Mucin histochemistry of cystitis glandularis and primary adenocarcinoma of the urinary bladder.

We describe the histochemical properties of mucin in three cases of cystitis glandularis affecting the urinary bladder. Of particular importance is the positive staining reaction that was obtained with the periodate borohydride/potassium hydroxide/PAS (PB/KOH/PAS) technique, indicating the presence of O-acetylated sialic acids. This reaction has been regarded as unique to the epithelial mucins in the normal terminal ileum and large intestine. Therefore, cystitis glandularis represents a true mucous metaplasia of large intestinal type. A case of primary adenovillous carcinoma of the bladder associated with cystitis glandularis also produced O-acetylated sialomucin, whereas a primary adenocarcinoma of urachal origin did not. The demonstration of O-acetylated sialic acid producing glandular epithelium in the bladder cannot be assumed to represent a metastasis from a colorectal cancer. The PB/KOH/PAS staining technique may provide a means of distinguishing between primary adenovillous and primary urachal carcinoma of the bladder.