XIV. Hodgkin's Lymphoma

• A. Less common than NHL; approximately 10,000 cases per year
• B. Incidence with respect to age bimodal, with one peak in late adolescence, young adulthood, second peak in sixth decade
  • 1. This bimodal curve shifts to younger ages in undeveloped countries
• C. Unlike nonHodgkin's lymphomas, diagnosed by the presence of a minor cellular component, the Reed Sternberg cell, found in the appropriate microscopic cellular background
• D. Classification of Hodgkin's lymphoma has also been recently revised
  

• E. Classification:
  
  
  
• F. Are characteristic patterns of involvement, and characteristic variants of Reed Sternberg cell associated with different subtypes
  • 1. Lymphocyte predominant
    • a. Usually presents with limited disease in the neck of young adults
    • b. Associated with L and H (lymphocytic and histiocytic) cell (popcorn cell) variant RS RS cell
  • 2. Nodular sclerosis
    • a. Usually presents in the anterior mediastinum and neck of young adult females
    • b. Associated with lacunar variant Reed Sternberg cell
  • 3 Lymphocyte depleted
    • a Often presents in retroperitoneum
    • b Accompanied by sclerosis and pleomorphic RS cell variants
• G. As in NHL, there are ancillary immunologic studies that can assist the dx of Hodgkins' lymphoma, and distinguish from immunoblast reaction or unusual variants of NHL
  • 1. Expression of CD15 and CD30 antigens in golgi and on cell membrane by immunohistochemistry.
• H. Hodgkin's lymphoma spreads contiguously via lymphatics
• I. Staging as in NHL- may or may not include laparotomy/splenectomy
• J. Therapy
  • 1. Hodgkins lymphoma is a curable malignancy
  • 2. Overall cure rate approximately 80%
  • 3. With modern therapy, prognosis based more on staging, bulk of disease, than morphologic subtype. Not true in earlier era, where prognosis decreased with number of lymphocytes- see C5 above.
  • 4. Limited stage, low bulk disease treated with radiation therapy
  • 5. Higher stage, symptomatic (IIB-IV) treated with multi-agent chemotherapy+/- radiation therapy
• K. Complications of therapy
  • 1. Radiation/chemotherapy effects to lungs, heart, bone marrow
  • 2. Sterility
  • 3. Splenectomy associated sepsis
  • 4. Therapy associated second malignancies
• L. Pathobiology
  • 1. The etiology of Hodgkins lymphoma is still unknown, and until very recently, the lineage of the R-S cell was also obscure
  • 2. The mixed cellular infiltrate, unusual large cells, clustered familial cases, and early evidence of immune dysfunction suggest an infectious etiology
    • a Approximately 30% of cases/Reed Sternberg cells contain Epstein Barr virus within the RS cells
  • 3. Recent molecular studies, utilizing single cell dissection and PCR based sequencing of the antigen receptor genes indicate that the Reed-Sternberg cell in the majority of cases is in fact an altered B cell.
  • 4. Therefore Hodgkin's lymphoma is a type of B cell lymphoma, but one with a very different biology than the other types of B cell lymphoma, and hence still deserves a separate category in the classification system.
  • 5. The molecular abnormalities within the different types of R-S variants effect the expression of lineage associated antigens
    • a. L and H cells of lymphocyte predominant Hodgkin's disease express B cell antigens, and are clonal proliferations of this cell type
    • b. Reed Sternberg cells of other types may express T cell, B cell and macrophage associated antigens, but at the molecular level, show B cell gene rearrangements, often with out of frame mutations.

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