, "B" symptoms (fever, sweats, wt loss >10%).
• Classical HL (cHL) subtypes (RS cells CD30+, CD15+):
  • Nodular Sclerosis (NSHL): Most common; lacunar cells.
  • Mixed Cellularity (MCHL): EBV common; eosinophils.
  • Lymphocyte-Rich (LRCHL): Best prog.
  • Lymphocyte-Depleted (LDHL): Worst prog; HIV assoc.
• Nodular Lymphocyte Predominant HL (NLPHL):
  • "Popcorn" (L&H) cells: CD20+, CD45+, BCL6+; CD15-, CD30-. Indolent.
• 📌 Mnemonic (cHL RS): 15 x 2 = 30 (CD15+, CD30+).

⭐ Pel-Ebstein fever (cyclical fever) is rare but classic.

B-Cell NHLs - Antibody Army Uprising

⭐ CLL/SLL: Most common adult leukemia (West); CD5+, CD23+.

T-Cell & NK-Cell NHLs - T-Team Turmoil

• Mycosis Fungoides (MF) & Sézary Syndrome (SS):
  • Cutaneous T-cell lymphoma. MF: skin patches, plaques, tumors. SS: erythroderma, Sézary cells (>1000/µL blood).
  • Key: Pautrier's microabscesses (intraepidermal atypical T-cells); Sézary cells (cerebriform nuclei).
  • Immunophenotype: CD3+, CD4+, CD8-.
• Peripheral T-cell Lymphoma, NOS (PTCL-NOS):
  • Diagnosis of exclusion. Heterogeneous group, often aggressive.
• Anaplastic Large Cell Lymphoma (ALCL):
  • "Hallmark" cells (large, pleomorphic, horseshoe nuclei). CD30+.
  • ALK+ (t(2;5)): younger patients, better prognosis. ALK-: older patients, poorer prognosis.

  ⭐ ALK+ ALCL (t(2;5)) has better prognosis, common in younger patients.

• Extranodal NK/T-cell Lymphoma, Nasal Type:
  • Aggressive; midline facial destruction (nasal). Angiocentric.
  • Strong EBV association. Immunophenotype: CD3+, CD56+ (NK cell marker).

Lymphoma Diagnosis & Staging - Sleuth & Scale System

• Diagnosis:
  • Biopsy: Excisional (gold standard).
  • IHC, Flow cytometry: Lineage/markers.
  • Cytogenetics/Molecular (FISH, PCR): Key aberrations.
• Staging (Ann Arbor):
  • I: Single LN region.
  • II: ≥2 LN regions, same side diaphragm.
  • III: LN regions, both sides diaphragm.
  • IV: Widespread extralymphatic.
  • Modifiers: A/B (symptoms), E (extranodal), S (spleen), X (bulky >10cm).
• Imaging: PET-CT: Staging & response.
• Prognosis: IPI for NHL.

⭐ "B" symptoms in lymphoma staging include unexplained fever >38°C, drenching night sweats, and unexplained weight loss >10% in 6 months.

High‑Yield Points - ⚡ Biggest Takeaways

• Hodgkin Lymphoma: Characterized by Reed-Sternberg cells; typically CD15+, CD30+.
• Burkitt Lymphoma: "Starry sky" appearance; t(8;14) translocation involving c-myc.
• Follicular Lymphoma: Associated with t(14;18) (BCL2 gene); generally indolent course.
• Diffuse Large B-cell Lymphoma (DLBCL): Most common NHL in adults; aggressive clinical behavior.
• Mantle Cell Lymphoma: t(11;14) leading to Cyclin D1 overexpression; often poor prognosis.
• Multiple Myeloma: Neoplastic plasma cells, M-protein, CRAB criteria (Calcium, Renal, Anemia, Bone).
• CLL/SLL: Smudge cells on peripheral smear; CD5+, CD23+ B-cells.