[Immunohistological study of reactive follicular hyperplasia of lymph node in childhood]

Reactive follicular hyperplasia (RFH) of lymph nodes, which is often found in the peripheral nodes in children, is usually caused by viral, bacterial, or other specific infections, and sometimes complicated with dermatopathic lesions, or immunological disorders. Those nodal lesions might result from one of the various immunological reactions to some antigen. In this histologic and immunohistologic study, we mainly investigated the cells in the involved nodes. As the results, in the cases of the conspicuous follicular hyperplasia, there were prominent increase of the T-cell with positive UCHL1, the antigen presenting cells with positive S100 protein in T-nodule, and the B-cell with positive L26 in germinal center and cortical sinuses. The nodes with conspicuous follicular hyperplasia also showed foci of infiltration of the polymorphous leukocytes or the lysozyme positive mono-macrophages in the cortical sinuses at the early or acute stage. Decreasing the grade of RFH, the polymorphous or the macrophage infiltration disappeared, while S100 protein positive histiocytes remained as the persistent nodules or aggregates in the cortical sinuses. It was also noted that the B-cells with polyclonal surface immunoglobulins, IgM, kappa, or lambda, increased in number in the case of conspicuous RFH. The RFH might be the result of increased activity of the cellular and humoral immunity, with which T-cells, B-cells, antigen presenting cells, and mono-macrophages are concerned.(ABSTRACT TRUNCATED AT 250 WORDS)