J: Haematological Malignancy

Haematological malignancies were once nearly always treated with radiotherapy, but this has become less frequent with the advent of potent systemic treatments. Radiotherapy still plays a role in certain malignancies, or when residual disease exists.
The medical expert supplement for haematology can be found here

Classification of Lymphomas

There are three important morphological features of lymphomas:

  • Cell size (large or small)
    • Small cells may be cleaved or non-cleaved
  • Growth pattern (follicular or diffuse)
  • Hodgkin's or Non-Hodgkin's lymphoma

WHO Classification

The WHO guidelines for lymphoma classification is based on the:

  • Morphology
  • Immunohistochemistry
  • Genetics
  • Clinical Presentation
  • Clinical Course

of the various lymphomas. Some lymphomas may be diagnosed on morphological features alone (eg. follicular lymphoma, chronic lymphocytic leukaemia). Immunohistochemistry provides additional information in some circumstances (and is required for funding of some therapeutic interventions; eg CD20 for rituximab). Immunohistochemistry also allows establishment of reactive versus malignant follicles (via BCL2 expression).
Another group of lymphomas may be diagnosed on clinical presentation and course alone; such as mycosis fungoides in the tumour phase.
The lineage of lymphoma cells divides the lymphoma diagnoses into broad categories:

  • Mature B Cell Lymphomass
  • Mature T Cell Lymphomas
  • Precursor lymphomas

Problems with Classification

Due to the classification of lymphomas requiring morphological/immunohistochemistry as well as clinical features it is important when tissue is sent to pathology that a full clinical history is provided.
The understanding of lymphomas is constantly evolving and the current classifications may become obsolete with time.
There is still some difficulties with certain lymphoma types:

  • Mediastinal lymphomas can be difficult to distinguish between diffuse large B Cell lymphoma and Hodgkin's lymphoma
  • DLBCL and Burkitt's lymphoma
  • Low grade follicular lymphoma (1 & 2)
  • High grade follicular lymphoma (3A & 3B)
  • The lineage of Hodgkin's lymphoma remains elusive


Mature B Cell Neoplasms

Mature T Cell Neoplasms

Immature B/T Cell Neoplasms

Hodgkin Lymphoma

Myeloid Neoplasms