Angiocentric immunoproliferative lesions: a molecular analysis of eight cases.

Angiocentric immunoproliferative lesions (AILs) are believed to represent a unique type of extranodal malignant lymphoma on the basis of clinicopathologic and immunophenotypic evidence. However, molecular studies to assess clonality have been performed on a small number of cases. In this study we assessed the clonality of eight AILs using restriction fragment analysis, the Southern blot technique, and probes to assess the configuration of the T-cell receptor beta, gamma, and delta chain genes and the immunoglobulin heavy and K light chain genes. In addition, the presence of the Epstein-Barr (EB) viral genome was assessed by using both Southern blot analysis (seven cases) and polymerase chain reaction amplification (five cases). Our results demonstrate that gene rearrangements are rare in AILs. A clonal gene rearrangement was identified in only one case, a grade III AIL with a rearrangement of the T-cell receptor delta chain gene. In two additional AILs (both grade III), the EB viral genome was detected as a single band by Southern blot analysis with a probe derived from the terminal repeat region of the virus, suggesting that a single episomal configuration of the EB viral genome was present in each case, as would occur in a clonal population of infected cells. In the remaining cases there was no evidence of clonality, although EB sequences were detected in one of four cases using the polymerase chain reaction. The rarity or absence of gene rearrangements in AILs is difficult to explain if AILs are malignant, presumably monoclonal lymphomas. However, their frequent association with the EB virus may suggest an analogy between AILs and lymphoproliferative disorders that occur in immunosuppressed patients. These findings further emphasize the unique clinicopathologic aspects of AILs and may also be useful diagnostically in the differential diagnosis of lymphoproliferative disorders.