Histological, immunohistological and autopsy findings in lymphogranulomatosis X (including angio-immunoblastic lymphadenopathy).

172 cases of lymphogranulomatosis X (LgX) were studied by light microscopy. In 53 cases immunohistological techniques for detecting intracytoplasmic immunoglobulins were applied. In the lymph nodes of all cases the nodal architecture was found to be effaced. Active germinal centres were absent, and there was a generalized, markedly increased proliferation of epithelioid venules. A polymorphic infiltrate was present in all cases. It was dominated by immunoblasts in 14%, by plasma cells in 16%, by epithelioid cells in 23% and by lymphocytes in 6% of the cases. In the remaining 41% of the cases no special type of cell predominated (mixed cell type of LgX). The clusters of clear cells present in some cases with immunoblastic predominance did not stain for intracytoplasmic immunoglobulins; in contrast, the basophilic immunoblasts exhibited a polyclonal Ig pattern. In some of the cases with lymphocytic predominance most of the lymphocytes showed abundant cytoplasm with azurophil granules. Transformation into malignant lymphoma was proven at autopsy in 5 of 38 cases (13.2%). Malignant transformation (biopsy and autopsy material) was confirmed in a total of 11 of 172 cases (6.4%) and suspected in an additional 7%. Among the malignant lymphomas were one immunologically proven B-immunoblastic lymphoma, one peripheral T cell lymphoma and 5 cases of Hodgkin's disease. An association between LgX and carcinoma was histologically verified in 7 cases. 26 cases with active germinal centres and 11 cases with only locally pronounced vascularization but with histological and cytological changes that were otherwise similar to LgX were designated as hyperimmune reactions (HR). These cases had a significantly better prognosis. Two cases that presented as HR with active germinal centres later developed into LgX. It is suggested that the disappearance of active germinal centres is important in the pathogenesis of LgX. The possibility that this may correspond morphologically to an alteration of different components of the T-cell system is discussed.