Gastointestinal tract lymphomas
A. Androulaki1, I. Chiconti2, E. Patsouris3, Ch. Kittas4
Depts. of Pathology, Laikon Hospital1, Ag. Olga General State Hospital of N. Ionia2, Department of Pathology University of Athens and Department of Histology University of Athens3,4
Extranodal lymphomas originate from tissues other than lymph nodes and represent the 25-40% of all Non Hodgkin's lymphomas (NHL). Hodgkin's disease is very rare outside the lymph nodes.
At these sites tumor arise from specific mucosa associate lymphoid tissue (MALT), which may be a normal tissue component as the mucosa of the intestine, or acquired, as in the stomach. The majority of extranodal NHL occur in the gastrointestinal tract and they represent the 4-18% of NHL in the western countries.
The great majority of this group of lymphomas are B-cell and before the advent of modern immunophenotyping studies many of these B-cell lymphomas were classified as "pseudolymphomas". Certain specific features of the MALT lymphomas (slow evolution,localised growth) could be explained by the homing patterns of MALT lymphomas.Gastric lymphomas of the MALT type are by far the commonest low-grade B-cell lymphomas including IPSID,and may undergo transformation into a high-grade lymphoma.A significant proportion of gastrointestinal B-cell lymphomas,present as high-grade tumours with residual foci of low-grade MALT lymphoma.
Immunoproliferative small intestinal disease (IPSID) is a specific subtype of low-grade B-cell MALT lymphoma distinguished by its epidemiology and association with the synthesis of an abnormal alpha-heavy chain.A variety of others B-cell tumours arise in the gut the most important of which are Burkitt's like lymphomas of the ileocaecal region,and mantle-cell lymphomas which result in the condition called lymphomatoid papulosis.
Other types of low or high-grade B-cell lymphomas corresponding to their peripheral lymph node equivalents, may be presenting primarily in the gastrointestinal tract, but do so infrequently.
Primary gastrointestinal T-cell lymphomas are much less common than B-cell tumours.
Enteropathy-associated T-cell lymphoma (EALT) is the only distinctive T-cell tumor of the gut which, in some ways, is the equivalent of B-cell MALT lymphoma, in that it appears to arise from a gut commited T-cell. Other T-cell lymphomas rarely arise in the gut.
Granulocytic sarcoma, rarely may also occur as primary gastrointestinal tumor.
Key words: Non-Hodgkin Lymphomas, mucosal associated lymphoid tissue, gastrointestinal tract.
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