Morphological quality and nucleic acid preservation in cytopathology.

Abstract

Aim: Fixation is a chemical or physical procedure to prevent the degradation of protein and tissue morphology. To optimize molecular analyses on archival tissues, it is essential that fixation preserves morphology along with protein epitopes and DNA/RNA integrity.

Methods: We employed a new formalin-free alcoholic-based fixative, named FineFix®, in 15 cases of serous effusions and 38 cases of Fine-Needle Aspirates, in order to evaluate the cellular morphology, and the quality of nucleic acids.

Results: The cyto-morphology of the cellular component of effusions and Fine-Needle Aspirates obtained with FineFix® fixation was similar to that obtained with the matched formalin-fixed counterpart. Immunocytochemistry showed comparable results with the traditional fixative, but the formalin-free fixation preserved higher molecular weight DNA and RNA as demonstrated by successful PCR of large amplification products of more 2000 bp.

Conclusions: The formalin-free fixative produced not only satisfactory results for immunocytochemistry on cytological smears and cell blocks, but also excellent preservation of DNA/RNA that can be efficiently employed also for sophisticated molecular techniques.