lymphoma of the stomach are almost all non Hodgkin's type and of B-cell
These lymphomas usually arise from MALT (mucosa
associated lymphoid tissue)- also known as Marginal Zone B - cell
lymphoma (Low and High grade).
Diffuse large B-cell lymphoma
include high grade lymphoma of MALT origin and non-MALT type and they
Other types include mantle cell
lymphoma (malignant lymphomatous polyposis) , follicular lymphoma,
Burkitt's lymphoma and rare solitary plasmacytoma.
Helicobacter pylori infection is a risk factor for gastric lymphoma
Some MALT lymphomas have been reported in
immunocompromised patients (in AIDS and following organ
High grade lymphoma
following organ transplantation may be related to Epstein-Barr virus.
Diagnosis of gastric lymphoma is made on the morphological features.
Lymphoma should not be diagnosed or refuted on the basis of clonality
studies by immunohistochemistry or molecular techniques alone.
Commonly located in the
May be polypoid and fungating
like gastric carcinoma.
In low grade cases,
multiple erosions or superficial ulceration may be present.
- Diffuse polymorphous population of B-cells expanding the lamina
propria. Reactive lymphoid follicles are present. Numerous plasma cells
are also noted, some of these may have Dutcher bodies (true
intranuclear inclusion made up of immunoglobulin).
- Small or medium sized irregular (centrocyte-like) cells forming
lymphoeithelial lesions and destroying the epithelium, leaving
epithelial remnants and sometimes invading the follicles.
some, cases the neoplastic cells resemble small lymphocytes or
monocytoid B cells with abundant pale staining cytoplasm.
Lymphoepithelial lesions defined as glandular structures expanded and
destroyed by groups of more than 3 lymphoid cells.
Immunostaining for CD20, CD79 and cytokeratin are useful for
demonstrating lymphoepithelial lesions. CD5, CD10, CD23 or cyclin D1 are
Occasional non destructive lymphoepithelial lesions alone are not
sufficient to diagnose lymphoma.
Carefully look for compact clusters, confluent aggregates or sheets of
blast cells that makes the tumour high grade.
Problem in distinguishing low grade lymphoma from heavy chronic
inflammatory cell infiltrate in chronic gastritis (lymphoepithelial
lesion is diagnostic of lymphoma).
- Lesion does not regress with H. pylori eradication.
- Destructive infiltrate of clusters or sheets of blast cells.
- Few or no lymphoepithelial lesions.
- Mitoses and apoptotic bodies frequent.
- Problem in distinguishing from diffuse carcinoma, sarcoma, or even
T-cell lymphoma or metastatic melanoma. Epithelial lesions infiltrated
by melanoma cells may mimick lymphoepithelial lesions.
- Mucin stains and immunostaining for cytokeratin , CEA , common
leucocyte antigen, B and T cell markers are very helpful.