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Hodgkin Lymphoma

 

 

Histopathology

 

The pathologic diagnosis of classical Hodgkin lymphoma is based on the detection of:

Hodgkin Lymphoma Reed-Sternberg cells (RS cells):

  • Malignant cells of Hodgkin lymphoma and the diagnostic cell of classical Hodgkin lymphoma.
  • Minority of cells present (0.1 - 10% of total - typically about 1%)
  • In the midst of other reactive inflammatory cells:
    • histiocytes, plasma cells, lymphocytes, eosinophils & neutrophils
    • PLUS fibrosis in nodular sclerosis (due to cytokine release) 
  • Reed-Sternberg cells are derived from clonal proliferation of B lymphocytes.

 

The microscopic appearance of a binucleated Hodgkin Lymphoma Reed-Sternberg cell (HL-RS cell - usually called RS cell):

 

  • There are classic RS cells and variant RS cells:
    • Mononuclear variants
    • Lacunar cell - seen in nodular sclerosis subtype
    • Mummified cells

 

Pathologic findings of a classic Hodgkin Lymphoma Reed-Sternberg (RS) cell:

Malignant cell

Hodgkin Lymphoma Reed-Sternberg (RS cell)

Cellular origin
  • Germinal centers of B lymphocytes; very rarely from T lymphocytes
  • lose ability to express antibodies due to absence of immunoglobulin gene expression

 

Cellular appearance
  • Large cell (> or = 15 - 45 um in diameter)

 

  • Binucleated (2 nuclei or 2 nuclear lobes)

 

  • Abundant slightly basophilic cytoplasm

 

  • Two large and prominent eosinophilic, inclusion-like nucleoli (in each nuclear lobe).

Immunophenotyping of

B cell antigen

Positive:

  • CD30 (100% of cases)
  • CD15 (75% of cases)
  • CD20 (5 - 10% of cases)

 

Negative:

  • CD45, CD19 and CD79a

 

Proportion of cellular composition

Reed-Sternberg cells:

  • <1% of involved tissue

Other inflammatory cells (abundant):

  • lymphocytes, eosinophils, neutrophils, macrophages and plasma cells

 

   

 

Positive CD30 stain (brown) in RS cells:

   

 Positive CD15 stain (brown) in RS cells:           

Constitutive activation of nuclear factor kappa B (NfkB) pathway to prevent apoptosis is thought to be the mechanism of formation of malignant RS cells.

As a result of this activated pathway, RS cells overproduce tumor necrosis factors, cytokines and chemokines. 

Typically, RS cells appear either in classical form or in other variants such as lacunar or reticular.

RS Cell form

Description

Classical
  • Bilobed, Binucleated or Multinucleated with prominent eosinophilic-like nucleoli

 

Lacunar
  • Occurs in Nodular sclerosis variant
  • Nucleus typically twisted or lobulated
  • Appears to sit in a space (lacuna) due to a membrane retraction artifact occurring in formalin fixation

 

Mummified cells
  • Condensed cytoplasm and dark pyknotic nucleus (undergoing apoptosis)

 

 

 

 

 

 

 

 

 

 

 

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