Collecting duct carcinoma is a highly aggressive renal epithelial
malignancy, although it accounts for less than 1% of the incidence of renal
epithelial neoplasms. Differential diagnoses between
collecting duct carcinoma, pelvic urothelial
carcinoma with marked invasion to the renal parenchyma (invasive urothelial
carcinoma), and
papillary renal cell carcinoma is often challenging. In our current study, we examined the utility of using commercially available
antibodies, in conjunction with
lectin histochemistry, for such differential diagnoses. We examined 17 cases of
collecting duct carcinoma, 10 cases of invasive urothelial
carcinoma and 15 cases of
papillary renal cell carcinoma (type 1, 6 cases; type 2, 9 cases) in these evaluations. Our results indicated that Ulex europaeus
agglutinin 1,
E-cadherin, and c-KIT were frequently positive in
collecting duct carcinoma and invasive urothelial
carcinoma, in comparison with
papillary renal cell carcinoma, which had negative results for CD10 and
alpha-methylacyl CoA racemase. We found, however, that
collecting duct carcinoma showed positivity for high-molecular-weight
cytokeratin and low-molecular-weight
cytokeratin at a low frequency compared with invasive urothelial
carcinoma, and that these distinctions need further careful evaluation. In addition, high-molecular-weight
cytokeratin positivity was not a reliable marker for
collecting duct carcinoma. We conclude that Ulex europaeus
agglutinin 1 reactivity and positivity for
E-cadherin and c-KIT are effective in distinguishing
collecting duct carcinoma from
papillary renal cell carcinoma, and that negative results for
alpha-methylacyl CoA racemase and CD10 are potentially useful hallmarks of this distinction also. In contrast, a differential diagnosis for
collecting duct carcinoma and invasive urothelial
carcinoma will require careful examination of multiple routinely stained specimens, particularly in cases of in situ neoplastic lesions in the pelvic mucosa.