I. Lymphoid Disorders: Approach – NUS Pathweb

WHERE TO START?

I. Consider the immune system organ by organ:

- Lymph nodes; Bone marrow; Spleen; Thymus; Mucosa Associated Lymphoid Tissue

II. For each organ, ask some questions:

- We will focus on lymphoid tissues here - specifically diseases of lymph nodes

- This is a systematic approach.and you can do the same with the other tissues of the haematolymphoid system.

Diseases of Lymph Nodes:

1. What are the Components of the lymphoid immune system?

2. What are the Functions of the lymphoid immune system?

3. What main Pathologies occur in the lymphoid organs?

Reactive - eg. Reactive lymphoid hyperplasia (lymph nodes, thymus, MALT)
Inflammatory / Infectious - eg. Tuberculosis involving lymph nodes
Neoplastic
- Neoplasms of the lymphoid tissue are usually malignant
- Simplest classification is: Primary vs Secondary
  - Lymphomas
  - Leukaemias
- Some neoplasms can affect BOTH the lymph nodes and the bone marrow. You must have heard of the terms "Lymphom" and "Leukaemia". Do you know the difference? Click on the tab below to see the explanation.
  - Lymphomas refer to haematopoietic malignancies that arise predominantly as masses, either in lymph nodes or in extranodal locations.Leukaemias refer to haematopoietic malignancies that present with widespread involvement of the bone marrow and often the peripheral blood as well. This distinction applies mainly to lymphoid malignancies. - because myeloid neoplasms usually do not involve lymph nodes. Among the lymphoid neoplasms, many of them present mainly as lymphomas (i.e. nodal or extranodal masses). There are several lymphoid neoplasms, however, that also can present as leukaemias. Thus, these neoplasms are often given the name "…… lymphoma/leukaemia", and they are diagnosed as leukaemia if marrow and/or peripheral blood examination reveals the presence neoplastic lymphoid cells in at least specific quantities. Eg. Small lymphocytic lymphoma(SLL)/ Chronic lymphocytic leukaemia (CLL) This is diagnosed as SLL if the main clinical presentation is lymphadenopathy without significant marrow disease, while it is diagnosed aas CLL if the peripheral blood absolute lymphocyte count exceeds a certain value.
What is a simple classification system for lymphomas?
1. First step: Hodgkin vs Non-Hodgkin Lymphoma
2. Second step: NHL -> WHO Classification - B vs T cell; Immature vs Mature
3. Your lecture notes provide a good overview of the classification system