Microwave-Assisted Formalin Fixation of Fresh Tissue: A Comparative Study

Over the past two decades, there has been a growing interest in reducing the turnaround time required to preserve and process specimens into paraffin blocks for sectioning, and subsequent evaluation by light microscopy (LM) for surgical pathology (PATH) or research (Login, 1978 ; Leong, 1991 , Leong, 1993 , Leong, 1994 ; Hopwood, 1993 ; Boon et al., 1986 ; Kok and Boon, 1990a ; Battifora, 1999 ; Ruijter et al., 1997 ; Gamble, 1998 ). Tissue samples are typically placed in plastic cassettes for all processing steps. Equipment has been on the market for a number of years to facilitate rapid processing. Processing, after sample preservation, is done either by automatic tissue processors (Leong, 1991 , Leong, 1993 , Leong, 1994 ; Hopwood, 1993 ; Gamble, 1998 ; Battifora, 1999 ) or by microwave (MW)-assisted processing (Boon et al., 1986 ; Kok and Boon, 1992 , Kok and Boon, 1996 , Kok and Boon, 1997 ; Crowder and Giberson, 1998 ). Either process cycles the tissue cassettes, after preservation, through dehydration (usually a graded series of ethanol), intermedium (usually xylene, isopropanol, chloroform, or other xylene substitute), and molten paraffin. MW-assisted methods are generally considered to result in quicker turnaround times (Boon et al., 1986 ; Kok and Boon, 1992 ; Crowder and Giberson, 1998 ) than those obtained with automated processors (Leong, 1991 , Leong, 1994 ; Kok and Boon, 1992 ).