Prolonging fixation time of an alternative fixative to formalin for dermatological samples using standard laboratory protocols

• Autor(a) principal: Smith, Julie
• Data de Publicação: 2020
• Outros Autores: Faria, Cláudia Sofia, Qvist, Camilla Christine, Melchior, Linea C., Lauridsen, Thomas, Antunes, Angélica
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.21/12187
• topic: Diagnostic techniques; Procedures; Immunohistochemistry; Medical laboratory science; Molecular biology; Skin

Aims: Though formalin remains to be the gold standard fixative in pathology departments, analytical challenges persist for nucleic acid evaluations. In our laboratory, formalin fixation of skin samples, in particular, impairs diagnostic accuracy and demands repetition of biopsies and analytical procedures. PAXgene Tissue Systems may be an alternative; however, according to manufacturer specifications, it only allows fixation for 48 hours before having to add a stabilizer. This may be a challenge in laboratories, which are closed on weekends and bank holidays. Our aim was to validate this alternative fixative for dermatological samples with prolonged fixation times using standard laboratory protocols developed for formalin-fixed specimens. We compared the results with gold standard formalin fixation. Methods: Skin specimens were formalin or PAXgene fixed for either 2 hours, 24 hours, 3 days or 7 days, paraffin-embedded, analyzed, and scored by observers. Results: Generally, formalin outperformed PAXgene fixation in H&E stains and fluorescence in situ hybridization (FISH), but both seem usable for diagnostics. The time of PAXgene fixation did not have an impact on alcian blue-Van Gieson (ABVG), H&E (p=0.48), nor immunohistochemistry (p=0.74). There was a tendency towards best PAXgene performance at 24 hours of fixation for FISH and for DNA integrity analysis 24 hours or 3 days. Conclusions: Prolonging PAXgene fixation time to 3 days before adding stabilizer does not seem to have a major impact on the performance of general diagnostic analysis, but our preliminary results show the optimisation of internal protocols is needed. PAXgene is an expensive alternative and may be confined to some dermatological samples.