Acid mucin and high molecular weight cytokeratin in prostatic lesions: evaluation of a combined histochemical and immunohistochemical stain

Objective To evaluate the presence of acid mucins and high molecular weight cytokeratin (KER) in prostatic lesions using a combined histochemical and immunohistochemical stain consisting of Alcian blue at pH 2.5(AB) with a strept‐avidin‐biotin complex (SAB) staining for KER (SAB‐KER). Materials and methods Sections were obtained from archival paraffin blocks which included 20 cases of prostatic carcinoma, 30 cases of benign hyperplasia, and five cases of basal cell hyperplasia. Sections were stained for mucosubstances using the AB stain, for KER using SAB‐KER and by both AB and SAB‐KER, the combined stain (CS). Results With the CS stain KER, which is present in the prostatic basal cells, was not detected in malignant glands and in 60% of these cases intraluminal blue‐stained acidic mucin was seen. On the other hand, all benign hyperplastic prostatic glands were devoid of intraluminal acidic mucin and showed staining for KER of their basal cells. Areas of basal cell hyperplasia were strongly positive for KER and intraluminal acidic mucin was seen in one case. Each of the stains separately gave similar results to the CS method but the contrast between the areas of carcinoma and hyperplasia was accentuated by the CS. and small foci of carcinoma were easily detected. Conclusion The combined AB + SAB‐KER stain is quicker to perform and allows the simultaneous appraisal of acid mucin and KER.