Hodgkin's Lymphoma

Question 1

What are the 4 histological subtypes of Hodgkin’s lymphoma

Answer 1

1) Nodular sclerosing HL
2) Mixed cellularity HL
3) Lymphocyte rich HL
4) Lymphocyte depleted HL

Question 2

List the immunophenotypic features of HRS cells

Answer 2

1) CD30+, CD15+ (in 75%), weak PAX5 positivity, IRF4/MUM1 positive
2) Loss of B cell antigens (although weak CD20 expression in ~20%)
3) EBV expression varies across subtypes

Question 3

How is lymphocyte rich HL the same as and distinguished from NLPHL

Answer 3

• Morphologically, both contain abnormal, large lymphoma cells that are surrounded by small, reactive lymphocytes
• Both lack the inflammatory infiltrate (eosinophils, plasma cells etc…) seen in other subtypes of HL
• NLPHL is characterised by T cell rosetting around the NLPHL cells. These T cells have a T-follicular helper cell phenotype (CD4+, +/- CD8+, CD57+, PD1+)
• Immunophenotype of the lymphoma cells differs: LRHL will have classical HL phenotype (Loss of B cell antigen expression, weak PAX5, CD30+, CD15+, IRF4/MUM1+) whereas NLPHL will have a B cell immunophenotype (CD19+, 20+, 79a+, PAX5). Also characteristically BCL6 positive and MUM1/IRF4-.

Question 4

List the poor prognostic features of CHL

Answer 4

• Age
• Male sex
• > 3-4 nodal groups involved
• Bulk disease (mediastinal mass >1/3rd)
• Extranodal sites of disease
• B symptoms
• Elevated ESR and LDH
• Elevated WCC
• Anaemia
• Lymphopenia
• Low albumin

Question 5

List the immunophenotypic features of NLPHL

Answer 5

• LP cells derived from germinal centre B cells.
• Positive for pan-B markers (CD19, CD20, CD79a, PAX5)
• They contain germinal centre markers: BCL6 (including BCL6 translocations), HGAL but lack CD10.
• Characteristically BCL-6, EMA and J-chain positive.

Question 6

List the features that distinguish NLPHL from THRLBCL

Answer 6

• Nodular pattern of infiltration common (vs diffuse in THRLBCL)
• Large, atypical lymphoma cells surrounded by T cells (rosetting) that have a follicular centre T helper cell phenotype (CD4+/ CD8+/ CD57+/ PD1+ T cells favours a diagnosis of NLPHL)
• FDC networks present
• Dominant background of B lymphocytes (versus T lymphocytes in THRBCL)
• Histiocytes less prominent in NLPHL