Comparison between 70% ethyl alcohol and 10% formalin as fixative mediums in surgical cooperation campaigns: a pilot study

Background: The lack of adequate resources in international cooperation limits the study of anatomopathological specimens. The literature on potentially inexpensive and available fixation media is scarce. Material and methods: Our surgical team prospectively collected specimens during cooperation campaigns developed in Senegal. Lesions were fixed in parallel in 10% formalin (FF) and 70% ethyl alcohol (AF). Hematoxylin and eosin sections (HE) and immunohistochemistry (IHC) techniques were performed. Images were anonymized and assessed by two senior and two junior pathologists, who evaluated the quality of staining and diagnostic feasibility using an anonymized questionnaire. Results: Three surgical specimens were included: 1 lymph node (3 HE, 4 IHC), one seborrheic keratosis (2 HE, 5 IHC), and one branchial remnant (2 HE, 2 IHC). Fixation times were similar in all the specimens (10-13 days). All FF HE were diagnostic. AF H&E was 100% diagnostic in the 5/7 sections and 75% in the remaining sections. In most cases, pathologists preferred FF. CK7, P40, EMA, CKAE1/AE3, and TTF1 were 100% diagnostic in both groups. CD20, CD45, and EMA were 100% diagnostic (FF) and 75% diagnostic (AF). CD10 was 75% diagnostic (FF) and 25% diagnostic (AF). BCL6 was 75% diagnostic (FF) and 100% diagnostic (AF). IHC preferences were inconsistent. Conclusions: 70% ethyl alcohol has a worse fixation profile than 10% formalin but allows diagnosis in most cases. The immunoreactivity observed is variable depending on the tissue and the stain used. Based on these findings, it can be considered an inexpensive, readily available, and potentially helpful fixation medium for diagnosis in developing countries where surgical cooperation campaigns are conducted. Nevertheless, future studies of larger sample sizes and characterizing other histologic subtypes are needed to confirm these findings.