Introduction to Lymphoma
Welcome to the Lymphoma section. This section is divided
into four subsections: Introduction, Hodgkin's
Disease, Non-Hodgkin's Lymphoma, and Clinical
Aspects of Lymphoma
The Lymphoma Introduction, section contains basic
definitions and an overview of lymphoma classification.
The FAB classification of myeloid leukemias does not
correlate with clinical or theraputic outcomes.
Additional clinical aspects of leukemia may be found with
the discussion of the pathology.
Malignant lymphomas (ML) are cohesive malignant
proliferations of lymphocytes arising in lymph nodes and in
lymphoid tissue of various organs (extranodal). Malignant
lymphomas may also be thought of as neoplasms of the immune
system. Rarely, the term lymphoma is used to refer to a
malignant proliferation of true histiocytic cells, but more
on that later.
Lymphoma should be distinguished from leukemia, although
this is not always easily done.
- primarily of lymph node origin,
generally forming a tumor mass
- of bone marrow origin, generally
manifest in the peripheral blood
- can also refer to the systemic proliferation
of an abnormal hematopoietic cell throughout the
marrow and vascular compartments as is seen in some
lymphomas, ie. common in lymphoblastic ML and
The malignant lymphomas constitute a heterogeneous group
of neoplasms arising from the immune system and primarily
involving lymphoid cells.
ML is classified based on 1) the cell type and 2) the
architectural (growth) pattern. In this way, two large
categories: the Hodgkin's and the Non-Hodgkin's lymphomas
For a review of the morphology and immunology of normal
lymphocytes and lymph nodes, click the "Review" button
below. You can return to this page and proceed with the
Introduction to Lymphoma by clicking the "Lymphoma" button
in the Review section.
In lymphoma, normal lymph node architecture is distorted
or effaced by the proliferating malignant lymphoid cells.
The effacement of nodal architecture may be either
diffuse (left) or follicular (center). The
follicular pattern may evolve into a diffuse pattern
(right). The growth pattern is observed at low magnification
while high magnification is used for assessment of cell type
(next card). Note the growth or extension of lymphoma
outside of the capsule. This is typical of lymphoma.
In malignant lymphoma the proliferative cell is usually
monomorphous (one type of cell); in reactive
conditions, the proliferations are polymorphous
(multiple types of cells). In this illustration we see a
proliferation of small lymphocytes in a
diffuse pattern or malignant lymphoma, small
- Here we see a case of malignant lymphoma, small
lymphocytic (ML,SL). Note the proliferation of small
lymphocytes in a diffuse pattern.
Here we see a follicular pattern of growth with
follicular structures growing beyond the capsule. Looking
inside one of the follicles you see a predominance of one
cell type-in this case small cleaved lymphocytes. Thus, you
can make a diagnosis of malignant lymphoma, follicular,
small cleaved cell (ML,SCC, follicular).
Here is an actual case of malignant lymphoma,
follicular, small cleaved cell (ML,SCC, follicular).
Note the follicular pattern of growth. At right is a high
magnification view of a follicle with a predominance of one
cell type-in this case small cleaved lymphocytes.
If these were normal follicles in a reactive node, what
would you expect to see in the follicle at high
Right! You would expect a polymorphous mixture of
lymphocyte cell types in the germinal center of a reactive
node. Reactive lymphoid hyperplasia is characterized by
enlargement of the lymph node, hyperplasia of follicular
(germinal) centers, increased numbers of histiocytes in
sinusoids, and interfollicular hyperplasia of lymphocytes
and plasma cells (often with more immunoblasts).
This example of Reactive lymphoid hyperplasia is
characterized by hyperplasia of follicular (germinal)
centers. Note the variablilty in the size of the follicles
and the presence of a mantle zone in the reactive node. Most
important is the mixture of large and small lymphocytes;
plasma cells (green) and "tingible body" macrophages (blue)
in the reactive germinal center.
A 59 year-old woman complains of a painless lump in her
neck that she first noticed about 4 months ago. It has
enlarged only slightly since she first noted it. The surgeon
said other nearby nodes were involved as well. You are the
pathologist. What do you tell the surgeon?
The area in the box is shown at right.
One more point! We said there were two large categories
of lymphoma: the Hodgkin's and the Non-Hodgkin's lymphomas.
These two types of lymphoma are distinguished by differing
morphologic and clinical features.
Hodgkin's lymphomas are characterized by
the presence of giant bilobed or multinucleate
Reed-Sternberg cells in a reactive appearing cellular
background. In contrast, the non-Hodgkin's lymphomas
generally consist of a uniform proliferation of cells. More
on R-S cells in the discussion of Hodgkin's disease.
Lymphoma is the 6th most common malignancy in the United
States. There were an estimated 43,000 new cases of lymphoma
in the United States in 1990. Non-Hodgkin's lymphoma
accounted for 35,600 cases (83%) and Hodgkin's for 7,400
The incidence of Non-Hodgkin's lymphoma
progressively increases with age (peak approximately 60
years). In contrast, a bimodal peak is seen with Hodgkin's
disease - with a peak between ages 20-29, a plateau between
30-55 and a second rise after age 55.
Lymphoma is more frequent (1.5:1) in males than
females for both Hodgkin's disease and non-Hodgkin's
The major clinical manifestation of malignant lymphoma is
painless lymph node enlargement. Such nodes are
usually firm or rubbery, often multiple and fixed in place,
Systemic symptoms include fever, malaise,
night-sweats, weight loss, and pruritis. As lymphoma
progresses, spread may occur to spleen, liver, bone marrow,
and other organs.
Common primary sites of lymphoma include cervical,
supraclavicular, mediastinal, axillary, periaortic, and
inguinal lymph nodes.
Common extranodal sites of lymphoma include the
gastrointestinal tract, CNS, skin, spleen, bone marrow,
pharyngeal tissues, salivary glands, thymus, and lung among
The physical presence of disease and the presence or
absence of symptoms are the measures for the respective
pathologic and clinical staging of lymphoma.