*2.4.1.4 Immunophenotyping of reactive lymphoid infiltrates*


To sum up, majority cases of reactive infiltrates have mild cytology atypia, severe atypia cases were not found at all, monocytoid B-cells were absent, and lymphoid cells did not undergo plasmocytoid differentiation.

Thereby, lymphoid infiltrate of MALT-lymphoma, in contrast to reactive infiltrate, has tendency to be more destructive and expansive. One third of all the MALT-lymphoma cases has mild cytology atypia. As cytological atypia grows, monocytoid cells appear more frequently, amount of plasma cells progressively decrease, moreover, the frequency of follicle appearance decrease, while the majority of cases have follicle colonization.

## *2.4.2 Peripheral small B-cell lymphoma of the stomach*

The study was performed in 21 cases aged 14 to 83 years, mean age was 48 years. The cases were represented by follicular lymphoma of I, I – II, II cytological degree (n = 10), lymphoma from cells of the mantle zone (n = 6), Burkitt's lymphoma (n = 5). Defects of the mucous membrane from surface erosion to ulcer were noted in two-thirds of the material examined. Inflammation was mild or moderate in all variants of lymphomas. *Helicobacter pylori* infection was observed in 8 cases (38.1%). Infiltration growth was focal diffuse in about a third of cases with mantle cell lymphoma and follicular lymphoma, and diffuse in 2/3 of cases. In Burkitt's lymphoma the infiltration growth was diffuse in all 5 cases. Burkitt's lymphoma consists of cells of medium size, but it can be misinterpreted as small cell lymphoma due to artificial deformation after the tissue fixation. Morphological characteristics of follicular lymphoma, lymphoma from cells of the mantle zone, Burkitt's lymphoma are compared in **Table 4**.

Thereby, morphological features, typical for MALT-lymphoma (atypical lymphoid small cells, reactive follicles, LELs) can be seen in other peripheral B-cell lymphomas, that is why ICH-research is decisive.

Among peripheral small-cell B-cell lymphomas, 7 cases of follicular lymphoma and 4 cases of mantle cell lymphoma were studied by immunohistochemistry. All studied lymphomas (lymphoma from cells of the mantle zone, follicular lymphoma) were B-cells and contained single or small groups of diffuse T-cells. In this case, the diagnosis of follicular lymphoma was made on the basis of the totality of CD23, CD38, CD10 occurring in various combinations. It should be noted that all 3 cases of gastric follicular lymphoma were CD10-negative, while the cells of the tumor infiltrate were either CD38-positive or CD23-positive. For lymphoma from cells of the mantle zone the reaction with CD5 was diagnostically significant: all cases were positive. Morphological characteristics of lymphoid cell infiltrations in gastric mucosa for lymphomas and reactive infiltrations are compared in **Table 5**.


#### **Table 4.**

*Peripheral small B-cell lymphomas, Burkitt's lymphoma: Morphological characteristics of lymphoid cell infiltration in gastric mucosa.*

*MALT Stomach Lymphomas: Aspects of Diagnosis and Treatment DOI: http://dx.doi.org/10.5772/intechopen.97865*


### **Table 5.**

*Diagnostically meaningful morphological characteristics.*
