Aims The authors previously reported the expression of keratan sulfate (KS), a glycosaminoglycan, in the epithelium of normal and neoplastic endometria. The aim of this study was to evaluate its potential use as a diagnostic marker, and the expression of KS was investigated in other human epithelial tissues.

Methods Expression was examined immunohistochemically using 102 samples of normal epithelia and 110 samples of carcinomas from the female genital tract (FGT; cervix, endometrium, ovary, fallopian tube), digestive organs (gastrointestinal tract, pancreas, liver), urinary tract, lung, mammary gland, thyroid and mesothelium.

Results In normal tissues, KS was consistently detected in the FGT and ectopic endometrium (25/26), but was not found in the digestive organs (1/42) and urinary tract (0/6), and was only partly detected in the lung (7/10), mammary gland (3/9) and thyroid (4/4). In malignant tissues, KS was consistently observed in carcinomas of the endometrium, ovary and fallopian tube (29/32), and was partly detected in carcinomas of the lung, mammary gland, thyroid, pancreas and mesothelium, but was absent in carcinomas of the gastrointestinal tract (0/17), liver (0/5) and urinary tract (0/11). Among carcinomas of the FGT, digestive organs and urinary tract, KS positivity suggested the possibility of FGT carcinomas, with 79.5% (31/39) sensitivity and 92.9% (39/42) specificity.

Conclusions KS is a potentially useful marker for the supportive diagnosis of the primary site of metastatic carcinomas or unknown primary carcinomas, especially in the abdominal cavity.