RCL2, a potential formalin substitute for tissue fixation in routine pathological specimens.
OBJECTIVE
To investigate RCL2 as a fixative for tissue fixation in routine histopathological examination and to assess tissue suitability for ancillary investigations.


RESULTS
Forty-nine samples from 36 fresh specimens were cut into three equal pieces and fixed in RCL2 diluted in 100% ethanol, RCL2 in 95% ethanol, or neutral buffered formalin as control. Suitability for microtomy, quality of histomorphology, histochemistry, immunohistochemistry, fluorescent and silver in-situ hybridization analysis and extracted genomic DNA were assessed. Microtomy was straightforward in most tissue blocks, but there was difficulty in cutting in approximately a quarter of samples, which required careful handling by an experienced technician. There were no significant differences in tissue morphology between RCL2- and formalin-fixed tissues (P=0.08). Generally, the quality of histochemical staining, immunohistochemistry and in-situ hybridization were comparable to that of formalin-fixed tissues. Inconsistent immunoreactivity was noted, however, with antibodies against pan-cytokeratin and progesterone receptor. Genomic DNA concentration was higher in RCL2-fixed tissues. Using RCL2 diluted in 95% ethanol did not affect fixation quality.


CONCLUSIONS
RCL2 is a potential formalin substitute suitable as a fixative for use in routine histopathological examination; however, difficulty in microtomy and occasional discrepancies in immunohistochemical reactivity require further optimization of the methodology.
Pathology Department, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia. noraidah@ppukm.ukm.my
Noraidah
N
Masir
Mahdiieh
M
Ghoddoosi
Suhada
S
Mansor
Faridah
F
Abdul-Rahman
Chandramaya S
CS
Florence
Nor Azlin
NA
Mohamed-Ismail
Mohammad-Rafaee
MR
Tamby
Nani Harlina
NH
Md-Latar
D004247:DNA / Q000235:genetics; D005260:Female; D005404:Fixatives; D005557:Formaldehyde; D016678:Genome / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008867:Microtomy; D016622:Silver Staining / Q000379:methods; D016707:Tissue Fixation / Q000379:methods*
D005404:Fixatives; D005557:Formaldehyde; D004247:DNA