VI. Big picture
(This is a difficult subject and lecture because of the accumulation
of confusing historical terminology, subtle cytologic differences,
and the current use of morphologic, immunologic and molecular
tools in the diagnosis of these diseases. IT'S NOT MY FAULT! So
I'm starting with some basic rules of the road. We will then discuss
them in greater detail. Finally, you will have an opportunity
to review and use this information in a later clinical seminar)
- A. As with other organs, lymph nodes, and more globally, the
immune system, can be the site of infectious, immune and neoplastic
disease, the latter both primary and metastatic
- B. The clinical manifestations of disease in the lymph nodes
are
- 1. Local enlargement, tender or nontender, +/_
- 2. Compression/obstruction of adjacent structures +/_
- 3. "Systemic" symptoms of fever, weight loss and
night sweats
- C. Infectious organisms can stimulate the same acute, chronic
or granulomatous reactions in the draining lymph nodes as they
characteristically stimulate at other sites
- D. Several types of immune stimuli can cause "reactive"
enlargement of the entire lymph node, or selective expansion of
cortical, paracortical or medullary regions
- E. Metastatic tumors spread to the lymph nodes primarily via
lymphatic drainage from adjacent solid organs
- F. Primary neoplasms of the lymph nodes are all malignant
- G. They are divided into malignant (non-Hodgkin's) lymphomas,
and Hodgkin's lymphoma
- H. Malignant lymphomas are more common, and can be simply
divided into indolent, or slow growing, slowly progressive types, and rapidly growing aggressive types
- I. Malignant lymphomas represent clonal malignancies in which
the majority of cells are frozen at a single stage of normal lymphocyte
differentiation
- J. Lymphomas frozen at a stage associated with high replication
rates yield aggressive lymphomas; lymphomas frozen at stages associated
with recirculation or final function yield indolent lymphomas
- K. The diagnosis of malignant lymphomas is based on
- 1. The microscopic loss of normal nodal histology and cytologic heterogeneity, and
- 2. Replacement by a dominant
cytologic cell type,
- 3. Supplemented by immunologic and molecular
techniques defining lineage, clonality, molecular pathogenesis
- L. The prognosis and treatment of lymphomas is based on
- 1. Thedominant cell type (and it's inherent biologic behavior)
- 2. The extent of spread (Stage) and
- 3. The underlying health of the patient
- M. All of the previous statements are complicated by the fact
that indolent lymphomas can further mutate to aggressive types
- N. Hodgkin's lymphoma is a less common nodal disease whose
diagnosis is based on the detection of a characteristic cell, the
Reed-Sternberg cell, in the appropriate histologic setting
- O. There are five histologic subtypes, but prognosis is based
primarily on extent of disease
- P. Hodgkin's lymphoma is a more curable disease than malignant
(non-Hodgkin's) lymphomas
-
Q. Now watch me confuse this relatively straightforward information
with the details
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