Bacterial artificial chromosome array-based comparative genomic hybridization using paired formalin-fixed, paraffin-embedded and fresh frozen tissue specimens in multiple myeloma.

Background: Multiple myeloma (MM) is a neoplasm of malignant plasma cells that often harbors many chromosomal aberrations. Currently, fresh frozen tissues (FT) are considered the most reliable for molecular genetic analysis; however, formalin-fixed, paraffin-embedded (FFPE) tissues are easily retrievable. Compared with conventional cytogenetics, bacterial artificial chromosome (BAC) array-comparative genomic hybridization (CGH) allows more sensitive detection of chromosomal abnormalities.

Methods: The authors analyzed 7 paired FT and FFPE samples of bone marrow aspirate materials obtained from patients with MM in parallel to determine the efficacy of BAC array-CGH using FFPE.

Results: Thirty-four aberrations were identified, including 29 that were observed in both sample types, yielding 85% concordance. Nonrandom anomalies, including gains on 7q, 9q, 15q, and 19p and losses on 8p and 13q, were observed in paired samples from at least 2 patients. To verify these results, fluorescence in situ hybridization (FISH) was performed using probes specific for 7q and 15q, and gains were observed in the 4 samples that were examined. Furthermore, 1 of 3 samples from patients who had monoclonal gammopathy of undetermined significance that were tested also carried gain on 7q, suggesting that this aberration may be an early transforming event.

Conclusions: The current results indicated that BAC array-CGH can be effective using FFPE samples and is a sensitive method for the identification of nonrandom chromosomal aberrations in MM.