Value of thrombomodulin immunostaining in the diagnosis of transitional cell carcinoma: a comparative study with carcinoembryonic antigen.

AIMS

Thrombomodulin (TM) is a surface glycoprotein involved in the regulation of intravascular coagulation that has been reported to be expressed in a variety of tumours. We investigated TM expression in transitional cell carcinoma (TCC) and compared the value of TM immunostaining with that of carcinoembryonic antigen (CEA) for differentiating TCC from other tumours with which it may be confused.

METHODS AND RESULTS

Immunostaining was performed on formalin-fixed, paraffin-embedded tissue sections using the avidin-biotin-peroxidase complex method. TM immunoreactivity was observed in 80 of 91 primary (51/58 urinary bladder 10/12 renal pelvis, 3/3 ureter. 15/15 prostate, 1/3 ovary), and 18 of 20 metastatic TCCs expressed this marker. Only 37 of the 91 primary (23/58 urinary bladder, 4/12 renal pelvis, 1/3 ureter, 9/15 prostate, 0/3 ovary) and six of the 20 metastatic TCCs reacted for CEA. In order to evaluate the practical utility of TM immunostaining in surgical pathology, 30 adenocarcinomas of the prostate, 18 of the bladder, 12 of the colon, and 22 renal cell carcinomas were also stained for these markers. CEA reactivity was obtained in 12 of 30 adenocarcinomas of the prostate, 12 of 18 of the bladder, and 12 of 12 of the colon, but in none of the 22 renal cell carcinomas. Only three of the 18 adenocarcinomas of the bladder showed focal TM reactivity, but no staining for this marker was observed in any of the other types of tumours.

CONCLUSIONS

TM is a more sensitive marker than CEA for TCC and, because it has a more restricted reactivity with other tumours. TM has more practical value in separating TCCs from adenocarcinomas of the prostate, colon and bladder, and renal cell carcinomas than CEA.