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DESCRIPTIONMultisystem Diseases. Sharon H. de Kock September 2012. LYMPHOID NEOPLASM. - PowerPoint PPT Presentation
Multisystem DiseasesSharon H. de KockSeptember 2012LYMPHOID NEOPLASMLymphomas 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. ORIGIN OF LYMPHOID NEOPLASMS
EPIDEMIOLOGYHodgkin 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.
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.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)EPIDEMIOLOGY cont.Bacterial overgrowth can also promote lymphomagenesis. Helicobacter pylori has been shown to be necessary for the development of gastric lymphoma.PATHOLOGYThe 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 (