Multicentric giant lymph node hyperplasia: an immunohistochemical study.

Biopsy specimens from five cases of multicentric giant lymph node hyperplasia were studied by standard histochemical techniques and by immunoperoxidase staining and double immunoenzyme labeling to determine the distribution of intracytoplasmic immunoglobulins and kappa and lambda light chains. Microscopically, the affected lymph nodes showed a nodular pattern characterized by multiple lymphoid follicles permeated by numerous small vessels. A striking proliferation of post-capillary venules with many plasma cells and immunoblasts was observed in the interfollicular areas. Immunoperoxidase staining revealed that the cells were positive for IgG, IgA, and IgM with both kappa and lambda chains in the normal ratio. The IgM-positive cells had a perifollicular distribution, whereas the IgG- and IgA-positive cells were located mainly in interfollicular areas. The presence and distribution of different classes of intracytoplasmic immunoglobulins seemed to reflect a normal, albeit tumultuous, immunologic response. Therefore, the disease can be considered a lymphoproliferative disorder due to an inappropriate immunologic reaction.