Angioimmunoblastic lymphoma (AILD-type T-cell lymphoma) with hyperplastic germinal centers.

Angioimmunoblastic T-cell lymphoma (or angioimmunoblastic lymphadenopathy with dysgammaglobulinemia [AILD]) was originally considered to be an abnormal immune reaction in which reactive follicles with germinal centers (GCs) are usually absent. When hyperplastic GCs are present along with an angioimmunoblastic reaction, the lesion has been interpreted as a benign hyperimmune reaction. We report seven patients with angioimmunoblastic T-cell lymphoma (AITL) who initially had hyperplastic GCs, shown to be malignant lymphoma by further studies and clinical follow-up. Clonal T-cell populations were observed in all specimens evaluated, and sequential biopsies showed histologic progression to typical AITL in two patients. Clinical presentation was characterized by generalized lymphadenopathy of acute onset, constitutional symptoms, hepatosplenomegaly, skin rash, and polyclonal hypergammaglobulinemia in five patients; regional adenopathy preceded generalized adenopathy in two patients. Five patients had rapid progression of disease, and three patients whose treatment was delayed due to inadequate evidence to diagnose lymphoma died of infection. The initial biopsy findings of each patient were similar and showed angioimmunoblastic proliferation, hyperplastic GCs with ill-defined borders, and interfollicular tingible-body macrophages. These GCs differed from occasional residual follicles of typical AITL in that the GCs were enlarged and hyperplasia of follicular dendritic cells was not seen. Diagnostic clear cells were not observed. Apoptotic bodies were markedly increased and bcl-2+ lymphocytes were sparse compared with typical AITL. Results of in situ hybridization for Epstein-Barr virus were positive in each case. We conclude that hyperplastic germinal centers with ill-defined borders and frequent interfollicular tingible-body macrophages occur in a histologic variant of AITL that is necessary to recognize for early diagnosis and treatment.