Anaplastic lymphoma kinase–positive large B-cell lymphoma with complex karyotype and novel ALK gene rearrangements

SummaryAnaplastic lymphoma kinase–positive large B-cell lymphoma is a rare non–Hodgkin lymphoma that exhibits a characteristic immunoblastic/plasmablastic morphology and is frequently associated with t(2;17)(p23;q23) and expression of Clathrin–anaplastic lymphoma kinase fusion protein. Here, we report a refractory anaplastic lymphoma kinase–positive large B-cell lymphoma in a 49-year-old human immunodeficiency virus–positive man. The neoplastic cells expressed CD138, epithelial membrane antigen, CD45, and perforin, and showed a strong granular cytoplasmic anaplastic lymphoma kinase staining pattern. Conventional chromosome analysis revealed a clone with multiple anomalies and a chromosome count of 76 to 79. Fluorescence in situ hybridization studies showed 5 copies of the ALK gene with 2 intact signals and 3 signals resulting from 2 independent, previously unreported, rearrangements. One rearrangement, seen in 2 copies, involved translocation of ALK sequences to chromosome Xq21. The second rearrangement involved translocation of ALK sequences to chromosome 12q24.1. This case broadens the cytogenetic alterations in anaplastic lymphoma kinase–positive large B-cell lymphoma, and it also demonstrates the high genetic instability of this tumor.