Exploratory Comparison of 10% NBF and Methanol Fixation in Adenomyosis Uterine Tissue

Background: Fixation is critical for routine histology, but alternative alcohol fixatives may produce different staining characteristics from 10% neutral buffered formalin. Objectives: This exploratory laboratory study compared hematoxylin and eosin staining quality in adenomyosis uterine tissue from two hysterectomy donors. Methods: Forty histology slides were evaluated, with 20 slides in the 10% neutral buffered formalin group and 20 in the methanol group. Nuclear, cytoplasmic, and cell boundary staining were scored as adequate or good by light microscopy at 10x and 40x magnification. Results: Good scores were more frequent with formalin than methanol for nuclei (60.0% vs 25.0%), cytoplasm (65.0% vs 20.0%), and cell boundaries (70.0% vs 25.0%). Mann Whitney output showed asymptotic p values of 0.027, 0.004, and 0.005, respectively; the reported exact value for nuclear staining was 0.060 and was not corrected for ties. Conclusions: Because only two biological donors contributed the slides, findings are interpreted descriptively as a pilot comparison. Under the tested laboratory conditions, formalin showed more favorable slide level staining scores, while confirmation in a larger donor series with standardized allocation and masked scoring is required.