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Case 139 - Discussion

Hematopathology Case

 

CD20

CD5

BCL2

BCL2

BCL2

BCL6

CD10

CD21

 

CD21

 
 

Marginal zone lymphoma with follicle colonization

Marginal zone lymphoma (MZL), both nodal and extranodal, may have colonization of lymphoid follicles, which can have a nodular growth pattern and closely resemble follicular lymphoma. Several helpful hints:

  1. In MZL with follicle colonization, BCL2 immunostain usually shows weaker positivity in the center of the nodules with stronger staining in the periphery, whereas follicular lymphoma has the reverse pattern;

  2. In MZL with follicle colonization, the BCL6 and CD10 positive cells are much fewer than the CD20 positive cells in the nodules; the BCL6 and CD10 positive cells are usually in the center of the nodules, and the extent of these cells are much smaller than the CD21/CD23+ meshwork;

  3. CD43 is positive in ~50% of extranodal MZL, whereas follicular lymphoma is typically negative;

  4. Follow cytometry: no coexpression of CD10 and BCL2 in the same population;

  5. FISH study for IGH@/BCL2 rearrangement is negative in MZL;

  6. Be cautious when making a diagnosis of follicular lymphoma in the organs where the extranodal MZL often occurs, including salivary glands, lacrimal glands and stomach.