Reactive lymphoid hyperplasia of the liver characterized by an angiofollicular pattern mimicking Castleman's disease

A case of reactive lymphoid hyperplasia of the liver exhibiting a characteristic angiofollicular pattern is reported. A hepatic nodular lesion was discovered by abdominal echography during clinical follow-up of abnormal liver function tests. It was diagnosed as hepatocellular carcinoma because of its hypervascularity when observed by angiography, and surgically resected. Grossly, the lesion was well-demarcated and measured 2 cm in diameter. Microscopically, the nodule was composed of lymph follicles with germinal centers, and the hyalinized inter-follicular space contained abundant hyalinized vasculature and plasma cells. The surrounding liver tissue exhibited chronic inflammation with some peculiar angiofollicular structures mimicking Castleman's disease. An immunohistochemical study revealed that the angiofollicular structure had the same characteristics as a lymph follicle with a germinal center, and that the plasma cells proliferating in the inter-follicular space had polyclonal immunophenotypes. These histological and immunohistochemical findings indicated that the angiofollicular structure observed was a kind of reactive lymph follicle, and that this hepatic lesion was reactive lymphoid hyperplasia rather than Castleman's disease or an inflammatory pseudotumor.