ALCIAN BLUE pH;

Abstract

Background: Alcian blue (AB) is a cationic dye that stains mucins especially acidic mucins into varying shades of blue colour depending on the pH of the dye. GIT comprises of three main portions, fore-, mid- and hind-gut, which develops from different embryological areas. Their epithelial lining presents with varying degree of diversity including their secretions. Studies have shown that there is a tendency of cellular modification (physical and chemical) including secretions during tumour morphogenesis. With recent increase in GIT tumours especially epithelial tumours, Alcian Blue staining of mucins produced by these tumours at different pH more than conventional pH might give valuable information on the property of these tumours. Setting: The study was conducted in the Histopathology and Morbid Anatomy unit, department of Laboratory services, Muhimbili National Hospital, Tanzania. Study design: This was a hospital based retrospective study, in which archival data and blocks were retrieved. Objective: To determine the effect of pH and pattern of Alcian blue staining on primary GIT epithelial tumours tumours. Materials and Methods: Information on patients were obtained from cancer registry and patient files. Paraffin blocks were retrieved from archive, sections were cut using rotary microtome at 3μm (SAKURA). Haematoxylin and Eosin (H&E) and AB staining at pH 1, 1.5, 2 and 2.5 was done for each case and control. H&E slides were reviewed for confirmation of the diagnosis primary epithelial tumours and AB stained slides were evaluated for staining reaction and graded. Results: Out of 87 GIT primary epithelial tumours which were evaluated, AB staining was positive in 21 (24.1%) cases, the majority of these (11 (52.4%)) were from hindgut. Positive AB staining of GIT epithelial tumours increased as the tumour became more differentiated irrespective of location. Majority of tumours with positive AB staining was observed at pH 2 in GIT epithelial tumours as opposed to the conventional pH of 1 and 2.5 respectively. Conclusions and recommendation: The majority of primary GIT epithelial tumours stained positively at pH 2 irrespective of the location. However tumour differentiation influenced AB staining whereby well-differentiated tumours were mostly positively stained. It is recommended that AB at pH 2 should be applied when staining GIT epithelial tumours rather than conventional pH of 1 and 2.5. However the degree of differentiation should be considered since poorly differentiated tumours are likely to give negative results with AB staining.