Histopathological assessment and immunohistochemical study of nasopharyngeal low grade MALT lymphoma

الملخص EN

Introduction : MALT lymphoma arises in a variety of body tissues, but most often in the stomach.

Though rela¬tively rare, these MALT lymphomas may arise within several sites in the head and neck, and often present diag¬nostic and therapeutic challenges.

Immunohistochemical analysis arc helpful in confirming the diagnosis between the MALT-lymphoma and the reactive lymphoid hyperplasia.

MALT-lype lymphoma demonstrated characteristic negative staining for CD3, CD5 and CD43, positive staining for CD20, and monotypic staining for cither kappa or lambda light chain immunoglobulin markers, whereas reactive lymphoid hyperplasia all expressed B and T cell markers.

Material and Methods : 41 cases of nasopharyngeal masses were obtained from the files at pathology department, Mansoura Faculty of Medicine through the period from 2002 till 2006.

31 cases were corresponded histomorpho-logically to low-grade B-ccll lymphoma of mucosa-associatcd lymphoid tissue (MALT) type and 10 patients with reactive lymphoid hyperplasia of the adenoid.

Hcma-toxylin-eosin-stained slides were reviewed to confirm the diagnosis.

Immunohistochcmical studies were performed on formalin-fixed, paraffin-embedded sections using the labeled streptavidin-biotin-pcroxidase complex method with DAB as chromogen.

The following antibodies were evalu¬ated CD20, CD3, Kappa, lambda and cytokcratin antibodies.

Results : All cases of low grade MALT lymphoma show lymphocpithelial lesion and proliferation of centro¬cyte like cells.

14 cases (45.1 %) show subepithelial plasma cells.

Dutcher bodies were demonstrated in 10 cases (32.2 %).

Monocytoid B-cells were seen in 12 cases (38.7 %).

Six (60 %) out of the ten cases of adenoids show transmigrating lymphocyte without formation of lymphoc¬pithelial lesion.

All cases with MALT-type lymphoma expressed CD20 and not CD3 whereas 10 cases of adenoid, all expressed B and T cell markers.

Immunohistochemical staining showed that 31 cases of low grade MALT lym¬phoma were positive for immunoylobin light chain i kappa or lambda) while 10 cases of adenoid were positive for both kappa and lambda light chain.

Conclusion : Immunohistochcmical analysis are help¬ful in confirming the diagnosis between the MALT-lymphoma and the reactive lymphoid hyperplasia of the nasopharynx.