Necrotizing lymphadenitis. Electron microscopical and immunohistochemical study

Seven cases of necrotizing lymphadenitis (NEL) including a pair of male siblings, a female suffering from non-bacterial meningitis, and two cases with the proliferation of monocytes and/or macrophages in the bone marrow are reported. This disease is clinically documented by the occurrence in young adults usually accompanied by painful cervical lymphadenopathy with fever and leukopenia (below 4,000/mm3). Morphological features were characterized by nuclear debris from degenerated lymphocytes and the appearance of blastoid cells and/or immunoblasts and macrophages. Ultrastructurally, tubular inclusions with a close relation to the endoplasmic reticulum were observed in various kinds of cells in the lesion. Immunohistochemical studies revealed that the ratio of helper/suppressor T-lymphocytes became low at the active stage and returned to normal range at the recovery stage. By immuno-histochemical study it was confirmed that suppressor cells mainly corresponded to large transformed lymphocytes and/or immunoblasts and helper cells were degenerated by an unknown agent. Though the pathogenesis of NEL is still uncertain, it is suggested that T-lymphocytes are mainly involved during the course of the disease and lymphocytes show cellular debris or blastoid transformation.