Renal Pelvic Urothelial Carcinoma with Divergent Morphology
GQ Xiao, J Chow, PD Unger. Mount Sinai School of Medicine, New York, NY
Background: Morphological variation due to aberrant differentiation is a well-recognized phenomenon in urothelial carcinoma (UC). Compared with that of the urinary bladder, UC of the renal pelvis is infrequent and its morphologic features and presentations have only sporadically been described.
Design: Nephroureterectomies performed for primary UC of the pelvicalyces in the past 6 years were retrospectively reviewed. All the tumors were graded, staged, as well as evaluated for their gross and microscopic pathology.
Results: A total of 59 pelvicalyceal UCs were identified, among which were 13 (22%) low-grade and 46 (78%) high-grade tumors. All 13 low-grade pelvicalyceal UCs were noninvasive and none of them displayed divergent differentiation. Of 46 high grade UCs, 18 (39%) contained a variable amount of divergent morphology. The percentage of divergent morphology in the tumor ranged from 10% to 98%. Compared to 21% of classical UCs, 78% of UCs with divergent morphology displayed a tumor stage of pT2 and above, and this difference was statistically significant (p<0.05) (See Table). The morphologic variants included nested, small cell, osteoclast-rich, micropapillary, signet ring cell, sarcomatoid, UC with conventional squamous cell/clear cell features, UC with anaplastic giant tumor cells, and UC with glandular differentiation.
Conclusions: High grade and unusual morphology, as well as advanced tumor stage were the frequent findings in pelvicalyceal urothelial carcinomas. In addition, divergent morphology was correlated with advanced tumor stage for these tumors.
|UC||Conventional High Grade UC||High Grade UC with Divergent Differentiation||Low Grade|
|pT1||12 (43%)||4 (22%)|
|pT2||1 (4%)||3 (17%)|
|pT3||5 (18%)||10 (56%)|
|Regional lymph node metastasis||0||2|
|Distant metastasis at diagnosis||0||1|