Histiocytic necrotizing lymphadenitis. An ultrastructural study in comparison with other types of lymphadenitis.

The lymph nodes from 10 cases of histiocytic necrotizing lymphadenitis (HNL), 3 cases of necrotizing lymphadenitis with follicular hyperplasia (NLFH), and 11 cases of various types of lymphadenitis (abscess-forming, tuberculous, Piringer-type, "viral", and nonspecific lymphadenitides) were comparatively studied. The NLFH, clinically representing a milder form of collagen disease, showed necrotizing lesions similar to those of HNL but with follicular hyperplasia, more plasma cells, and scattered neutrophils; the latter features closely resemble those of some lymph nodes in systemic lupus erythematosus (SLE). Ultrastructurally, HNL and NLFH both showed coagulative necroses of individual lymphocytes, the macrophages with large cellular debris, prominent immunoblasts, and cytoplasmic inclusions such as frequent tubuloreticular structures (TRS) and "intracytoplasmic rodlets" (ICR). The necrotic modality in abscess-forming and tuberculous lymphadenitides was different and the macrophages contained smaller debris. The immunoblasts were less prominent in "viral" lymphadenitis and much less in the others. While TRS were present in may cases of other lymphadenitides as well, they were positive in a much smaller number of cells only; the ICR were found exclusively in HNL and NLFH. These findings suggest a relationship between HNL and NLFH; they may form a spectrum of hyperimmune reaction that includes SLE as an extreme manifestation.