Ethanol fixation of lymphoma samples as an alternative approach for preservation of the nucleic acids

Abstract

Molecular methods play an important role in diagnostic pathology of lymphomas. PCR based demonstration of clonality or detection of a specific chromosomal translocation may determine the exact classification of the lymphoma. Hence the final diagnosis may depend on the quality of preserved nucleic acids in the bioptic specimen. The integrity of DNA and RNA may be damaged by formalin fixation, which destroys the nucleic acids by fragmentation. Therefore, a portion of each lymphoma sample should be frozen. To substitute freezing techniques we utilized ethanol as a fixative, which preserves nucleic acids. We compared PCR and RT-PCR products from lymphoma samples, which were differently pre-treated by ethanol fixation, formalin fixation and freezing. The ethanol fixed samples retained a high quality of both DNA and RNA and provided reproducible PCR products similar to frozen samples and significantly better then those extracted from formalin fixed samples. We may recommend ethanol as a complementary fixative for all pathology laboratories where deep freezing in not routinely available.