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Case 139 - Discussion

Hematopathology Case













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.