Genomic profiling of myeloid sarcoma by array comparative genomic hybridization

Myeloid sarcoma (MS) is a tumor mass of myeloblasts or immature myeloid cells occurring in an extramedullary site. In this study, seven cases of MS [stomach (1), testis (1), skin (2), and lymph node (3)] and 3 synchronous and 1 follow‐up bone marrow (BM) samples were studied for genomic abnormalities using array comparative genomic hybridization (array‐CGH). Array‐CGH construction used ∼5,400 bacterial artificial chromosome clones from the RPCI‐11 library, spanning the human genome. Data were analyzed using the DNAcopy software and custom heuristics. All MS cases had genomic abnormalities detected by array‐CGH. Unbalanced genomic abnormalities in five MS cases were confirmed by conventional cytogenetics (CC) and/or fluorescence in situ hybridization (FISH); these abnormalities included loss of 4q32.1‐q35.2, 6q16.1‐q21, and 12p12.2‐p13.2 and gain of 8q21.2‐q24.3, 8, 11q21‐q25, 13q21.32‐q34, 19, and 21. Array‐CGH was also invaluable in identifying possible deletions, partner translocations, and breakpoints that were questionable by CC. The remaining two MS cases had genomic aberrations detected by array‐CGH, but were not studied further by CC/FISH. Chromosome 8 was most commonly abnormal (3/7 cases). Identical genomic abnormalities were demonstrated in MS and in synchronous BM in two cases. These results demonstrate that array‐CGH is a powerful tool to screen MS tissue for unbalanced genomic abnormalities, allowing identification of chromosome abnormalities when concurrent BM is nonanalyzable or nonleukemic. © 2005 Wiley‐Liss, Inc.