A systemic lymphoproliferative disorder with morphologic features of Castleman's disease. Pathological findings in 15 patients.

This report describes the nodal and extranodal lesions observed in 15 patients with a generalized disorder that had been histologically diagnosed as Castleman's disease. The disorder was characterized by severe constitutional symptoms, constant involvement of multiple peripheral lymph nodes, and frequent hepatosplenomegaly, in association with clinical and laboratory features reminiscent of a "collagen disease." The clinical course was chronic, with remissions and exacerbations in seven patients, and aggressive and fatal in eight. The material examined included multiple lymph node biopsies, four surgical specimens of spleen, one open lung biopsy, and material from four autopsies. The diagnostic morphological findings were observed in the nodes and were represented by the following histologic triad: diffuse marked plasmacytosis, from the medulla to the subcapsular areas; prominence of the germinal centers; and good preservation of the architecture. One variant of this basic pattern featured abundant immunoblasts and blood vessels. The process appears to be a systemic reactive proliferation of B-lymphocytes, perhaps resulting from faulty immune regulation. Morphologic similarities indicate a relationship between this multicentric disorder and Castleman's disease of plasmacellular type. However, there are distinct differences between them in clinical presentation and evolution, and, consequently, in therapeutic approach.