Sharon H. de Kock September 2012. LYMPHOID NEOPLASM Lymphomas arise from the constituent cells of...
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Multisystem Diseases Sharon H. de Kock September 2012
Sharon H. de Kock September 2012. LYMPHOID NEOPLASM Lymphomas arise from the constituent cells of the immune system or from their precursors and are the
LYMPHOID NEOPLASM Lymphomas arise from the constituent cells of
the immune system or from their precursors and are the consequence
of genetic aberrations that impair proliferation, differentiation,
and ability to undergo apoptosis of lymphatic cells.
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ORIGIN OF LYMPHOID NEOPLASMS
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WHO CLASSIFICATION
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EPIDEMIOLOGY Hodgkin disease (HD) and non-Hodgkin lymphomas
(NHLs) constitute 10%15% of all childhood cancers in developed
countries and are third in frequency after acute leukemias and
brain tumors. Non-Hodgkin lymphoma (NHL) is the most common type of
lymphoma. Although there are more than 50 types of NHL, diffuse
large B-cell lymphoma (DLBCL) is the most common type, making up
about 30 percent of all lymphomas. DLBCL affects about 7 out of
100,000 people each year.
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EPIDEMIOLOGY cont. HD has a bimodal age distribution: peak in
20-30 yr age grp and the second smaller peak after 50 yrs. NHD
increases exponentially with age after 20 yrs. NHLs are twice as
frequent in male children as in females. The subtypes of lymphoma
differ in frequency between the adult and paediatric grps, a strong
bias towards precursor B- and T- lymphoblastic and Burkitt lymphoma
in childhood. Higher frequencies in whites than blacks or
Asians.
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EPIDEMIOLOGY cont. Risk is higher with a positive family
history. Oncogenic lymphotrophic DNA and RNA viruses have been
implicated in many NHL types. Most important agent EBV, trigger
lymphoma in congenital immuno-defiencies, iatrogenically
immuno-suppressed organ transplant recipients, pts receiving
maintenance chemotherapy and immuno- suppressive therapy for
collagen disorders. Also the retrovirus human lymphotrophic virus
type 1 (HTLV-1) and human herpes virus 8 (HHV-8)
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EPIDEMIOLOGY cont. Bacterial overgrowth can also promote
lymphomagenesis. Helicobacter pylori has been shown to be necessary
for the development of gastric lymphoma.
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PATHOLOGY The Reed-Sternberg cell is the malignant cell in HD:
Its identification, against the appropriate background of
inflammatory cells and fibrosis, is required to make the diagnosis
of HD. Four histologic subtypes of HD are described: lymphocytic
predominance (5%), mixed cellularity (20- 25%), lymphocytic
depletion (